Neuroimmunology in Clinical Practice - part 3 pdf

Multiple sclerosis 49 manual dexterity, impaired verbal memory and language deficits in all forms of the disease. Cortical aphasia, agnosia, and apraxia are rare in MS, while verbal fluency and verbal memory are often impaired relatively early during the disease. Callosal discon- nection as well as alexia without agraphia was described in case reports (Mao-Draayer and Panitch, 2004). Since the observed cognitive abnormalities predominantly affect executive functions, such impairments by themselves may become highly disabling in MS, and significantly interfere with professional and social functioning. The combination of abnormalities in attention, planning, working memory, speed of information processing and visuo-spatial skills, along with physical disability, can significantly interfere with the performance of complex daily tasks. Impairments in all cognitive domains may result from a diffuse distribution of microscopic pathology, while a large lobar lesion can present with a predominant lobar deficit. Extensive cortical pathology accompanying varying loads of subcortical lesions may result in mixed forms of dementia (Buchanan et al., 2005). The severity of cognitive impairment best correlates with the total cerebral disease burden defined by recently developed conventional and nonconventional MRI sequences, and both gray- and white-matter atrophy contributes to cognitive and neuropsychological impairments in MS (Sanfilipo et al., 2006). Metabolic and functional abnormalities detected by PET scan or functional MRI in cortical neurons likely reflect disruption of intercortical and subcortical pathways, lesions directly affecting neurons and toxic effect of soluble inflammatory products (De Souza et al., 2002; La Rocca, 2000; Rao et al., 1991). A trans-synaptic alteration of neuronal activity is also possible. Mapping of compensatory changes and plasticity of the brain represents an important field of functional imaging (Tartaglia and Arnold, 2006). Psychological disability in MS most commonly includes emotional lability, irritability, euphoria, apathy, depression, bipolar disorder, suicidal ideation, anti- social behavior, and psychosis (Figved et al., 2005; De Souza et al., 2002). These symptoms negatively influence the quality of life and add to the disabling effects of cognitive abnormalities. Depression may be caused by the disruption of normal anatomy, changes in neurotransmitter production, and alteration of the neuroendocrine pathways. Reaction to disability and medication side effects may also contribute to depression. Most studies testing the relationship between depression and cognition suggest that there is little or no relationship. However, a meta- analysis by Thronton and Naftail (1997) reveals a strong correlation between depression and working memory, but no relationship between depression and short-term or long-term memory (La Rocca, 2000; De Souza et al., 2002). Euphoria is an inappro- priate expression of optimism and happiness that is often associated with signs of emotional dysin- hibition. Euphoria usually results from a diffuse and severe pathology in patients with advanced physical and cognitive disability. Bedside testing cannot adequately assess cognitive function or mood disorders, and the use of comprehensive neuropsychological batteries may be necessary in a great proportion of MS patients. The increasing availability of immunomodulatory, neuroprotective, antipsychotic, and mood-stabilizer drugs, along with other symptomatic treatments and rehabilitation methods, underscore the importance of early evaluation of cognitive and mood disorders in MS. Variants of MS ON, ATM, Marburg’s type of MS and Balo’s con- centric sclerosis are discussed above. Neuromyelitis optica or Dévic’s disease is reviewed in Chapter 4. MS mimics There are several autoimmune, infectious, and granulomatosus disorders which imitate sporadic MS. A short list includes lupus, Sjögren’s syndrome, Behçet’s disease, antiphospholipid antibody syndromes, Susac’s syndrome, Lyme disease, cysticercosis, and sarcoidosis. The history, clinical presentation, MRI characteristics, and a comprehensive laboratory work up usually help to establish the differential diagnosis. Familial forms of MS occasionally present with pseudomendelian inherit- ance patterns. Therefore, inherited forms of white- matter diseases including leukodystrophies with autosomal dominant, recessive, or X-linked transmission patterns have been misdiagnosed as familial MS. Adrenomyeloneuropathy, an adult-onset vari- ant of X-linked adrenoleukodystrophy, can particularly pose diagnostic difficulties. Alexander’s disease and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) are other rare disorders with features imitating MS. The recently described vanishing white-matter disease only seldom causes confusion NICP_C03 04/05/2007 12:26PM Page 49 50 BERNADETTE KALMAN ET AL. with MS. With the recent availability of imaging, specific molecular genetic and biochemical tests, the diagnostic dilemma can be easily solved in most of these disorders (Kalman and Leist, 2004). Pregnancy and MS While family planning may profoundly be influenced by the level of disability in MS patients, the effect of pregnancy on the disease has also been a matter of controversy. Korn-Lubetzki et al. (1984) determined in a large retrospective study that the frequency of relapses decreased during pregnancy, increased in the postpartum period, and was similar in the pregnancy year (nine months pregnancy plus three months postpartum) to that of out of pregnancy. The Pregnancy in Multiple Sclerosis (PRIMS) study was a large prospective natural history analysis of MS in pregnant women (Confavreux et al., 1998). This multicenter study confirmed the significant decline of relapse rate during pregnancy, most marked in the third trimester, and the increase of relapse rate in the first three months postpartum. However, no acceleration of disability was noted during the puerperium, and neither breast feeding nor epidural analgesia had negative effects. In an extension of this study, patients were followed up to two years postpartum (Vukusic et al., 2004). This second PRIMS study added that from the second trimester onwards and for the following 21 months, the annualized relapse rate did not significantly differ from that of the prepregnancy year. Despite the increased risk in the first three postpartum months, 72% of women did not have relapses. Increased relapse rate in the prepregnancy year and during pregnancy and a higher disability status score at pregnancy onset, correlated with the postpartum relapses. 3.5 The pathology of MS: A quest for clinical correlation (William F. Hickey) Introduction Merely a decade ago if one were to delve into the basic pathology of MS, the picture that would emerge was relatively consistent, but it contained great variability. The pathognomonic lesions of MS, called plaques, were chronic inflammatory foci randomly affecting the white matter of the central nervous system that resulted in myelin loss and gliosis (Figs. 3.5 and 3.6). The features of the histological lesions of MS have long been acknowledged to be highly variable. They differed with the age of the lesion and seemed to correlate poorly with the clinical syndrome exhibited by the patient (Figs. 3.5 and 3.6), except for the fact that if they were situated in the CNS at a specific site, they could be correlated with the resulting neurological deficit. Their histological Old plaque with myelin loss gliosis and axonal loss (late) B CDA Fig. 3.5 The gross photographs (A) of the parietal lobes with totally demyelinated, old MS plaques in the periventricular area on each section. Histological sections were prepared from the brain slice in the lower right, and are depicted in B–D. B is a Holzer stain to demonstrate gliosis that extends well beyond the area of the MS plaque itself. C is a Bodian stain and D is a Bielshowsky stain which identify axons. Both demonstrate the near total axonal loss in the demyelinated zone. Fig. 3.6 The edge of a typical, actively demyelinating MS plaque is shown (hematoxylin and eosin (H&E) stain, X125). The tissue at site “A” is neither inflamed nor demyelinated, and no loss of oligodendroglia has occurred. At site “B” loss of myelin and oligodendroglial cells is nearly complete. As indicated by the arrow, the border of the advancing plaque is hypercellular and contains large numbers of T cells and macrophages. NICP_C03 04/05/2007 12:26PM Page 50 Multiple sclerosis 51 appearance neither helped with prognosis, selection of therapy nor insight into etiology or pathogenesis. While there had been steady progress in dissect- ing the structure of MS plaques using immunohistochemical and ultrastructural techniques, the fundamental links between the microscopic features of the plaque and questions regarding etiology, pathogenesis, and prognosis remained opaque (Hickey, 1999; Lassmann, 2005). The various features of the lesions found in MS were reviewed and analyzed at an international symposium that inspected the complexity of MS plaques varying from their im- munological constituents and types of damage to the temporal changes in lesional pathology and clinical correlations (Lassmann et al., 1998). It was obvious that MS was a highly complex, variable, and enigmatic problem. The histopathology of MS has been examined for nearly a century and a half, but progress in understanding the disease has been slow. Pathologists accept that while there are certain general features of the MS lesion that could be expected based on a lesion’s age, inflammatory activity, and the clinical features of the illness, a reliable and informative classification system had not evolved . . . if such a system was ever to prove to be appropriate and useful. Lucchinetti et al. (1996) for the first time proposed a classification schema that apparently permitted MS cases to be characterized and subdivided based upon specific immunohistochemical features of the lesions. The concept that the pathogenesis of MS might fall into a set number of specific patterns, each representing a distinct immunopathological mech- anism, was revolutionary. Pathological subtypes – reality or illusion? While there have been some minor modifications in the proposed classification, at this time there are basically four types of MS lesions that are presumed to be histologically, immunophenotypically, and pathogenetically distinct (Lucchinetti et al., 2005). Type I lesions are those characterized by extensive infiltration by T cells and macrophages. The plaques have sharp, distinct edges and the disappearance of the various molecular components of myelin seems to occur simultaneously, not in a selective or sequent- ial manner. In this type of inflammatory focus some oligodendroglial cells survive the insult and remyelination (partial or complete) may be possible. Shadow plaques, areas of incomplete remyelination, can be associated with type I lesions. In many ways type I lesions are reminiscent of the pathology found in EAE, a well-established animal model of MS. If so, this MS subtype may represent a true autoimmune attack by T cells against one or more specific myelin components. Type II plaques are in many ways similar to the prior type, but are associated with extensive deposition of antibodies and the presence of activated complement components, including formation of the membrane attack complex from the final elements of the complement cascade. The lesions have sharp edges and the loss of myelin components occurs simultaneously. As before, some oligodendroglial cells are able to survive in the inflammatory foci, thus remyelination can occur and shadow plaques are found. This subtype of MS lesion resembles the pathology of EAE induced by MOG. MOG-induced EAE is distinct in that it requires not only antigen- specific T cells, but also the simultaneous presence of anti-MOG antibodies. Hence, it would seem that in type II lesions the T cells may be permitting leak- age of antibodies into the CNS, but it is the binding of antimyelin antibodies and the activation of the complement cascade that actually leads to myelin destruction. Type III lesions are distinct from the former two. While there are T cells and macrophages present, the lesions are irregular and the borders ill-defined. Moreover, in this subtype there seems to be a prefer- ential loss of myelin-associated glycoprotein (MAG) over the other molecular components of compact myelin; in other words, the molecules making up compact myelin are lost selectively. Oligodendroglial cells undergo destruction in what appears to be an apoptotic fashion, their loss is nearly total and remyelination does not seem possible. This MS type is believed to represent a degeneration of oligoden- drocytes that starts at their most distal processes. Since at the subcellular level MAG is restricted to the portions of the oligodendroglial processes in the periaxonal area, it has been suggested that type III lesions may represent a “dying-back oligodendrogliopathy”. Such an unusual finding may be parallel to certain features found in hypoxic/ischemic lesions of the white matter. This has led to the hypothesis that demyelinating foci in some forms of MS may represent hypoxia-like tissue injury (Aboul-Enein et al., 2005). Indeed, it is possible that some form of small-vessel vasculitis, possibly one mediated by activated T cells, may underlie this class of MS damage (Kornek and Lassmann, 2003; Lassmann et al., 1998). NICP_C03 04/05/2007 12:26PM Page 51 52 BERNADETTE KALMAN ET AL. The type IV lesions in MS are a bit more difficult to discern. Those proposing the classification suggest that this subtype may represent a distinct disorder affecting the oligodendroglial cell itself – a so-called primary oligodendrogliopathy. Histologically, the plaques have sharp edges, are infiltrated by T cells and macrophages, and the loss of the various myelin components appears to occur simultaneously. There is abundant apoptotic death of oligodendroglia in the white matter around the edge of the plaque. Yet, the nature of the problem that leads to oligodendroglial death has not been defined. Moreover, this subtype is rare. There are some problems with this proposed classification system. These problems are not necessarily fatal flaws, nor do they reflect negatively on the proponents who advocate immunophenotypically categorizing MS lesions. Certainly, few would expect that an initial classification system based upon a relatively small number of cases would be comprehensive and never need modification or amendment. It is most likely that there will be further refinements of the classification based on yet to be identified parameters. Nevertheless, given the proposed classification system, the current question is whether it should be utilized and broadly applied. It is at this point that we need more data. It is coming, but at this writing, not yet available. The aforementioned classification system was derived from extensive analysis of biopsies from the brains of patients not previously diagnosed with MS who presented acutely with a progressive neurological disorder. Some argue that this represents a highly skewed group of patients, even if the majority (but not all) actually progressed to develop clinical multiple sclerosis. However, following a further analysis of a broader group of patients, the categorization method appears to be sustained (Pittock et al., 2005). Another potential difficulty with the classification system is that it has yet to be replicated and confirmed by a group not associated with the system’s original proponents. Access to MS tissue, the scarcity of MS brain biopsies, the accurate duplication of the reagents and methods used by the original authors, and unfamiliarity with the parameters of analysis of the tissue employed by the authors of the classification method, are all impediments that must be overcome. One of the major questions concerning the categorization of MS lesions which still remains to be resolved is whether MS lesions are homogeneous and consistent within an individual patient, or if a spectrum of histopathological types coexists simultaneously within one person. There are reports from experienced MS pathologists stating that various forms of inflammatory lesions do coexist within individual MS patients (Prineas et al., 2001). Also, studies of some cases of classic relapsing-remitting MS have shown lesions that do not neatly fit into the above categories (Barnett and Prineas, 2004). Others have reported that there is “notable homogeneity within individual patients” (Morales et al., 2006). The answer is elusive, but should appear in the next few years. At present the topic remains a point of much debate. Another final issue with this categorization method centers on the extent to which the various histological types of lesions correlate with specific clinical types of MS. It is generally recognized that the clinical course of MS typically falls into a relapsing- remitting pattern, or the secondary progressive type; the primary-progressive form and the so-called “benign” type are rarer (Lublin, 2005). To date the correlation of histopathological type with clinical subtype is weak at best (Pittock et al., 2005); however, there are ongoing studies that are specifically designed to address this issue of clinical correlation. Can prognosis and therapies be directed by the pathological type? Here there is cause for cautious optimism. A retrospective study by Keegan et al. (2005) predicted that patients with type II lesions – those characterized by extensive antibody and complement deposition – might benefit from therapeutic plasma exchange. This is what they found. Plasma exchange did not seem to benefit those with lesion types I or III, but individuals with type II lesions experienced moderate to substantial neurological improvement. Needless to say, if some correspond- ence between a specific immunohistological pattern and a predictable clinical syndrome emerges, then the classification of MS based on the lesions’ histopathological features will be both broadly accepted and rapidly applied. Axonal pathology – an unexpected, unifying feature From the earliest days of the microscopic study of MS lesions, it has been known that axons are damaged in such lesions. But the paper by Trapp et al. (1998) still caught those who studied MS unawares. What was so amazing was not that axonal damage existed; rather it was the extent to which it was present in MS lesions. Vast numbers of axons were transected NICP_C03 04/05/2007 12:26PM Page 52 Multiple sclerosis 53 in active MS plaques. Even in inactive or marginally active plaques, the axon damage continued. Yet, the most startling observation was that significant axonal damage was occurring in the normal appearing white matter, far away from a site of definable inflammation or demyelination (Bjartmar et al., 2001). While all who study MS agree that axonal damage does occur, the puzzle as to whether axonal damage represents a primary insult versus a secondary phenomenon is unresolved. The work of Trapp and colleagues strongly suggests that the axonal pathology is a unique and primary feature of MS (1998). Axonopathy may be an early feature in MS lesions (Kornek and Lassmann, 2003). Yet some reports have questioned this and proposed that axonal damage occurs in the setting of chronic inflammation and longstanding disease afflicting the CNS, but is not a necessary or acute phenomenon (Kutzelnigg et al., 2005). The potential causes of axonal degeneration are manifold. Obviously, the presence of a chronic inflammatory infiltrate, activated macrophages and reactive microglial cells, and the elaboration of a spectrum of cytokines and reactive oxygen meta- bolites would create an environment conducive to cell membrane damage (Bjartmar et al., 2000). The specific offending entities, however, have not yet been specified. Alternatively, it has recently been proposed that mitochondrial dysfunction may be the cause of the axonal damage (Dutta et al., 2006). Much effort is being expended to dissect this poten- tially critical aspect of MS lesions. The great attention currently being paid to this seemingly isolated feature of the pathology of MS derives from the fact that many if not all of the fixed neurological deficits found in longstanding cases of MS may result from axonal loss rather than demyelination (Trapp et al., 1999). In cases of secondary-progressive MS the constant deteriora- tion of neurological function likewise may be attributable to axonal pathology rather than myelin loss. In addition, the relentlessly progressive axonal loss that seems to occur in MS almost certainly provides the pathological substrate for the extensive atrophy afflicting all MS patients as they age. Cortical lesions in MS The existence of focal lesions in the cerebral cortex of MS patients was a relatively new observation (Bo et al., 2003a). These damaged areas do exhibit gliosis, but are relatively difficult to identify due to the relative absence of dense myelin in the cortex. Indeed, subpial demyelination can be an extensive, but subtle, feature in some cases of MS (Bo et al., 2003b). While loss of myelin occurs in cortical lesions, there is remarkably little inflammatory infiltrate (Bo et al., 2003a). As such, this would suggest that white matter and cortex operate under different rules when it comes to inflammatory demyelination. Perhaps more importantly, this offers the possibility that lymphocytes might not be essential in produc- ing damage leading to demyelination, gliosis, and axonal loss. Even less certain about these cortical and subpial lesions is what they mean clinically. Occasional MS patients exhibit seizures. Are such lesions the cause? Do they contribute to the unusual affect seen in some cases of MS? Can they cause motor or sensory abnormalities? Again, pathological analysis of the CNS has identified a group of lesions that sporadic- ally do develop in MS, but the clinical phenomena attributable to such foci are unknown. Summary In the past decade a system for categorizing the lesions of pathological MS into four discrete subtypes has been proposed. While it is very attractive, some question its validity. Currently it is not in universal use because of the uncertainty regarding its ability to provide any meaningful correlations with etiology, clinical course, prognosis, or therapeutic options. At a deeper level, if the existence of distinct pathological patterns of MS plaques is verified and can be employed by pathologists, do these patterns bespeak different etiologies, different mechanisms, and different clinical syndromes? Likewise the conundrum of whether the CNS lesions are consistently of the same type within a given patient throughout the course of the disease must be resolved. The most elemental and important question regarding MS that will be answered in the next few years has been brought into focus by recent and ongoing pathological analysis of MS tissue. Is MS one disease with widely varying clinical manifestations, or is it actually a number of distinct neuroinflammatory diseases each with its own etiology, pathogenetic mechan- ism, and prognosis? It is very possible that the protean disorder called multiple sclerosis represents a final common pathway for distinct disease entities. With questions such as this to be resolved the excitement surrounding the ongoing immunopathological analysis of MS is not likely to abate soon. NICP_C03 04/05/2007 12:26PM Page 53 54 BERNADETTE KALMAN ET AL. 3.6 Cerebrospinal fluid (Mark S. Freedman) The cerebrospinal fluid (CSF) or the brain’s “soup”, unlike the blood, is in direct contact with brain cells, hence sampling its contents can give an indication of what processes may be transpiring in the CNS. In the case of inflammatory conditions such as MS, there are abnormalities that reflect activity arising from within the CNS and help to distinguish them from those due to inflammation penetrating the CNS from without. An understanding of just what the CSF can tell you about inflammatory conditions that affect the CNS demands some basic knowledge about CSF as well as the limitations of the tests used to examine it. First it should be pointed out that the blood–brain barrier (BBB) separating the brain from the vascula- ture is not the same as the blood–CSF barrier (BCB) that comes between the CSF and the blood. The BBB tends to be “sealed” by the specialized endothelial tight junctions seen in the CNS, whereas the BCB is fenestrated acting as a specialized macrofilter. Anything that originates in the blood must cross either barrier by means of diffusion that is facil- itated either by specialized transporters (e.g. pro- teins) or by active transport (e.g. glucose). Diffusion across the BBB is dependent on lipid solubility whereas more hydrophilic molecules have an easier passage through the BCB. By measuring the amount of molecules that are formed outside the CNS, but found in CSF, it is possible to get some idea of the “leakiness” of these barriers. Albumin is the simplest molecule measured; formed in the liver, any amount found in the CSF had to have traversed the BCB. It has long been known that the ratio of CSF/serum albumin is a direct measurement of BCB permeability (Q alb ) which increases with age. Using a simple scale, it is possible to estimate whether permeability is in excess of that expected for a given age (see Table 3.5). Conditions that are typically associated with mild to moderate increase in Q alb include neuropathic processes (e.g. Guillain–Barré), neuroborelliosis or meningitis. Typically these inflammatory processes are thought to reduce CSF absorption and therefore reduce the natural flow of CSF, which leads to con- centration of albumin within the CSF. This reduced CSF flow rate would also lead to intra-CSF accumulation of other molecules such as immunoglobulin (Ig). This is the main reason that any measurement of intrathecal Igs must take into account some measure of BCB leakiness to know if the CSF Ig is simply due to diffusion in from the blood, or is the direct result of synthesis within the CNS. Numerous math- ematical formulas have been devised to account for this leakiness, and one of the simplest to use is known as the “Link index” (Link and Tibbling, 1977): Link IgG Index =× 100% (normal range < 70%) Determining that Ig synthesis had to have arisen within the CNS is tantamount to saying that there is an immune process that is taking place locally. Although this is expected in conditions such as MS, it is not specific for that disease; rather localized Ig synthesis is common to any inflammatory CNS condition that leads to humoral immune responses. IgG is the commonest Ig to be evaluated, but similar formulas have been used to assess IgA or IgM, the latter two being of more importance with respect to infectious causes. For instance, in Lyme disease (often considered an important mimic of MS) IgM prevails over IgA or IgG. Usually the Q alb is also markedly elevated beyond that expected for age (see Table 3.5) in the case of CNS infectious conditions, whereas in MS, it is typically normal. Though rarely a concern, as dysfunction of the BCB (indicated by an increase in Q alb ) increases, especially due to conditions outside the CNS such as meningitis, formulas such as the Link index, which are based on a linear relationship become inaccurate, as the relationship becomes hyperbolic in function and more complicated nonlinear formulas are required for accurately assessing localized Ig synthesis (Reiber and Peter, 2001). The commonest cause for a localized increase in Ig is infection. However, nonspecific increases in localized Ig to ubiquitous agents such as measles, rubella or varicella are common in the presence of CNS autoimmune-type conditions and IgG [CSF] /Albumin [CSF] IgG [serum] /Albumin [serum] Table 3.5 Increasing values of Q alb with age. Age (range) Q alb × 10 −3 <15 5 15–29 6 30–39 7 40–59 8 >60 9 NICP_C03 04/05/2007 12:26PM Page 54 Multiple sclerosis 55 this so-called “MRZ reaction” (measles-rubella-zoster) typifies the polyspecific nature of Ig activation that takes place in conditions such as MS (Reiber and Peter, 2001). Qualitative analysis of CSF Ig is key to the diagnosis of conditions such as MS. It is equally important to insure that this assessment be performed in a qualified laboratory in a standardized manner (Freedman et al., 2005). There is a clear consensus as to what constitutes this analysis (Keir and Thompson, 1990) which is to perform isoelectric focusing (IEF) of Ig on agarose gels followed by immunoblotting. This technique separates the Ig present into either distinct “bands” suggesting either a specific infection or autoimmune process or into a smear of protein consistent with a nonspecific increase in Ig. It is imperative that comparison be made of CSF Ig directly with serum Ig, as the presence of bands in CSF that are clearly not in serum is what constitutes the specificity of the intrathecal response. CSF should be applied to gels undiluted, whereas serum is usually diluted empirically 1:400, so as to equate the overall amount of Ig and minimize overloading in the serum lanes which can obscure at times the visibility of “bands”. Five patterns of “banding” will emerge using this methodology (see Fig. 3.7) with types II or III being indicative of intrathecal synthesis of oligcoclonal banding. In most cases, the sensitivity of IEF for detecting oligoclonal bands in MS is >95% (Paolino et al., 1996). It should raise an alarm therefore, if clinical suspicion is high that a patient has MS, but intrathecal synthesis of oligoclonal bands is unde- tected. This means that more times than not, rather than the test being “falsely negative,” the absence of oligoclonal bands usually suggests a diagnosis other than MS (Zeman et al., 1993). In considering what the CSF can tell you, it is important to consider all aspects of CSF analysis: the cells present (differential or cytology), biochem- istry (albumin, glucose, or lactate), as well as the Ig. These features altogether are used to help distinguish between causes of systemic inflammation which spill over into the CNS, such as vasculitis or chronic infection and intrathecal processes such as the autoimmune condition MS. It is also therefore important to draw simultaneously blood for serum analysis alongside the CSF, as well as to send it for biochemical studies, such as glucose. Typically 1–4 partially filled tubes of CSF are required and 1–2 tubes of blood for full analysis. The first tube can sometimes be contaminated with a few red cells from nicking epidural small vessels during the lumbar puncture. The cell count should be performed no later than two hours after obtaining the CSF, otherwise changes in cell shape may hamper the ability to offer a correct and full differential. A red blood cell count that is too high (5–7 × 10 9 /l) probably indicates too much of a traumatic tap, rendering other quantitative measurements more difficult to interpret. If a high number of red cells are noted in the first tube, then the last CSF tube should also be checked for red cells and if the number remains as high as the first tube, then often this is reflective of continued bleeding within the subarachnoid space such as what might be expected in a ruptured cerebral aneurysm of arterio–venous malformation. One only needs 1–2 ml of CSF for cell counts. White blood cell counts in the CSF are typically low (normal <5 × 10 6 /l), with any cells present being of lymphocyte origin. A single neutrophil seen in a sample free of red cells is cause for concern, possibly indicating either an infection or severe CNS injury with necrosis. Higher than normal white blood cell counts have been found in some 34% of MS CSF S 6.5 pH 9.0 CSF S CSF S CSF S CSF S Type 1 Type 2 Type 3 Type 4 Type 5 Fig. 3.7 Isoelectric focusing on agarose gels followed by immunoblotting for IgG. Five classic patterns are known: type 1, no bands in cerebrospinal fluid (CSF) and serum (S) sample; type 2, oligoclonal IgG bands in CSF, not in the S sample, indicative of intrathecal IgG synthesis; type 3, oligoclonal bands in CSF (like type 2) and additional identical oligoclonal bands in CSF and the S sample (like type 4), still indicative of intrathecal IgG synthesis; type 4, identical oligoclonal bands in CSF and the S sample illustrative of a systemic not intrathecal immune reaction, with a leaky or normal or abnormal blood–CSF barrier and oligoclonal bands passively transferred in the CSF; and type 5, monoclonal bands in CSF and the S sample; this is the pattern seen owing to the presence of a paraprotein (monoclonal IgG component). Courtesy of H. Reiber. NICP_C03 04/05/2007 12:26PM Page 55 56 BERNADETTE KALMAN ET AL. cases (Tourtellotte, 1970), however, very high counts (>50 × 10 6 /l) are most unusual in MS. In some cases, the presence of unusual looking cells should prompt a full review of cytopathology to exclude the possibility of neoplasia or to look for inclusions that might occur in certain types of chronic infections such as toxoplasmosis. In some cases where a high white count is due to lymphocytes, a full tube of 7–10 ml CSF should be drawn and sent for a cytospin and stain- ing with cell markers in order to know for instance if the lymphocytes are all B cells, strongly suggesting a diagnosis of lymphoma, or T cells, more reflective of either infection or chronic inflammation. For biochemical studies such as glucose, lactate, or angiotensin-converting enzyme (ACE) 3–4 ml of CSF will usually suffice. Low CSF glucose (when compared to serum, CSF/serum ratio <0.4) and very high total protein content (e.g. >1 g/l) is more consistent with an infectious or neoplastic process. Lactate, where available, is a good substitute and has an advantage over paired CSF–plasma glucose measurements in that only a single CSF measurement is required (Nelson et al., 1986). If infectious causes are considered, then a separate sterile tube for Gram stain and microbial or fungal cultures is required. Special requests should be made in cases of chronic meningitis to look for “acid-fast bacillus” and special cultures requested if tuberculosis is suspected. In all cases, if a specific pathogen is suspected, most times specific antigen testing is available. Regardless, a tube of 3–4 ml of CSF is all that is required for all these analyses. Overall, CSF can be very informative in most cases of suspected CNS disease. A normal CSF in suspected cases of MS or other possible CNS autoimmune entities is often reassuring and indicates that these dia- gnoses are less likely. A typical CSF picture of specific oligoclonal bands in a patient suspected of MS but who has a MRI that is either normal or shows nonspecific lesions and in whom infection has been ruled out would almost certainly turn out to have MS. On the other hand, the finding of a very high protein, a leaky BCB, or a high cell count in someone who clinically is highly suspected of having MS should raise concern that a different diagnosis is being missed. A lumbar puncture to obtain CSF along with some serum is a minor procedure with high yields in terms of reassurance of not missing more treatable conditions such as infections, and can help to reinforce clinical certainty of a diagnosis of MS, when clinical presentation is somewhat vague or MRI results are nonspecific. 3.7 Magnetic resonance imaging characteristics of MS (Jennifer L. Cox and Robert Zivadinov) Introduction MS is an inflammatory disease of the CNS characterized by demyelinating lesions and axonal loss. The immunopathogenic mechanisms underlying disease initiation and disease course are unknown. Current diagnostic criteria (McDonald et al., 2001; Polman et al., 2005) suggest MRI is the most sensitive and specific of the radiological and laboratory tools used to aid in the diagnosis of MS. Although MS could be diagnosed without MRI by waiting for clinical evidence of a second attack, it is strongly recommended that MRI be used when available to demonstrate dis- semination of lesions in space and time. In addition to its diagnostic usefulness, MRI is routinely used to monitor the course of MS disease over time. Although conventional MRI scans such as T2- weighted images (WI) and gadolinium (Gd)-enhanced T1-weighted scans have long been used for clinical diagnosis and monitoring of MS, they cannot distinguish between inflammation, edema, demyelination, Wallerian degeneration, and axonal loss. In addition, they do not exhibit a reliable correlation with clinical measures of disability. Some patients have multiple hyperintense lesions on T2-weighted images, yet show few clinical symptoms of MS, while other patients with few hyperintense lesions may have a marked clinical presentation. The lack of a strong correlation between the presence of lesions observed with conventional MRI and clinical symptoms is often referred to as the “clinical–MRI paradox” (Barkhof, 2002; Zivadinov and Leist, 2005). Further- more, there is increasing evidence that pathological changes in MS can be found in both cortical and subcortical gray-matter structures, yet conventional MRI scans are not able to detect these gray-matter changes. In recent years, the use of nonconventional MRI sequences as well as advanced analysis methods of conventional sequences have allowed the capture of a more global picture of the range of tissue altera- tions caused by inflammation and neurodegeneration. Newer, nonconventional metrics of MRI analysis include measurement of hypointense lesions on T1-weighted imaging (T1-WI), central nervous system atrophy, magnetization transfer imaging (MTI), magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), high-field MRI, and functional MRI (fMRI). NICP_C03 04/05/2007 12:26PM Page 56 Multiple sclerosis 57 When compared to conventional imaging, nonconventional MRI techniques appear to be better surrogate markers for monitoring the destructive pathological processes related to disease activity and clinical progression. The nonconventional techniques can reveal the underlying substrate of intrinsic pathology within lesions and normal appearing brain tissue (NABT) that include edema, inflammation, demyelination, axonal loss, and neurodegeneration (Bakshi et al., 2005; Zivadinov and Bakshi, 2004c). Due to their ability to detect the neurodegenerative aspects of MS, including recent evidence for cortical demyelination (Geurts et al., 2005), these techniques are receiving increased attention as clinically relevant markers of disease progression. This section will dis- cuss both conventional and nonconventional MRI techniques and their role in detecting inflammation and neurodegeneration in MS lesions and NABT. Role of conventional MRI in MS T2-weighted imaging is highly sensitive in detection of hyperintense lesions in the white matter (WM) and, less commonly, the gray matter (GM). The most typical sites for lesions are in the WM: periventricular region, corpus callosum, posterior fossa, and cortical regions (Fig. 3.8). Several MRI sequences are capable of identifying T2 hyperintense lesions; those preferred most often are conventional spin echo, fast spin echo, and fluid-attenuated inversion recovery (FLAIR) (Zivadinov and Bakshi, 2004c). FLAIR provides improved detection over T2-weighted imaging in the evaluation of periventricular and cortical/ juxtacortical lesions, as CSF may mask the visualiza- tion of these plaques on T2-WI (Bakshi et al., 2005; Zivadinov and Bakshi, 2004c). Continuous technical improvements in MRI hardware and software over the last decade have led to the development of more efficient and sensitive pulse sequences. Among them, turbo or fast spin-echo (TSE or FSE) and fast-FLAIR have already demonstrated their usefulness in a wide variety of neurological diseases, including MS (Simon et al., 2006; Zivadinov and Bakshi, 2004c). FSE has shown greater sensitivity than conventional spin-echo in detecting areas of T2 prolongation in MS. On the other hand, fast-FLAIR sequences have emerged as especially helpful in evaluating periventricular and cortical/juxtacortical lesions where CSF signal may mask these plaques on T2-WI (Zivadinov and Bakshi, 2004c). Moreover, double-inversion recovery (DIR) imaging has recently shown a further increase over FLAIR in the ability to detect cortical lesions as well as provide better contrast between GM and WM (Geurts et al., 2005). Due to fat suppression, areas of T2 prolongation can also be detected using short tau inversion recovery (STIR) sequences and, in certain scanning platforms, this sequence may be superior to T2-WI in detecting spinal cord lesions in MS (Campi et al., 2000). An added advantage to using STIR when imaging the optic nerves is increased contrast between lesions and the surrounding retrobulbar fat (Moseley et al., 1998). Recently the Consortium of Multiple Sclerosis Centers (CMSC) proposed MRI consensus guidelines for imaging of the brain and spinal cord in patients with MS (Simon et al., 2006). Recommended for imaging of the brain were sagittal and axial fast spin-echo fluid-attenuated inversion recovery (fast- FLAIR), axial FSE with proton density (PD) and T2- weighting, and post-Gd-enhanced T1 sequences. An axial T1-weighted pre-Gd scan and T1-weighted 3D volume scan were suggested as optional series to include. Recommended for imaging of the spinal cord were sagittal and axial FSE PD-T2 and Gd-enhanced T1 sequences, with a 3D volume scan as optional. ab cd Fig. 3.8 Axial T2-weighted FLAIR image from a 26-year-old female with relapsing-remitting MS showing periventricular (a) cortical, (b) pericallosal (Dawson’s fingers), (c) hyperintense white-matter lesions. (d) Axial T2-weighted FLAIR image from a 25-year-old male with secondary-progressive MS showing hyperintense white matter lesions in the cerebellum and pons. NICP_C03 04/05/2007 12:26PM Page 57 58 BERNADETTE KALMAN ET AL. Similar guidelines have also been provided in Europe by the European Federation of Neurological Science Task Force (Filippi et al., 2006). Despite the sensitivity of T2-WI to reveal disease activity and lesions over time (Paty and Li, 1993), there is only modest correlation between MRI findings and clinical evolution, except in subjects with very early disease (Rudick et al., 2006a; Sailer et al., 1999; Zivadinov et al., 2001b). Several long-term studies have examined the correlation of disability progression and the accumulation of T2-lesion burden. One of the longest MRI studies followed patients with clinically isolated syndrome for up to 14 years (Brex et al., 2002). After five years of follow up, data showed that T2-lesion volume accumulation predicted 25% of the correlation variance in disability, but at 10 years it was down to 16%, and at 14 years, it explained only about 10–12% of the variance. Evidence is increasing that diffuse, and particularly central, brain atrophy as a characteristic of mid-to- late stage MS may influence this relationship. It is possible that T2-lesion volume may be “artificially” lowered by the loss of lesions along with normal appearing tissue. A decrease in the relationship between T2-lesion volume and disability in advanced disease stages cautions against the assumptions that T2-lesion volume progression is a function of disease duration alone and that stabilizing T2-lesion volume indicates a reduction in disease activity (Dwyer et al., 2005; Li et al., 2006). Despite the previously mentioned limits, several strategies for increasing the sensitivity of T2-WI have become available in the last few years. Recent consensus guidelines recommend a ≤3 mm slice thickness on 2D and ≥1.5 mm on 3D acquisition sequences for the evaluation of disease burden in MS patients scanned in clinical routine practice (Simon et al., 2006). Thinner slices provide increased lesion detection and higher measurement consistency. Recent consensus guidelines also recommend that any scanner used in clinical routine practice should operate at a field strength higher than 1.0T. With the introduction of 3T MRI systems into clinical practice, several questions arise, including the comparison of 3T versus 1.5T. It has been previously demonstrated that scanner field strength has a substantial impact on the measured T2 lesion volume (LV), being about 25–40% higher with standard 3T magnets than for lower field scanners (Erskine et al., 2005; Keiper et al., 1998; Sicotte et al., 2003). Higher-field MRI increases specificity in the correlation between detected lesions and clinical disability. Gadolinium enhancement Gd-enhancement in MS lesions has been connected with histopathological findings of the blood–brain barrier breakdown and active inflammation (Filippi, 2000). Gd-enhancing lesions on T1-WI usually correspond to areas of high signal intensity on T2-WI and low signal intensity on unenhanced T1-WI, probably due to edema and demyelination associated with these lesions (Fig. 3.9) (Zivadinov and Bakshi, 2004c). A transient phenomenon in MS, Gd-enhancement is usually detectable for an average of 3–6 weeks, and typically precedes or accompanies the appearance of a majority of new lesions found on T2-WI in MS patients. Most of the enhancing plaques are not associated with the presentation of clinical symptoms and do not correlate with clinical status in cross- sectional, and especially longitudinal, studies in the mid and long term (Kappos et al., 1999; Zivadinov and Leist, 2005). This discrepancy supports the concept that varied factors operate in the occurrence of relapses in MS as well as the development of long- term sustained disability. Nevertheless, the presence of continuing enhancement indicates a higher risk of relapses over the short-to-intermediate term and may contribute to long-term clinical dysfunction (Filippi, 2000; Zivadinov and Bakshi, 2004c). Several strategies have been proposed to increase the sensitivity of Gd-enhanced MRI for the detection of active MS lesions. One analysis strategy examines the pattern of Gd-enhanced lesions and their relationship to lesions found on other MRI sequences. Deter- mination of an enhancement pattern may indicate differences in the histopathology of MS plaques. Con- centric ring-enhancing lesions with central contrast pallor arise in previously damaged areas or in areas of accelerated local inflammation (Zivadinov and Leist, 2005). When compared with homogeneously enhancing plaques, ring-enhancing lesions are larger, have a shorter duration of enhancement, lower apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR) (Minneboo et al., 2005; Morgen et al., 2001). It has also been shown that ring-enhancing lesions are strong predictors for the development of persisting hypointense lesions on T1-W1 and brain atrophy (Bagnato et al., 2003; Minneboo et al., 2005; Zivadinov et al., 2004). Thus, the appearance of ring-enhancing plaques on Gd-enhanced MRI may not only be characteristic of a more aggressive form of MS but also predictive of long-term deteri- oration. Other strategies that maximize the amount of information that can be obtained through Gd NICP_C03 04/05/2007 12:26PM Page 58 [...]... anti-CD6; anti-CD3 (OKT3); anti-Vβ5.2/5 .3+ T cells; anti-CD4; integrin inhibitors Inhibitors of intracellular Lymphocyte-specific cytoplasmic protein – tyrosine kinase P56lck; zeta-associated activation, signaling and protein (ZAP )-7 0; protein kinase C theta; mitogen-activated protein kinase; nuclear factor of activated T cells; inhibitors of calcium release – activated Ca channels; T-cell proliferation... immune-system effects of natalizumab may increase the risk for infection Pneumonia, urinary tract infections, gastroenteritis, vaginal infections, dental infections, tonsillitis, and herpes infections occurred more frequently in natalizumab-treated patients than in placebo-treated patients in clinical trials In the monotherapy natalizumab study, the incidence of serious infection was 2.1% in natalizumab-treated... vitamin E); neurotrophic factors; transplantation of stem cells; rHIgM22 (remyelinating monoclonal antibodies); IN- 1 (anti-Nogo-A mAb) Pyrimadine synthesis inhibitor (teriflunamide); CCI-779 (ester or sirolimus); FTY720 New oral (inhibits T-cell circulation); xaliproden (inhibits cytokine synthesis); statins (induce immunosuppressant/ T-helper-cell cytokine shift and reduce T-cell migration); chemokine... in relapsing-remitting MS, is a synthetic peptide composed of L-alanine, L-glutamic acid, L-lycine, and L-tyrosine and was designed to mimic the structure of myelin basic protein GA is administered subcutaneously daily at a dose of 20 mg and has been shown, in large randomized control trials, to reduce the rate of clinical relapse and of development of gadolinium-enhancing MRI lesions and T1-weighted... NICP_C 03 04/05/2007 12:26PM Page 71 71 Multiple sclerosis Table 3. 6 Evolving/Investigational treatments for MS (Noseworthy et al., 2005, Kappos et al., 2004) Category Agents CTLA4-Ig (structural homolog of CD28); daclizumab (targets α subunit of the high-affinity interleukin-2 receptor, anti-CD25); alemtuzumab (anti-CD52, Campath 1H); rituximab (anti-CD20); anti-CD40L/-CD154 (IDEC- 131 ); anti-IL-12, anti-CD6;...NICP_C 03 04/05/2007 12:26PM Page 59 59 Multiple sclerosis a b c d e f Fig 3. 9 Comparison of images from a 25-year-old male with secondary-progressive MS (a, b, c) showing homogeneously enhancing lesions (a) and from a 29-year-old female with relapsing-remitting MS (d, e, f ) showing ring-enhancing lesions (d) (a) and (d): Single dose (0.1 mmol/kg) gadolinium postcontrast axial T1-weighted images... anti-alpha 4 integrin monoclonal antibody recently licensed for use in relapsing-remitting MS, did not reveal any benefit over placebo in terms of clinical improvement when given within 2–4 days of acute relapse (O’Connor et al., 2004) Randomized studies investigating the use of intravenous immunoglobulin (IVIg) administered with or before intravenous methylprednisolone in patients with acute relapses in. .. IFNβ in secondary-progressive MS is vague A study from the United Kingdom reported slowing of disease progression with Betaseron (European Study Group on interferon-beta-1b in secondary-progressive MS, 1998) A subsequent North American trial did not confirm this finding (Secondary Progressive Efficacy Clinical Trial of Recombinant Interferon-beta-1a in MS (SPECTRIMS) Study Group, 2001) Improvements in some... proliferation Janus protein tyrosine kinase (JAK 3) inhibitors; inhibitors of pyrimidine biosynthesis (gemcitabine, leflunomide, and FK778); inosine monophosphage dehydrogenase inhibitor; VX-497; vaccination with T cells or T-cell receptor peptides AMPA/kainite receptor antagonists (talampanel, E2007); riluzole (inhibitor of Neuroprotective and glutamate transmission); Na channel blockers; inhibitors of Na/Ca... high-field MRI are emerging as promising tools for improving our understanding of the pathophysiology of MS By considering information from multiple neuroimaging methods and analyses, we will gain a better understanding of the relationship between MRI findings and clinical symptoms and disease course The clinical MRI paradox” will not remain such a mystery as we look beyond conventional MRI measures 3. 8 . used in clinical routine practice should operate at a field strength higher than 1.0T. With the introduction of 3T MRI systems into clinical practice, several questions arise, including the comparison. relapsing-remitting MS, is a synthetic peptide composed of L-alanine, L-glutamic acid, L-lycine, and L-tyrosine and was designed to mimic the structure of myelin basic protein. GA is administered. include actions that (i) inhibit T-cell costimulation and/or activation processes; (ii) modulate anti -in ammatory and proinflammatory cytokines; (iii) inhibit interferon gamma-induced class-II

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