Umberto DeGirolami

Human Immunodeficiency Virus (HIV) Leukoencephalopathy and the Microcirculation

We studied the brains of three patients with acquired immune deficiency syndrome (AIDS), all of whom developed subacutely progressive dementia unassociated with opportunistic infection or neoplasm in the central nervous system. Computed tomographic (CT) scans of the head revealed cortical atrophy, ventricular dilatation, and diffuse hypodensity of the centrum semiovale. On microscopic examination, the cerebral and cerebellar white matter in all cases showed diffuse and focal, angiocentric regions of myelin pallor, focal vacuolization, and extensive gliosis. Variable axonal loss and axonal spheroids were evident. The microvasculature showed striking changes, including mural thickening, increased cellularity, and enlargement and pleomorphism of endothelial cells with variable numbers of macrophages and multinucleated giant cells (MNGC), which often contained hemosiderin pigment. Human immunodeficiency virus type 1 (HIV-1) antigens were identified immunocytochemically within perivascular macrophages and MNGC and in some microglial cells. We suggest that the morphologic abnormalities of the microcirculation may be associated with an alteration of the blood-brain barrier. The increased vascular permeability could contribute to damage and loss of the white matter including both myelin and axons, and result in subcortical cerebral atrophy. The HIV-1 infected cells present in relation to the microvasculature may play a role in mediating the vascular injury.

A model for quantitative evaluation of embolic stroke therapy.

We developed a small animal embolic stroke model for pharmacological screening trials. Microspheres are injected into the carotid circulations and group embolus dose-response relationships are calculated. Emboli quantity is related to neurologic injury, and small changes in neurologic function are detectable. Rabbits tolerated twice as many microspheres when cyproheptadine-treated after embolization. This demonstrated both the sensitivity of the model and the value of serotonin antagonists in reducing neurological injury.

Thalamic dementia and motor neuron disease

A 46-year-old woman developed a progressive neurologic disorder over the course of 30 months which was characterized by profound dementia complicated by a motor neuron disorder that became evident 10 months prior to death. Postmortem examination of the nervous system disclosed extensive neuronal loss and gliosis of the thalamus, predominantly involving the dorsomedial nuclei, as well as severe degeneration of the corticospinal tracts, spinal anterior horns, and hypoglossal nuclei. The disease could not be transmitted to experimental animals by intracerebral inoculation of the patients brain tissue. This case represents a unique dementing disorder, possibly familial, with associated motor neuron disease.

Charcot-Marie-Tooth disease associated with hypertrophic neuropathy: a neuropathologic study of two cases.

The neuropathologic features of two cases of Charcot-Marie-Tooth disease associated with hypertrophic neuropathy are described. The peripheral nerves had a loss of myelinated fibers, endoneurial fibrosis, and numerous onion-bulb formations. The most severe changes were seen in the distal nerves. In the older of the two patients, advanced changes were also observed in the proximal nerves and anterior roots and were associated with neuronal degeneration in the anterior horns and dorsal root ganglia. The muscles were the site of chronic denervation atrophy, which was most severe in the distal portions of the lower extremities. In one of the cases, the autopsy findings were complemented by sural nerve biopsy studies, which confirmed the presence of segmental demyelination and remyelination, axonal degeneration, and Schwann cell proliferation in the form of onion bulbs. Our observations support the concept of a primary neuronal abnormality in the hypertrophic type of Charcot-Marie-Tooth disease (HN-CMT). The disorder appears to initially involve the distal axonal processes but, with progression of the disease, also involves the proximal axons, eventually leading to degeneration and loss of neurons in the anterior horns and dorsal root ganglia. Onion-bulb formation generally parallels nerve fiber degeneration, suggesting that segmental demyelination and onion bulbs may occur secondary to axonal degeneration. The possibility of a concomitant Schwann cell abnormality cannot be excluded, however, on the basis of our postmortem studies.

Perineuritis and ulcerative colitis

We describe the association of chronic polyneuropathy with ulcerative colitis. Electrophysiologic studies disclosed a severe neuropathy with both axonal and demyelinating features. The CSF protein content was 875 mg/dl. Sural nerve biopsy revealed perineuritis. Peripheral neuropathy with perineuritis may be an immunologically mediated extraintestinal manifestation of ulcerative colitis.

Spontaneous hemorrhage in a mixed glioma of the cerebellum: case report.

An 8-year-old boy presented in coma and was found to have a massive posterior fossa hemorrhage on computed tomographic scan. Autopsy disclosed a large cerebellar hematoma within a mixed glioma containing both juvenile pilocytic astrocytoma and oligodendroglioma. It is postulated that the hemorrhage originated from the oligodendroglial component of the tumor.

Congenital Choroid Plexus Papilloma of the Fourth Ventricle

A newborn infant with marked hydrocephalus had a large papilloma of the choroid plexus originating in the fourth ventricle and infiltrating the brain stem. The computed tomographic (CT) scan appearance was distinctive, showing vascularity and marked enhancement with contrast medium. Histological confirmation was made from several surgical sites. Total removal of the tumor was not possible. Review of congenital choroid plexus brain tumors reveals the location of this childs tumor in the fourth ventricle to be uncommon. (J Child Neurol 1989;4:127-130).

The indusium griseum: is it involved in Alzheimer's disease?

The histopathology of the indusium griseum (IG), a displaced hippocampal anlage, was studied in five patients with Alzheimers disease (AD) and five controls. In the AD group, the IG had occasional neurons with granulovacuolar change (GVD) and rare Hirano bodies (HB), but no senile plaques (SP), neurofibrillary tangles (NFT), or neurons staining for phosphorylated neurofilament antigen. There was a slight but not statistically significant diminution of neurons within the IG. In all AD cases, the hippocampus showed abundant AD-associated histopathology. In the control cases, only rare neurons with GVD were present in the IG. These findings indicate that although single neurons within the IG may show some of the cytologic changes seen in the hippocampal neurons in normal aging and AD, IG neurons do not express the full range and severity of histopathologic abnormalities characteristic of AD. This suggests that factors other than selective vulnerability of neurons of hippocampal origin might be operating to induce the neuropathologic picture of AD.

Motor fibers in the sural nerve.

SummaryIn an ischemia-induced model of an acute motor neuron disorder, there is anterior horn cell damage with Wallerian degeneration in ventral roots; dorsal root ganglia and dorsal roots are unaffected. In a mixed nerve there is axonal degeneration reflecting loss of motor fibers. The sural nerve is normal showing that it does not contain motor fibers. This observation is relevant to the neuropathology of motor neuron disease where axonal degeneration found in the sural nerve suggests involvement of sensory fibers.