Neurological Disorders: Brain Toxoplasmosis

Introduction

Brain Toxoplasmosis is nothing but infection of the brain with a parasite by name toxoplsma gondii, and this condition mostly occurs in people with compromised immune system. Another important set up where this type of infection can occur is when a baby is exposed to this organism in the intrauterine life during the pregnancy.

In immunocompetent people toxoplasmosis infection is not a concern most often. But in the immunocompromised people (e.g. AIDS patients) and fetus this is a serious infection. In adults this is considered as an opportunistic infection because of the above reason. Brain & eyes are the two organs most commonly involved in both adults and children.

How does this disease develop?

Fetus acquires the infection through the infected mother. It is still not entirely clear how exactly during the extra uterine life this parasite gains access to the gastrointestinal tract, however generally thought to be acquired from the fecal mater of the cat or eating under boiled meat of animals like lamb. The larval form of the parasite penetrates through the intestinal wall and enters the organs and tissues like brain, eyes, multiply there and produce the disease.

How do patients present?

Involvement of the brain causes encephalitis, multifocal lesions, rarely meningitis or meningoencephalitis pattern. Children born with toxoplasmosis show calcification in the brain, microcephaly (small skull), mental retardation seizure, visual problems etc. It is pat of the TORCH infection of the fetus where T stands for infection due to Toxoplasma.

In adults seizures, headache, fever, change in mental status, focal neurological manifestations like limb paralysis, sensory deficits etc are common.

If untreated it is rapidly fatal in immnocompromised adults.

Diagnosis of Toxoplasmosis

The following investigations are usually employed;

• CT and/or MRI of the brain with & without contrast
• Serum and spinal fluid IgG & IgM antibodies
• SPECT scan of the brain
• Therapeutic diagnosis (explained below)
• Brain biopsy etc

In AIDS patients both toxoplasmosis and CNS lymphoma are common. Generally toxoplasmosis presents with multiple lesions where as lymphoma presets with single or only few lesions. Once we suspect toxoplasmosis then treatment should be started at the earliest. If toxoplasmosis is present then majority of the brain lesions improve in about 1 to 2 weeks, but if no such improvement is seen or rather a progression of the lesions is seen then a brain biopsy is indicated.

Treatment

Pyrimethamine + sulfadiazine combination for prolonged periods followed by maintenance therapy for future recurrence is the mainstay of the treatment. Clindamycn, spiramycin etc are some alternatives.

Seizures are treated with anti seizure medications.

A neurologist is frequently involved in the care of patients with Brain Toxoplasmosis.



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