GBL3 11/27/03 3:43 PM Page 17 CHAPTER 3 Neurological Presentations Rapid assessment of patient Indications and Further reading, 25 with coma in the tropics, 19 contraindications for lumbar Classification and further puncture in suspected CNS investigation of patients with infections,24 coma, 23 Neurological presentations are more common prevention are important. These may lead, in the tropics than in the developed industrial for example, to cysticercosis and typhoid. world. Infectious diseases make a major contri- • Immunosuppression, particularly as a result bution, but non-infectious causes are also im- of HIV, allows many other infections such as portant (Table 3.1). A complex mixture of cryptococcal and tuberculous meningitis. socioeconomic and environmental factors contribute to the increased incidence. Neurological syndromes Neurological diseases — particularly infections Reasons for increased incidence — can present with a range of syndromes. of neurological disorders in • Encephalopathy — a reduced level of con- the tropics sciousness from any cause (infectious, metabo- • Non-infectious neurological disorders — lic, vascular, traumatic). trauma is more common in the tropics, espe- • Meningism — clinical signs of meningeal irrita- cially road traffic accidents. Patterns of vascular tion (headache, neck stiffness, Kernig’s sign; see disease are catching up with those in the devel- below). oped world, but the usage of drugs to control • Paralysis — weakness of one or more limb, res- them lags behind. piratory or bulbar muscles, which may be a • Infectious neurological diseases — the climate result of damaged upper motor neurones, supports transmission of insect-borne patho- lower motor neurones, peripheral nerves, or gens (malaria, trypanosomiasis, arthropod- muscles. borne viruses). Environmental factors include • Chronic neurological presentations — insidious the close proximity of homes to zoonotic infec- presentation over weeks or months, often with tions. Vaccine-preventable diseases are more changes in personality, behaviour or other psy- common (e.g. measles, tetanus, diphtheria, chiatric illness. Fever may not be prominent, polio). There is also unregulated use of over- even with an infectious cause (Table 3.2). the-counter antibiotics, leading to the partial • Headache — may be the only symptom (e.g. in pretreatment of central nervous system (CNS) cryptococcal meningitis). infections, which hampers diagnosis and thera- • Other focal neurological signs — including hemi- py, and promotes the development of antibiotic spheric signs, brainstem signs, seizures and resistance. movement disorders. •Poverty, overcrowding, poor sanitation and lack of education about disease risk factors and 17 GBL3 11/27/03 3:43 PM Page 18 18 Chapter 3: Neurological Presentations CAUSES OF NEUROLOGICAL DISEASE Vascular Endemic/murine/flea-borne typhus (R. Ischaemia/infarct typhi/R. mooseri) Subarachnoid/subdural/extradural/ Scrub typhus (O. tsutsugamushi) intracerebral haemorrhage Rocky Mountain spotted fever (R. rickettsii) Hypertension/hypotension Fungi Cryptococcosis Infectious Histoplasmosis Direct effect on CNS Aspergillosis Bacteria Coccidioidomycosis Meningococcus, streptococci, Haemophilus Candidiasis influenzae, tuberculosis, leprosy Paracoccidiomycosis Viruses Blastomycosis Arboviruses, herpes viruses, enteroviruses, Nocardiasis* rabies Parasites Indirect effect of infection Protozoans Toxin-mediated infectious diseases (tetanus, malaria (Plasmodium falciparum) diphtheria, shigellosis) African trypanosomiasis (Trypanosoma Immune-mediated postinfectious gambiense and T. rhodesiense) inflammatory (GBS, acute disseminated toxoplasmosis (Toxoplasma gondii) encephalomyelitis) amoebiasis (Entamoeba histolytica) Trematodes (flukes) Metabolic paragonimiasis Hypoglycaemia schistosomiasis (especially Schistosoma Diabetic ketoacidosis japonicum) Hepatic encephalopathy Cestodes (tapeworms) Uraemia cysticercosis (Taenia solium) Hyponatraemia hydatidosis (Echinococcus granulosus) Hypothyroidism/hyperthyroidism Nematodes (roundworms) Addison’s disease ascariasis (Ascaris lumbricoides) parastrongyliasis (Parastrongylus Tumours/trauma/toxins cantonensis) Alcohol gnathostomiasis Drugs (medical, recreational, traditional) trichinosis (Trichinella spiralis) Pesticides Spirochetes Poisons Neurosyphilis (Treponema pallidum) Lyme disease (Borrelia burgdorferi) Other Leptospirosis (Leptospira species) Hydrocephalus Louse-borne/epidemic relapsing fever (B. Epilepsy recurrentis) Psychiatric disease (hysteria) Tick-borne/endemic relasing fever (B. duttonii) Inflammatory Rickettsiae Nutritional Epidemic/louse-borne typhus (Rickettsia Degenerative prowazekii) Abbreviations: CNS, central nervous system; GBS, Guillain–Barré syndrome. *Nocardia are actinomycete bacteria which are grouped with fungi because of their morphology and behaviour. Table 3.1 Causes of neurological disease (VIMTO). GBL3 11/27/03 3:43 PM Page 19 Rapid assessment of patient with coma in the tropics 19 CHRONIC NEUROLOGICAL PRESENTATIONS Infectious Other Sleeping sickness (especially Trypanosoma rhodesiense,Tumours T. gambiense) Tuberculous meningitis Chronic subdural haemorrhages HIV encephalopathy Lead, other heavy metal poisoning Toxoplasma gondii and other parasitic space-occupying lesions Dementia Bacterial abscesses Vitamin deficiencies Partially treated bacterial meningitis Drugs Neurosyphilis Toxins Cryptococcal meningitis and other fungi Subacute sclerosing panencephalitis Table 3.2 Causes of chronic neurological presentations in the tropics. CNS SPACE-OCCUPYING LESIONS Tumours and metastases Pathological processes Haemorrhage These neurological syndromes are explained by Bacterial abscesses a range of pathological processes. Tuberculomas • Encephalitis — inflammation of the brain sub- Parasites stance, usually in response to viral infection, but Protozoa (toxoplasmosis, amoebiasis) Trematodes (paragonimiasis, also in response to other pathogens. schistosomiasis) • Meningitis — inflammation of the meningeal Cestodes (cysticercosis, hydatidosis) membranes covering the brain, in response to Nematodes (ascariasis) bacterial, viral or fungal infection. Fungi • Myelitis — inflammation of the spinal cord.This Aspergillosis, blastomycosis, nocardiasis may occur across the whole cord (causing transverse myelitis, which is often postinfec- Table 3.3 Causes of central nervous system tious) or be confined to the anterior horn cells. space-occupying lesions in the tropics. • Neuropathy — damage to peripheral nerves (e.g. Guillain–Barré syndrome, diphtheria, lep- •Airways. rosy, rabies, vitamin deficiencies). •Breathing — give oxygen; intubate if breath- • Space-occupying lesions (Table 3.3) — these ing is inadequate or gag reflex impaired. cause pathology in the brain or spinal cord di- • Circulation — establish venous access. rectly (by interrupting neuronal pathways), and Obtain blood for immediate bedside blood indirectly (by causing localized swelling, raised glucose test (hypoglycaemia?). intracranial pressure and brainstem herniation Malaria film (look for parasites and pigment syndromes). Typically, they present with focal of partially treated malaria). signs or a chronic insidious deterioration. FBC, U&E, blood cultures, arterial blood gases. • Disability. Rapid assessment of patient Give intravenous (i.v.) glucose (e.g. 10% with coma in the tropics glucose 50·mL in adults, 5·mL/kg in children), irrespective of blood glucose. 1 Stabilize the patient, and treat any imme- Give adults 100·mg thiamine i.v., especially if diately life-threatening conditions. alcohol abuse is suspected. GBL3 11/27/03 3:43 PM Page 20 20 Chapter 3: Neurological Presentations Immobilize cervical spinal cord if neck trau- • Note temperature (febrile or hypother- ma is suspected. mia) and blood pressure (hypo- or hyperten- •Rapidly assess AVPU scale (alert, responds sive). to voice, to pain, or unresponsive). • Examine for signs of trauma (check ears If patient responds to pain or is unresponsive, and nose for blood or cerebrospinal fluid examine the pupils, eye movements, respira- (CSF) leak). tory pattern, tone and posture for signs of • Smell the breath for alcohol or ketones cerebral herniation (see below). (diabetes?). If herniation is suspected start treatment for • Examine the skin for: this. rash (meningococcal rash, dengue or other • If purpuric rash is present give penicillin haemorrhagic fever, typhus, relapsing or chloramphenicol (or third generation fever); cephalosporin) for presumed meningococcal needle marks of drug abuse; meningitis (after taking blood cultures). recent tick bite or eschar (tick-borne en- • Look for and treat generalized seizures, cephalitis, tick paralysis, tick-borne typhus focal seizures and subtle motor seizures or relapsing fever); (mouth or finger twitching, or tonic eye devi- chancre, with or without circinate rash ation). (trypanosomiasis, especially Tr ypanosoma 2Take a history, while preliminary assess- rhodesiense); ment and resuscitation proceeds.This is the sin- healed dog bite (rabies); or gle most useful tool in determining the cause of snake bite. coma. In particular: • Examine for lymphadenopathy (e.g. • Duration of onset of coma. Winterbottom’s sign of posterior cervical Rapid onset (minutes–hours) suggests a lymphadenopathy in African trypanosomiasis). vascular cause, especially brainstem • Examine the fundi for papilloedema (long- cerebrovascular accidents or subarach- standing raised intracranial pressure) or signs noid haemorrhage. If preceded by hemi- of hypertension.