A practical guide to the management of medical emergencies - part 6 doc

324 SPECIFIC PROBLEMS: NEUROLOGICAL Subarachnoid hemorrhage TABLE 49.4 Urgent investigation in suspected subarachnoid hemorrhage CT of the brain • Blood in subarachnoid spaces • May show intracerebral hematoma Lumbar puncture if CT is normal • Raised opening pressure • Uniformly blood-stained cerebral spinal fl uid (CSF) • Xanthochromia of the supernatant (always found from 12 h to 2 weeks after the bleed; centrifuge the CSF and examine the supernatant by spectrophotometry if available; if not, compare against a white background with a control tube fi lled with water) Other investigations • Full blood count • Coagulation screen • Blood glucose • Sodium, potassium and creatinine • ECG • Chest X-ray ALERT If the CSF fi ndings are equivocal in a patient with suspected subarachnoid hemorrhage, cerebral angiography may be indicated to exclude an intracranial aneurysm: seek advice from a neurologist or neurosurgeon. CHAPTER 49 325 Subarachnoid hemorrhage TABLE 49.5 Nimodipine after subarachnoid hemorrhage • To prevent ischemic neurological defi cits, give nimodipine 60 mg 4- hourly by mouth or nasogastric tube, for 21 days • To treat ischemic neurological defi cits, give IV via a central line: 1 mg/ h initially, increased after 2 h to 2 mg/h if no signifi cant fall in blood pressure. Continue for at least 5 days (max. 14 days) • Other calcium-channel blockers and beta-blockers should not be given while the patient is receiving nimodipine TABLE 49.6 Monitoring and supportive care after subarachnoid hemorrhage • Admit the patient to ITU/HDU • Monitor conscious level (Glasgow Coma Scale score, see Table 46.2), pupils, respiratory rate, arterial oxygen saturation, heart rate, blood pressure, temperature, fl uid balance and blood glucose, initially 2–4-hourly • Give analgesia as required (e.g. paracetamol 1 g 6-hourly and/or codeine 30–60 mg 4-hourly PO). Add a benzodiazepine if needed for anxiety. Start a stool softener to prevent constipation • Ensure an adequate fl uid intake to prevent hypovolemia: initially 3 L normal saline IV daily. Check electrolytes and creatinine at least every other day • If conscious level is reduced, place a nasogastric tube for feeding • Use graduated compression stockings to reduce the risk of DVT • Antihypertensive therapy is not of proven benefi t in preventing rebleeding and may cause cerebral ischemia. If hypertension is sustained and severe (systolic BP >200 mmHg, diastolic BP >110 mmHg), despite adequate analgesia, cautious treatment may be given, e.g. metoprolol initially 25 mg 12-hourly PO: discuss with neurosurgical unit DVT, deep vein thrombosis; HDU, high-dependency unit; ITU, intensive therapy unit. 326 SPECIFIC PROBLEMS: NEUROLOGICAL Subarachnoid hemorrhage Further reading Suarez JI, et al. Aneurysmal subarachnoid hemorrhage. N Engl J Med 2006; 354: 387–96. Van Gijn J, et al. Subarachnoid haemorrhage. Lancet 2007; 369: 306–18. TABLE 49.7 Causes of neurological deterioration after aneurysmal subarachnoid hemorrhage • Recurrent hemorrhage: peak incidence in the fi rst 2 weeks (10% of patients) • Vasospasm causing cerebral ischemia or infarction: peak incidence between day 4 and day 14 (25% of patients) • Communicating hydrocephalus: from 1 to 8 weeks after the hemorrhage (15–20% of patients) • Seizures • Hyponatremia, due to either inappropriate ADH secretion (p. 442) or cerebral salt wasting Bacterial meningitis 50 Bacterial meningitis 327 Yes No Yes No Yes No Yes No Suspected bacterial meningitis Two or more of: • Headache • Fever • Neck stiffness • Reduced conscious level Key observations (Table 1.2) Stabilize airway, breathing and circulation Focused assessment (Table 50.1) Urgent investigation (Table 50.2) Shock? Antibiotic therapy (Table 50.3) Call resuscitation team See p. 60 for further management of septic shock Indications for CT scan before lumbar puncture (LP) (Table 50.1) or coagulopathy? Antibiotic therapy (Table 50.3) Consider dexamethasone (Table 50.4) Correct coagulopathy CT scan LP still contraindicated? Continue antibiotic therapy + dexamethasone Seek advice from infectious diseases physician/neurologist Supportive care (Table 50.5) Do lumbar puncture (p. 627) Cerebrospinal fluid consistent with bacterial meningitis? (Table 97.3) Antibiotic therapy (Table 50.3) Consider dexamethasone (Table 50.4) Seek advice from microbiologist Supportive care (Table 50.5) Pursue other diagnoses (Tables 50.6, 50.7, 51.3) 328 SPECIFIC PROBLEMS: NEUROLOGICAL Bacterial meningitis TABLE 50.1 Focused assessment in suspected bacterial meningitis 1 Is this meningitis? • Consider meningitis in any febrile patient with headache, neck stiffness or a reduced conscious level • Disorders which can mimic meningitis include subarachnoid hemorrhage (p. 321), viral encephalitis (p. 334), subdural empyema, brain abscess and cerebral malaria (p. 546) 2 Is immediate antibiotic therapy indicated? • If the clinical picture suggests meningitis, and the patient has shock, a reduced conscious level or a petechial/purpuric rash (suggesting meningococcal infection), take blood cultures (×2) and start antibiotic therapy (Table 50.3), plus adjunctive dexamethasone (Table 50.4) if indicated 3 Should a CT scan be done before lumbar puncture? • CT should be done fi rst if there are risk factors for an intracranial mass lesion or signs of raised intracranial pressure: – Immunocompromised state (e.g. AIDS, immunosuppressive therapy) – History of brain tumor, stroke or focal infection – Fits within 1 week of presentation – Papilledema – Reduced conscious level (Glasgow Coma Scale score <10) – Focal neurological signs (not including cranial nerve palsies) • If CT is needed, take blood cultures (×2) and start antibiotic therapy (Table 50.3), plus adjunctive dexamethasone (Table 50.4) if indicated CHAPTER 50 329 Bacterial meningitis TABLE 50.2 Urgent investigation in suspected meningitis • Blood culture (×2) • Throat swab • Lumbar puncture (preceded by CT if indicated, Table 50.1) • Full blood count • Coagulation screen if there is petechial/purpuric rash or low platelet count • C-reactive protein • Blood glucose • Sodium, potassium and creatinine • Arterial blood gases and pH • Chest X-ray TABLE 50.3 Initial antibiotic therapy for suspected bacterial meningitis in adults (IV, high dose) Setting No penicillin allergy Penicillin allergy Previously healthy Cefotaxime or Minor allergy: adult under 50 ceftriaxone cefotaxime or ceftriaxone Severe allergy: chloramphenicol Age over 50 Cefotaxime or Minor allergy: Immunocompromised ceftriaxone + cefotaxime or (organ transplant, ampicillin or ceftriaxone lymphoma, steroid amoxycillin Severe allergy: therapy, AIDS) chloramphenicol Chronic alcohol abuse ALERT Discuss further antibiotic therapy with a microbiologist in the light of the clinical picture and cerebrospinal fl uid results. 330 SPECIFIC PROBLEMS: NEUROLOGICAL Bacterial meningitis TABLE 50.4 Adjunctive dexamethasone in suspected bacterial meningitis Indications • Strong clinical suspicion of bacterial meningitis, especially if CSF is turbid Contraindications • Antibiotic therapy already begun • Septic shock • Suspected meningococcal disease (petechial/purpuric rash) • Immunocompromised (e.g. AIDS, immunosuppressive therapy) Regimen • Give dexamethasone 10 mg IV before or with the fi rst dose of antibiotic therapy (Table 50.3) • Continue dexamethasone 10 mg 6-hourly IV for 4 days if CSF shows Gram-positive diplococci, or if blood/CSF cultures are positive for Streptococcus pneumoniae CSF, cerebrospinal fl uid. TABLE 50.5 Supportive treatment of bacterial meningitis Element Comment Airway, breathing and Manage along standard lines (Tables 1.3–1.7) circulation In patients with septic shock, give low-dose steroid (hydrocortisone 50 mg 6-hourly IV + fl udrocortisone 50 µg daily IV) Raised intracranial Manage along standard lines (p. 362) pressure Continued CHAPTER 50 331 Bacterial meningitis Element Comment Fluid balance Insensible losses are greater than normal due to fever (allow 500 ml/ day/°C) and tachypnea Give IV fl uids (2–3 L/day) with daily check of creatinine and electrolytes if abnormal on admission Hyponatremia may occur due to inappropriate ADH secretion (p. 441) Monitor central venous pressure and urine output if patient is oliguric or if plasma creatinine is >200 µmol/L DVT prophylaxis Give DVT prophylaxis with stockings and LWH heparin Prophylaxis against gastric Give proton pump inhibitor stress ulceration Fits Manage along standard lines (p. 349) Prophylactic anticonvulsant therapy not indicated ADH, antidiuretic hormone; DVT, deep vein thrombosis; LMW, low molecular weight. TABLE 50.6 Tuberculous (TB) meningitis Element Comment At risk groups Immigrants from India, Pakistan and Africa Recent contact with TB Previous pulmonary TB Chronic alcohol abuse IV drug use Immunocompromised (organ transplant, lymphoma, steroid therapy, AIDS) Continued 332 SPECIFIC PROBLEMS: NEUROLOGICAL Bacterial meningitis Element Comment Clinical features Subacute onset Cranial nerve palsies Retinal tubercles (pathognomonic but rarely seen) Hyponatremia Chest X-ray often normal CT Commonly shows hydrocephalus (∼75%) May show cerebral infarction due to arteritis (∼15–30%) May show tuberculoma (∼5–10%) Cerebrospinal High lymphocyte count fl uid (CSF) High protein concentration Acid-fast bacilli may not be seen on Ziehl–Neelsen stain Mycoplasma tuberculosis DNA may be detected in CSF by the polymerase chain reaction Treatment Combination chemotherapy with isoniazid (with pyridoxine cover), rifampicin, pyrazinamide and ethambutol or streptomycin Consider adjunctive dexamethasone Seek expert advice TABLE 50.7 Cryptococcal meningitis Element Comment At risk groups Immunocompromised (organ transplant, lymphoma, steroid therapy, AIDS) Clinical features Insidious onset Headache usually major symptom Neck stiffness absent or mild CT Usually normal May show hydrocephalus May show mass lesions (∼10%) Continued CHAPTER 50 333 Bacterial meningitis Further reading British Infection Society. Early management of suspected bacterial meningitis and meninogococcal septicaemia in immunocompetent adults (2005). British Infection Society website (http://www.britishinfectionsociety.org/meningitis.html). Ginsberg L. Diffi cult and recurrent meningitis. J Neurol Neurosurg Psychiatry 2004; 75 (suppl I): i16–i21. Van de Beek D, et al. Community-acquired bacterial meningitis in adults. N Engl J Med 2006; 354: 44–53. Element Comment Cerebrospinal Opening pressure usually markedly raised, fl uid (CSF) especially in patients with AIDS Raised lymphocyte count (20–200/mm 3 ) Protein and glucose levels usually only mildly abnormal Cryptococci may be seen on Gram stain India ink preparation positive in 60% CSF culture positive Serological tests for cryptococcal antigen on CSF or blood positive Treatment Amphotericin plus fl ucytosine Seek expert advice [...]... Progression of underlying structural brain lesion (e.g glioma) T A B L E 55 4 Maintenance antiepileptic therapy Seizure type First-line drugs Second-line drugs Third-line drugs Generalized at onset Lamotrigine Valproate* Levetiracetam Topiramate Acetazolamide Clonazepam Phenobarbital Clobazam Focal at onset Carbamazepine Lamotrigine Valproate* Gabapentin Levetiracetam Pregabalin Tiagabine Zonisamide Acetazolamide... compression Transverse myelitis Anterior spinal artery occlusion Hematomyelia Poliomyelitis Rabies Continued Guillain–Barré syndrome • Transfer to HDU/ITU if: – Vital capacity . Guillain–Barré syndrome in any patient with paresthesiae in the fi ngers and toes or weakness of the arms and legs. Respiratory failure and autonomic instability are the major complications. . Personality change/abnormal behavior Alteration in conscious level Fits Focal neurological abnormalities (cranial nerve palsies, dysphasia, hemiparesis, ataxia) CT May be normal May show. CSF by the polymerase chain reaction EEG Abnormal in two-thirds of cases, with a spike and slow wave pattern localized to the area of brain involved Treatment Aciclovir 10 mg/kg 8-hourly