Table 1.
DISTINGUISHING FEATURES OF NEUROLOGIC DISORDERS ASSOCIATED WITH HIV INFECTION
| Etiology | CD4 Count (cells/mm3) | Common Clinical Features | Neuroimaging Findings by MRI or CT Scanning | Diagnosis |
|---|---|---|---|---|
| Fungal Infections | ||||
| Cryptococcal meningitis | <200 | Fever; bilateral headache; altered mental status; meningeal signs (photophobia, nuchal rigidity) | Normal; meningeal enhancement or enhancing lesion (cryptococcoma) may be present | Presence of CrAg in serum and CSF; positive CSF culture of C. neoformans; positive CSF india ink test |
| Parasitic Infections | ||||
| Toxoplasma encephalitis | <200 | Fever; unilateral or bilateral headache; altered mental status; seizures; focal neurologic deficit: hemiparesis, ataxia, facial weakness | Solitary or multiple ring-enhancing lesions located in the basal ganglia, deep white matter or hemispheric grey-white junction; MRI more sensitive than CT scanning and may detect more lesions | Serum anti-Toxoplasma IgG antibody usually present; definitive diagnosis by identification of trophozoiites on brain biopsy, but presumptive diagnosis by radiologic and clinical improvement after 10–14 days of anti-Toxoplasma therapy |
| Viral Infections | ||||
| Progressive multifocal leukoencephalopathy (JC Virus) | <100 | Unilateral or bilateral headache; visual field deficit; subacute onset of hemiparesis or other focal neurologic deficits; seizures | Solitary or multiple nonenhancing white matter lesions on CT scanning or MRI; lesions most often in parieto-occipital region; on MRI, lesions hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging | CSF PCR for JC virus is sensitive and specific; brain biopsy |
| Primary CNS Lymphoma (Epstein-Barr Virus) | <100 | Unilateral or bilateral headache; focal neurologic deficit; seizures | Solitary or multiple ring- or homogeneously enhancing lesions; may see nodular ventricular lesions or lesions that cross the midline | CSF PCR for Epstein-Barr virus is sensitive and specific; brain biopsy |
| AIDS dementia complex | <200 | Impaired memory and concentration; psychomotor slowing; apathy or withdrawal | Atrophy; on CT scanning diffuse white matter hypodensity; on MRI white matter hyperintense on T2-weighted imaging; no contrast-enhancing lesions | Clinical diagnosis; CSF β2 microglobulin >3.8 mg/l specific, but not sensitive |
| Bacterial Infections | ||||
| M. tuberculosis of CNS | Any | Insidious onset of headeache, fever, and malaise, followed by meningismus, cranial nerve deficits, and mental status changes. Involvement of intracranial arteries may result in stroke. | Ring-enhancing or nonenhancing lesions, or normal. Patients with focal lesions without focal neurologic signs are more likely to have TE than CNS TB. HIV-infected people more often have intracerebral mass lesions. | CSF notable for lymphocytic pleocytosis, hypoglycorrhachia, increased protein, or elevated ADA. AFB smear positive in 37% of initial CSF exam, but 87% if four serial CSF samples examined. Anergy to tuberculin skin testing is common |