Tuberculoma with Tubercular Meningitis

October 21, 2014

Case History: 12-year-old female presented with fever, altered sensorium, and seizures over a six week period.

Case History: 12-year-old female presented with fever, altered sensorium, and seizures over a six week period. MRI with contrast shows marked leptomeningeal enhancement, shaggy tentorial enhancement, enhancing basal exudates, and multiple conglomerate ring enhancing lesions in cerebellum. Obstructive hydrocephalus is also noted.

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Figure 1. FLAIR image shows hydrocephalus with periventricular flare.

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Figure 2. FLAIR image shows hyperintese signal in cerebellum s/o edema.

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Figure 3. T2W image shows hyperintense signal in cerebellum s/o edema.

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Figure 4. A-C, Multiple enhancing nodules seen in cerebellum and leptomeningeal enhancement in tentorial cerebella region. D, Enhancing nodule in cortical region in right parietoocipital region.

Tuberculous Meningitis
Tuberculous meningitis is the most common presentation of intracranial tuberculosis, and can either involve the leptomeninges (most common) or be limited to the pachymeninges. Tuberculous pachymeningitis is discussed separately.

Epidemiology
Tubeculous meningitis, although seen in all age groups, has a peak incidence in childhood (particularly 0–4 years of age) in high prevalence areas. In low prevalence areas, it is more frequently encountered in adolescents and adults.

Important risk factors include:

• HIV / AIDS
• Immunosuppression
• Diabetes mellitus
• Alcoholism

Pathology
Tuberculous meningitis is caused by Mycobacterium tuberculosis. The infection spreads hematogeneously from a distant focal point, usually pulmonary tuberculosis and lodges immediately deep to the pia forming rich foci. These can rupture into the subarachnoid space, forming an exudate. This purulent material is primarily located in vicinity of basal cisterns: inferomedial surface of frontal lobe, anteromedial surface of temporal lobes, superior cerebellum, and floor of the fourth ventricle. From here, infection spreads to interpeduncular cisterns, around optic chiasm and to pontomesencephalic, ambient, and suprasellar cisterns. Although the exudate can reach the Sylvian fissures, it uncommonly extends over the cerebral convexities . Choroid plexitis may also be a late manifestation as is mass-like regions of caesous necrosis within this exudate. Complications include an arteritis which may result in ischaemic infarcts. This is seen in approximately one-third of cases, and is more common in children. Obstructive hydrocephalus is common.

Clinical Presentation
Low-grade fever with headache is prodromal manifestation. The most common clinical manifestations are fever, headache, vomiting, and neck stiffness. Cranial nerve palsies of 3rd, 4th, and 6th nerves may be seen. Seizures, focal neurological deficits, stupor, and coma may be seen in late stages. CSF analysis reveals lymphocytosis, increased protein levels, and decreased glucose levels.

Radiographic FeaturesCT
• Noncontrast scans may be normal.
• Later complications may be visible including:

• Hydrocephalus
• Infarcts due to arteritis (especially in children)

Following contrast administration a number of additional features may be visible:
• Basal enhancing exudates.
• Leptomeningeal enhancement, along sylvian fissures, tentorium uncommonly convexities. • Ependymitis may be present.

MRI
• T1

• normal initially
• T1 shortening may be seen after progression of disease

• T2

• normal initially
• T2 shortening is seen after disease progression

• T1 C+ (GAD): diffuse basal enhancement with enhancing exudates.
• Magnetization transfer (MT) spin echo: significantly lower MT ratio is seen in tuberculous meningitis as compared to fungal and pyogenic meningitis.

Complications
• Hydrocephalus (usually communicating hydrocephalus). • Arteritis and infarcts. • Cranial neuropathies: most affected nerves are 3rd, 4th, and 6th nerves

Treatment and Prognosis
Anti-tuberculosis regimen is started after confirmation of diagnosis. Treatment of complications (e.g., drainage of hydrocephalus) is also performed.

Differential Diagnoses
• Pyogenic meningitis.
• Leptomeningeal carcinomatosis.
• Fungal meningitis.

• A tuberculoma or tuberculous granuloma is a well defined focal mass that results from infection with mycobacterium tuberculosis, and is one of several morphological forms of tuberculous disease. Tuberculomas occur most commonly in the brain and lung.

Pathology

• Macroscopically, a tuberculoma is a well defined firm nodule. Histologically, it consists of a central core of caseating necrosis with a surrounding wall of a granulomatous reaction containing Langhans giant cells, epithelioid histiocytes, and lymphocytes.