HIV encephalitis simulating Huntington's disease.

Complications from human immunodeficiency virus (HIV)/acquired immune deficiency syndrome are notorious for mimicking other neurological diseases. We describe a case of HIV encephalitis presenting with the classic clinical features of Huntington's Disease in a woman without known HIV risk factors or other clinical stigmata suggestive of immunosuppression. This case reminds us that HIV should be part of the differential diagnosis in unexplainable neurological diseases.

Corticobasal syndrome with novel argyrophilic glial inclusions.

A 42-year-old, left-handed woman first noted impaired dexterity of the dominant hand, soon followed by dysarthria and cognitive decline. Over a 4-year period, she developed severe left-sided apraxia with eventual neglect of the left arm and progressive extrapyramidal signs. Cognitive testing showed progressive executive, visuospatial, fluency, and naming impairment with relative preservation of memory. Single-photon emission computed tomography demonstrated asymmetric right posterior frontal and superior parietal hypoperfusion. The clinical impression was corticobasal degeneration. At autopsy, severe atrophy was seen in the perirolandic and frontal regions. There was marked neuronal loss and gliosis in the posterior frontal and precentral regions and less severe pathology in prefrontal, temporal, and parietal areas. Mild to moderate gliosis and neuronal loss were also seen in the putamen, globus pallidus, subthalamic, and dentate nuclei. Gallyas silver stain revealed numerous inclusions adjacent to oligodendrocyte nuclei in white and gray matter of affected cortical and subcortical regions. The gracile inclusions were wavy, slender, and stained positively with antibodies to ubiquitin and alphaB-crystallin but not to microtubule-associated proteins (tau, MAP1B, MAP2), tubulin, neurofilaments, glial fibrillary acidic protein, or alpha-synuclein. The argyrophilic inclusions identified in this case are distinct from those previously described in neurodegenerative diseases.

Signature tau neuropathology in gray and white matter of corticobasal degeneration.

Corticobasal degeneration (CBD) is an adult-onset progressive neurodegenerative disorder characterized by L-dopa-resistant rigidity, focal cortical deficits, and variable dementia. The neuropathological hallmark of CBD is the deposition of filamentous inclusions in neurons and glia composed of hyperphosphorylated tau with only four microtubule-binding repeats (4R-tau). To characterize the regional burden of tau pathology in CBD, we studied 12 brains with the neuropathological diagnosis of CBD using biochemical and histochemical techniques. Eleven brain regions were evaluated including gray and white matter from frontal, parietal, temporal, and occipital lobes and cerebellum as well as basal ganglia. Although the distribution of tau pathology was variable, neuropathological and biochemical data showed a similar burden of tau abnormalities in frontal, temporal, and parietal lobes and basal ganglia of both hemispheres. This included abundant, sarkosyl-insoluble 4R-tau in both gray and white matter of two or more of these cortical regions and basal ganglia, and to a lesser extent, cerebellar white matter. The insoluble tau pathology in gray and white matter showed overlapping but distinct phosphorylated epitopes suggesting cell-type and subcellular localization (ie, cell bodies versus cell processes)-specific differences in tau phosphorylation. In contrast, soluble tau was composed of normal 4R/3R-tau ratios indicating no gross abnormality in tau splicing. Thus, although clinically heterogeneous, CBD is a distinct lobar and basal ganglionic tauopathy with selective aggregation of 4R-tau.