Neurological Differential Diagnosis - part 4 pdf

154 Chapter 4 persons whom actually witnessed the event. Family history can also yield critical information. Careful exam should focus on any focal neurologic signs. 2 Electroencephalogram. Initially, a routine sleep/wake EEG should be ordered. It is common to observe a ‘normal’ recording over 30 minutes even in patients with known seizure disorders. Therefore, a routine interictal EEG may not demonstrate epileptiform activity and should not be interpreted as defi nitive in ruling out sei- zures. Sensitivity can be increased by: repeat exams, records obtained within 24 hours of an ictal event, or prolonged monitoring such as continuous telemetry. 3 Neuroimaging. MRI is the modality of choice and should include gadolinium contrast to assess infectious or neoplastic processes. A CT scan with and without contrast is acceptable only when MRI is not available or contraindicated. Risk factors for recurrent seizures 1 EEG demonstrating epileptiform discharges 2 Abnormal neurological exam fi ndings 3 History of neurological defi cit from birth such as mental retardation or cerebral palsy 4 Age less than 16 years old 5 Seizure occurring during sleep 6 Status epilepticus or multiple seizures within 24 hours as the initial presentation 7 Partial seizures 8 Todd paralysis Differential diagnosis of recurrent seizures • The decision to initiate anti-epileptic medication following a single seizure should take into account the likelihood of recurrence. • Lifetime incidence of a single seizure in the general population is approximately 10%. This does not necessarily imply epilepsy requiring lifelong treatment. • Good candidates for discontinuation of previously initiated anti-epileptic medical treatment include: seizures easily controlled with monotherapy, prior two-year seizure-free period, idiopathic seizure, normal EEG (2×), seizure onset in childhood, and normal neurological exam. • The following list are features that should be considered risk factors for recurrent seizure. • Seizure recurrence should be divided into patients with a previous diagnosis who are currently treated and those individuals with a single previous seizure who are currently not treated. Paroxysmal Disorders 155 The following should be considered in evaluating recurrent seizures: 1 Inadequate serum drug levels and patient compliance ◆ Check serum levels and also check for appropriate dose. 2 Addition of other medications which may adversely infl uence anti-epileptic drug metabolism 3 Ongoing infection ◆ In patients with prior neurosurgical intervention, CNS infection must be ruled out. ◆ Otherwise, CNS infection is fairly rare. ◆ Epileptic patients with systemic infection/fever, may be more prone to break- through seizures at times of illness. 4 Metabolic and/or electrolyte disturbances ◆ Hyponatremia, especially in patients on carbamazepine. ◆ Hypocalcemia. ◆ Hypoglycemia, especially in diabetics. 5 Progression of previously documented disease, especially neoplastic processes 6 Alcohol or drug ingestion or withdrawal 7 Heightened stress or anxiety 8 Sleep deprivation Differential diagnosis of staring spells 1 Daydreaming ◆ May be overcome by loud or startling noises. ◆ No post-event confusion or lethargy. ◆ Not associated with automatisms. 2 Inattention ◆ As above. • In patients with a single previous seizure, strong consideration should be given to initiating treatment, taking into account presumed etiology and risks for recurrent seizure (see recurrent risk document) • Multiple physiologic, metabolic, and psychosocial factors may reduce seizure threshold in previously well-controlled patients • Characterized by fi xed gaze of variable duration. • Most commonly seen in the pediatric population. • Usually benign in nature, though important to rule out seizure activity with careful history-taking and appropriate diagnostic testing. 156 Chapter 4 3 Hearing loss ◆ Concerning if staring cannot be interrupted by a variety of different sound sources. ◆ Associated with developmental delay, especially concerning language. ◆ Should be assessed with formal audiology. ◆ Early identifi cation and treatment is crucial, as loss of developmental mile- stones in language cannot typically be completely regained. 4 Absence seizure ◆ Duration of seconds. ◆ Automatisms are common. ◆ Frequently associated with 3 Hz spike and wave on EEG. 5 Complex partial seizure ◆ Duration seconds to minutes. ◆ Automatisms are common. ◆ Typically preceded by aura. ◆ Post-ictal confusion and fatigue are common. Differentiating absence from complex partial seizures Clinical feature Absence seizure Complex partial seizure Aura None Typically well-defi ned Duration Seconds Seconds to minutes Post-ictal state Rare Common Automatisms Common Common Age of onset Usually childhood Usually teens to early adult Provoked by hyperventilation Common Uncommon Interictal EEG Generalized 3 Hz spike and wave Normal or with focal spikes, sharp waves, or slowing Episodic loss of consciousness • These two seizure types do share some clinical overlap. However, the distinction is usually not diffi cult to make given adequate history-taking. • Differentiating between these two seizure types is important, as their treatment, response to therapy, and prognosis is much different. • Temporary loss of consciousness may be caused by a variety of neurological, medical, psychiatric, and non-medical etiologies. • In most cases, clues to the proper diagnosis may be obtained by a careful history of the patient and observers. • Utilizing history as a guide, work-up may include tests for metabolic derangements, cardiac function, and seizures. Paroxysmal Disorders 157 1 Syncope ◆ Work-up: ECG, careful cardiac exam, pulse, and blood pressure (lying, seated, standing), consider Holter monitor, echocardiogram. 1.1 Cardiac syncope ■ Usually older patients, may occur with palpitations, chest pain. ■ Not necessarily postural, prodromal symptoms variable. 1.1.1 Ventricular tachycardia 1.1.2 Bradyarrhythmias: sick sinus syndrome, bradyarrthmia, heart block, long QT syndrome 1.1.3 Supraventricular tachycardia 1.1.4 Outfl ow obstruction: aortic stenosis 1.1.5 Reduced cardiac output: cardiomyopathy, myocardial infarction, cardiac tamponade 1.2 Neurocardiogenic syncope ■ History is very important; occurs in response to particular stimuli (see below). ■ Bradycardia during episode. 1.2.1 Vasovagal syncope ■ Most common in adolescents and young adults. ■ Associated with heightened emotional state, prolonged fast- ing, prolonged standing, hot overcrowded areas, fatigue. ■ May occur with prodromal pallor, diaphoresis. 1.2.2 Refl ex syncope: cough, micturition, Valsalva, etc. 1.2.3 Carotid sinus syncope: usually due to carotid atherosclerosis in older persons. 1.2.4 Associated with trigeminal or glossopharyngeal neuralgia. 1.3 Peripheral causes of syncope ■ May occur with prodromal pallor, diaphoresis. ■ Very often postural. ■ More common in older patients. 1.3.1 Reduced vasomotor tone 1.3.1.1 Following prolonged recumbency or sitting 1.3.1.2 Peripheral (autonomic) neuropathy 1.3.1.2.1 Diabetic neuropathy 1.3.1.2.2 Amyloid neuropathy 1.3.1.2.3 Shy-Drager: associated with Parkinsonism 1.3.1.3 Medication-induced: L-dopa, antihypertensives, anti- depressants, etc. 1.3.1.4 Following sympathectomy. 1.3.1.5 Following spinal cord injury. 1.3.2 Hypovolemia 1.3.2.1 Dehydration 158 Chapter 4 1.3.2.2 Medication-induced: diuretics 1.3.2.3 Blood loss 1.3.2.4 Addison disease 2 Metabolic 2.1 Hypoglycemia ■ Always check glucose, review medications (especially in diabetics), and assess for adequate PO intake. ■ Commonly causes ‘faintness’, less often actual loss of unconsciousness. 2.2 Hypoxia: assess oxygen saturation with pulse oximetry and arterial blood gas, exclude acute stroke and central venous thrombosis as etiology for global hypoxia, review gradient mismatch to evaluate perfusion vs. diffu- sion abnormalities. 2.3 Hyperventilation-induced alkalosis: assess with arterial blood gases. 2.4 Anemia 3 Epileptic seizure: refer to epilepsy differentials ◆ Work-up: careful history of event (particularly from witnesses); presence of risk factors (prior CNS infection or head trauma, prior seizure, family history), EEG, neuroimaging. 3.1 Absence seizure 3.2 Complex partial seizure. 3.3 Post-ictal from an unwitnessed tonic-clonic seizure. 3.4 Atonic or tonic seizure: associated with mental retardation, intractable seizures. 3.5 Myoclonic seizure: may fall to ground; consciousness usually preserved. 4 Elevated intracranial pressure: rare cause of episodic symptoms ◆ Work-up: neuroimaging, look for papilledema. ◆ Associated with severe positional headaches. ◆ May experience drop attacks: sudden falls without loss of consciousness. 4.1 Third ventricle colloid cyst 4.2 Aqueductal stenosis 5 Transient ischemic attack: vertebrobasilar insuffi ciency ◆ Uncommon cause of isolated episodic loss of consciousness. ◆ May be associated with transient brainstem symptoms. 6 Confusional migraine: more often in younger persons; associated with confusion and headache 7 Breath-holding spell: common in children; history of precipitating event 8 Psychiatric 8.1 Hysterical fainting 8.2 Panic attack ■ Symptoms include palpitations, chest pain, shortness of breath, fear. ■ No consistent postural component. ■ Presyncope is common, syncope rare. However, may lead to hyperven- tilation-induced syncope, above. Paroxysmal Disorders 159 8.3 Pseudoseizure ■ Most pseudoseizures occur in patients with true epileptic seizures also. ■ Clinical characteristics that raise suspicion (but are NOT pathogno- monic) for pseudoseizures include alternating or asynchronous motor activity, pelvic thrusting, thrashing, prolonged motor episodes with apparently preserved consciousness, no post-ictal state following a pro- longed episode, lack of stereotypy, occurrence only in the presence of others, and precipitation by emotional factors. ■ They are generally not associated with self-injury, severe falls, tongue- biting, or incontinence. ■ Video-EEG telemetry is necessary in many cases to defi nitively diagnose. Differentiating seizure from syncope Clinical observation Seizure Syncope Convulsions Common Rare Injury Common Rare Post-event confusion Common Rare Urinary incontinence Common Rare Tongue biting Common Rare Duration of aura Short Usually longer Aura Somatosensory, visceral, psychic Light-headed, dimmed vision, heart palpitations Relationship to posture No Common Metabolic etiologies of seizures • Differentiating seizure from syncope is typically not diffi cult provided accurate descriptions of the ‘spells’ themselves. This is, however, an important distinction as the treatments are markedly different. • Obtaining a description of the event from an eyewitness often provides the critical clues to allow differentiating these two phenomena. • In some series, up to 50% of all syncopal episodes are cardiac in origin. Delaying the diagnosis may prevent appropriate cardiac care for the patient. • Seizures arise as a common neurological complication of underlying metabolic disease. • Suspicion should be particularly high in the ICU setting where seizures occur in as many as 1/3 of patients. • Organ failure, especially renal, hepatic, cardiac, and pulmonary, are frequent causes of metabolic seizures. 160 Chapter 4 1 Hypoglycemia ◆ Always assess glucose levels in the setting of a seizure, review medications, and evaluate for underlying diabetes. 2 Hyponatremia ◆ Renal etiologies: diuretics, renal tubular acidosis, partial obstruction, salt wasting nephritis, SIADH. ◆ Non-renal losses: adrenal insuffi ciency, water intoxication, hypothyroidism, gastrointestinal (hyperemesis, diarrhea). 3 Hypocalcemia ◆ Remember to correct for low serum albumin. ◆ Check circulating parathyroid hormone. ◆ Common causes include: 3.1 Hyperphosphatemia (renal failure, rhabdomyolysis) 3.2 Hypovitaminosis D 3.3 Pseudohypoparathyroidism 3.4 Drugs/toxins: dilantin, phenobarbitol, citrated blood transfusions, pro- tamine, colchicine, cis-platinum, gentamycin 4 Hypomagnesemia ◆ Decreased intake: protein malnutrition, prolonged IV therapy. ◆ Decreased absorption: sprue, short gut syndrome. ◆ Excessive losses (body fl uids): gastric suctioning, intestinal/biliary fi stula, purgatives, colitis. ◆ Excessive losses (urinary): diuretics, renal failure, chronic alcoholism, pri- mary aldosterism, hypercalcemia, hyperthyroidism, renal tubular acidosis, resolving diabetic ketoacidosis. ◆ Other: iatrogenic, pancreatitis, porphyria. 5 Hepatic failure: assess ALT, AST, alkaline phosphatase and INR (PT) 6 Renal failure, uremia: can result in electrolyte perturbations as well as uremia 7 Anoxia/hypoxia: stroke, near-drowning, cardiopulmonary collapse, carbon monoxide poisoning 8 Drug/toxin-induced 8.1 Cocaine 8.2 Amphetamine 8.3 Alcohol-related • Initial work-up for metabolic derangements should include electrolyte disturbances, uremia, hyperammonemia, and hypoxia. Drug use should be excluded, especially cocaine and amphetamines, as well as alcohol withdrawal. • Seizures may be generalized tonic-clonic, complex partial, or less commonly, simple motor in nature. Paroxysmal Disorders 161 8.4 Heavy metals: rare 9 Medication-induced: penicillins, cyclosporin, FK506; rarely carbamazepine, thorazine, haloperidol 10 Nonketotic hyperglycemia 11 Inborn errors of metabolism 11.1 Porphyria: psychosis, constipation 11.2 Pyridoxine defi ciency 12 Thyroid storm: assess TSH, T3, free T4 Differentiating seizure from pseudoseizure Clinical symptom Epileptic seizure Psuedoseizure Onset Abrupt Gradual Duration Self-limited and typically <3 minutes Prolonged Semiology Usually stereotypic Thrashing, head-banging, rolling side- to-side, pelvic thrusting Course Starts and ends with minimal fl uctuation Motor activity starts and stops repeatedly Rhythmicity Rhythmic and in-phase Out-of-phase, arrhythmic, intermittent Consciousness Impaired with bilateral motor activity Preserved with bilateral motor activity Verbalization Impaired with bilateral motor activity Preserved with bilateral motor activity Post-ictal confusion Usually present Usually absent Suggestibility Absent Frequently present Headaches Approach to headache work-up Essential elements of a headache work-up • The only reliable way to differentiate between an epileptic seizure and a pseudoseizure is with video/EEG telemetry during an actual event. • Some general principles, though not without exception, are listed below. • Benign headache syndromes are common and cause signifi cant morbidity in the population. 162 Chapter 4 Important elements of the history include: 1 Location of pain including migrating and/or radiating nature. 2 Description of the pain character (sharp, dull, throbbing, lancinating). 3 Duration of pain including onset, temporal nature, and seasonal/diurnal varia- tions. 4 Severity of pain (frequently assessed on a scale from 1–10, though it is important to know whether it prevents work, normal activities, etc.). 5 Concurrent and recent medications, including the use patterns of over-the- counter analgesics. 6 Family history (migraine, seizures, psychiatric). 7 Associated symptoms or activities. 8 Precipitating, alleviating, and exacerbating features. 9 Past medical history. Examination should consist of: 1 Complete neurological exam. 2 Blood pressure, temperature, and pulse rate. 3 Point tenderness, especially involving the temporal arteries, scalp, sinuses, mus- culature of the scalp, neck, and shoulders. 4 Evaluation for papilledema, retinal hemorrhage, optic disc sharpness, and retinal venous pulsations. 5 Detection of sensory asymmetry of the scalp. Strong indications for imaging in headache • Work-up for headache consists primarily of thorough history-taking and a comprehensive neurological and physical exam. The goal is to rule out potentially serious etiologies and arrive at an accurate diagnosis for effective treatment. • Neuroimaging is not always necessary in the evaluation of headache. • Neuroimaging has a low yield in patients with migraine headaches and a normal neurological examination. • Neuroimaging has a low yield in chronic tension-type headache and normal neurological examination. • In general, focality, new onset, or signifi cant exacerbation of a previous headache pattern warrant neuroimaging. Paroxysmal Disorders 163 1 Chronic or severe headache with onset after age 50 years (CT scan with/without contrast). 2 Sudden onset, especially when described as ‘thunderclap’ or ‘worst headache of my life’ (CT scan without contrast). 3 Accelerating pattern of intensity, severity, or chronicity of previously mild head- ache (CT scan with/without contrast). 4 New headache in patient with previous diagnosis of HIV or cancer (MRI with/ without contrast). 5 Any headache which is concomitant with any focal neurological symptoms (MRI with/without contrast). 6 Persistent headache with failed management (CT with/without contrast). 7 Chronic headache with suspected sinusitis (CT scan). 8 Sudden onset of severe unilateral headache with suspected carotid or vertebral dissection and/or ipsilateral Horner syndrome (MRI/MRA). 9 New headache in patient older than 60 years. Sedimentation rate greater than 50 especially with temporal tenderness (MRI/MRA). Acute headache (usually emergency or urgent care presentation) • One of the most common complaints encountered by neurologists. However, there are only a few pathologies underlying headache that represent serious disease. • Headaches may be primary or secondary. ◆ Primary headaches have pain as the principle manifestation without known underlying disease. ◆ Secondary headaches cause pain as a manifestation of an underlying disease process (hemorrhage, tumor, etc.). • Some primary headache disorders, for example, migraine, are both acute (isolated exacerbations), and chronic (overall condition). However, it remains clinically useful to categorize headaches as acute versus chronic for the purpose of a diagnostic work-up and treatment plan. • Patient descriptors such as ‘worst’, ‘fi rst’, ‘persistent’, and ‘different’ may imply secondary headache and warrant immediate investigation, irrespective of chronicity. • Evaluation should include onset, duration, severity, character, family and patient history, location, radiation, and associated symptoms such as visual disturbances, nausea, and emesis. Important clues may also lie in precipitating, exacerbating, and alleviating features, and diurnal/seasonal variations. [...]... 179 180 181 182 Neurological disorders and associated behavioral disorders Neurological conditions that have depression as a prominent feature Neurological causes of mania Neurological conditions associated with psychosis Neurological causes of episodic dyscontrol or violence Common neurological disorders and associated behavioral disorders Substance abuse and neurological symptoms Neuro-ophthalmologic... hematoma 3.3 Vasculitis: including temporal arteritis 3 .4 Dissection: usually more acute and associated with neck pain +/– focal neurological signs 4 Intracranial infection: Epstein-Barr virus, HIV, etc 5 Pseudotumor cerebri 6 Neoplasm 7 Sinusitis 8 Temporomandibular joint (TMJ) disorder 9 Analgesic rebound headache Neurological Differential Diagnosis: A Prioritized Approach Roongroj Bhidayasiri, Michael... testing ◆ Apo-E genotyping, Aβ /tau CSF analysis 42 ◆ Electroencephalography ◆ Single-photon emission computed tomography (SPECT) ◆ Positron emission tomography (PET) Note: apolipoprotein E genotyping is not useful in isolation from the clinical criteria of Alzheimer disease, but may increase the sensitivity of the diagnosis when patients do not have the -4 allele Another biomarker for diagnosis of... for hemicrania continua G No evidence of underlying disease 4 Hemicrania continua Primary CDH: duration 48 hours) 2.1 Amnestic syndromes Head trauma Wernicke-Korsakoff syndrome... Vascular depression is a rather new term, suggesting that the late-onset depression is related to silent cerebral infarction and subcortical white matter lesions 5 Epilepsy ◆ Depression in epilepsy patients may occur as part of a prodromal emotional change, part of an aura, part of an ictal manifestation, following seizures as part of the post-ictal state and lastly, may be an interictal manifestation ◆... headache, anxiety Neuro-ophthalmologic features of common neuropsychiatric disorders • • The neuro-ophthalmologic examination may contribute essential information to neuropsychiatric diagnoses Neuro-ophthalmologic examination should include inspection, visual acuity, visual field testing, ocular motility, and fundoscopy in addition to the general neurological examination Diagnosis Neuro-ophthalmic manifestations... (see Chronic daily headache, pp 171–2) Vascular headaches: 4. 1 Chronic subdural hematoma 4. 2 Temporal arteritis 4. 3 Other vasculitides Intracranial and pericranial infection 5.1 Chronic meningitis: usually associated with altered mentation, dementia, low grade fever 5.2 Brain abscess: focal neurological signs, seizures, fever 5.3 Sinusitis 5 .4 Dental abscess: pain referred to jaw, can cause throbbing... pseudodementia In general, depression is under-recognized in neurological conditions and even when recognized, patients tend to be under-treated for depression Neurological conditions that have depression as a prominent feature 1 Multiple sclerosis ◆ Up to 80% of patients with multiple sclerosis have depressive symptoms ◆ In addition, treatment with interferon -1 b has been associated with newonset depression . head-banging, rolling side- to-side, pelvic thrusting Course Starts and ends with minimal fl uctuation Motor activity starts and stops repeatedly Rhythmicity Rhythmic and in-phase Out-of-phase,. relaxation tech- niques, cranial/cervical massage, and over-the-counter NSAIDS. 3 Sinus headache ◆ Frontal or maxillary pressure-like pain, uni- or bilateral in nature and as- sociated with. Hypothyroidism 11.3.2 Cushing syndrome 11 .4 Medication-associated 11 .4. 1 Corticosteroid withdrawal 11 .4. 2 Chronic ergot ingestion 11 .4. 3 Analgesic rebound ■ Rare in general population (4% ), but can be more than