Movement Disorders in Tropical Infectious Diseases.

purpose of reviewTo review various types of movement disorders associated with common tropical infectious diseases produced by viruses, bacteria, rickettsia, protozoa and/or parasites. At times, the offending organism almost exclusively affects the central nervous system (CNS) without any significant systemic manifestations, as in neurocysticercosis. RECENT

findingsMovement disorders almost invariably result from direct invasion of the CNS by the offending organism. CNS involvement may occur as a result of brain edema, electrolyte abnormalities, hypoxia, ischemia, haemorrhage, liver and kidney malfunction and/or due to liberation of toxic substances like cytokines and enzymes. Such encephalopathies rarely result in prominent movement disorders other than tremors Finding the exact cause and nature of the causative organism is of utmost importance. Nucleic acid in vitro amplification-based molecular methods are increasingly being applied for routine microbial detection. Advantages are a rapid turnaround and higher sensitivity and specificity. Furthermore, these molecular methods performed on cerebrospinal fluid (CSF) samples may be considered as the ‘’new gold standard’’ for diagnosis of CNS infection. Commercially available ‘’panels’’ offer various multiplex PCR assays for convenient testing of targets that cause similar clinical scenarios. Pan-omics molecular platforms possess potential for use in this area. Results generated by these methods need to be carefully interpreted in combination with clinical findings. Using a combination of conventional and molecular diagnostic methods, it has been shown that in approximately two thirds of patients with clinical encephalitis, an etiologic organism could not be identified. Current practice is shifting towards development of advanced techniques beyond nucleic acid-based detection. CSF is the ideal specimen for PCR testing in patients with suspected meningitis or meningoencephalitis. Time of testing from symptom onset is essential to understand and rule out false negative results and recommend retesting within a certain time frame (as in cases of HSV encephalitis). Immunocompromised patients are at risk for infection by a much wider strains of opportunistic pathogens, for example HHV-6, JC virus, Toxoplasma encephalitis among bone marrow transplant recipients and patients with HIV. Often, infection can be more severe (e.g., West Nile Virus) and difficult to diagnose. Nucleic acid in vitro amplification-based molecular diagnosis methods have a wider and better application in clinical microbiology practice. Movement disorders including cerebellar ataxias are rare during any acute encephalitic syndrome (AES). Such disorders may develop after the acute infection as transient phenomenon when they resemble the pathogenesis of acute disseminated encephalomyelitis (ADEM) or may result from permanent brain damage during the acute course of the illness. CSF pleocytosis generally favours an infectious etiology, and a normal CSF favors an encephalopathy or non-infectious AES. Geographical and seasonal clustering and other epidemiological characteristics are important in clinical decision making. Clinical markers like eschar, skin rash, myalgias, hepatosplenomegaly, thrombocytopenia, liver and kidney dysfunction, elevated serum CK, frontal-temporal or thalamic involvement, or anterior horn cell involvement are invaluable clues for the etiological diagnosis.