Endemic Infection: Lying in Wait

History and Physical

An 11-year-old boy presented with a low-grade fever for one month, followed by headache for the past 15 days and altered sensorium over the past week. On day 15 of fever, he experienced an episode of transient right-sided weakness that resolved within 24 hours. The headache was occasionally associated with projectile vomiting and transient relief. Patient and family history were noncontributory.

Clinical examination showed normal vital signs and anthropometry. Blood pressure in supine position was mildly elevated for age. The patient appeared sleepy but arousable. He had neck stiffness, Brudzinski sign, and bilateral Kernig signs. There was no papilledema, restriction of eye movement, facial or motor weakness. The rest of the systemic examination was unremarkable, without organomegaly or lymphadenopathy.

Diagnostic Workup

Lumbar puncture showed elevated CSF pressure with 179 cells (lymphocytes), normal glucose (63 mg/dL), elevated protein (97 mg/dL), and absence of acid-fast bacilli on Ziehl-Neelsen staining. Gram stain, bacterial cultures, and PCR for mycobacterium were negative. Intradermal Mantoux skin test was reactive and showed an induration of 15 × 15 mm. Serology for HIV was negative.

Head CT showed bilateral basal ganglia infarcts, basal exudates, hydrocephalus, and cerebellar tuberculomas ( Fig. 40.1 ). Brain MRI with contrast revealed thick meningeal enhancement along the basal cisterns and bilateral cerebral convexities, basal ganglia infarcts, and moderate obstructive hydrocephalus ( Fig. 40.2 ).

A five panel brain M R I series shows sagittal, axial, and coronal views with widespread signal abnormality and reduced brain volume. The set of five brain M R I panels shows different views in a six month old child. Panel A is a sagittal T1 weighted image showing a thin corpus callosum and enlarged subarachnoid spaces, consistent with reduced brain volume. Panel B is an axial T2 weighted image showing diffuse high signal in the white matter across both hemispheres, indicating absence of normal myelin. Panel C is another axial T2 image showing abnormal white matter signal in the brainstem and cerebellum. Panel D is an axial T1 weighted image with poor myelination and prominent sulci, reflecting cerebral atrophy. Panel E is a coronal T2 weighted image showing hyperintense white matter in the cerebrum and cerebellum with widened fissures and enlarged ventricles. All panels show consistent findings of global brain atrophy and diffusely abnormal white matter signal. — Fig. 40.1

A two panel brain M R I shows axial T1 and T2 views with delayed and uneven white matter signal marked by arrowheads. The set of two axial brain M R I images shows findings in a 15 month old child. Panel A on the left is a T1 weighted image that shows reduced and uneven signal in the cerebral white matter, indicating delayed myelination. The ventricles and basal ganglia appear structurally preserved. Panel B on the right is a T2 weighted image showing patchy high signal in the periventricular and subcortical white matter, marked by arrowheads on both hemispheres. The myelination appears incomplete and asymmetrical. The cortex, ventricles, and deep gray structures are clearly visualized. Both panels highlight delayed and heterogeneous white matter development without any additional labels or annotations. — Fig. 40.2

Clinical Differential Diagnosis

Chronic neurologic symptoms with fever, increased ICP, and meningismus can be seen in:

Infection: Tuberculosis, HIV with opportunistic infections, cryptococcosis, neurobrucellosis, invasive fungal infection, granulomatous amebic encephalitis in an immunocompromised host
Vascular: CNS vasculopathies
Tumors: primary CNS malignancies and metastases

Imaging Differential Diagnosis

Meningeal enhancement: Tuberculosis, sarcoidosis, IgG4-related disease, leptomeningeal carcinomatosis.
Basal exudates: Tuberculosis, neurobrucellosis, granulomatous amebic encephalitis.
Hydrocephalus: Meningitis, tumors, aqueductal stenosis.