S. K. Shankar

Anti-brain autoantibodies and altered excitatory neurotransmitters in obsessive-compulsive disorder.

Although serum autoantibodies directed against basal ganglia (BG) implicate autoimmunity in the pathogenesis of obsessive–compulsive disorder (OCD), it is unclear whether these antibodies can cross the blood–brain barrier to bind against BG or other components of the OCD circuit. It is also unclear how they might lead to hyperactivity in the OCD circuit. We examined this by investigating the presence of autoantibodies directed against the BG or thalamus in the serum as well as CSF of 23 OCD patients compared with 23 matched psychiatrically normal controls using western blot. We further investigated CSF amino acid (glutamate, GABA, taurine, and glycine) levels and also examined the extent to which these levels were related to the presence of autoantibodies. There was evidence of significantly more binding of CSF autoantibodies to homogenate of BG as well as to homogenate of thalamus among OCD patients compared with controls. There was no significant difference in binding between patient and control sera except for a trend toward more bands to BG and thalamic protein corresponding to 43 kD among OCD patients compared with controls. CSF glutamate and glycine levels were also significantly higher in OCD patients compared with controls, and further multivariate analysis of variance showed that CSF glycine levels were higher in those OCD patients who had autoantibodies compared with those without. The results of our study implicate autoimmune mechanisms in the pathogenesis of OCD and also provide preliminary evidence that autoantibodies against BG and thalamus may cause OCD by modulating excitatory neurotransmission.

Cryptococcal meningitis: Clinical, diagnostic and therapeutic overviews

Cryptococcal meningitis has emerged as a leading cause of infectious morbidity and mortality in patients with AIDS. Among the human immunodeficiency virus (HIV)-seropositive subjects, cryptococcal meningitis is the second most common cause of opportunistic neuro-infection. Current trends are changing due to the marked improvement of quality and length of life produced by highly active antiretroviral therapy (HAART). The introduction of generic HAART in India has resulted in an increase in the number of individuals getting treatment for HIV infection, as the cost of highly active antiretroviral therapy (HAART) has decreased 20- fold. Cryptococcal meningitis occurs in non-HIV patients who are immunodeficient due to diabetes, cancer, solid organ transplants, chemotherapeutic drugs, hematological malignancies etc and rarely in healthy individuals with no obvious predisposing factors. Diagnosis of cryptococcal meningitis is fairly straightforward once the diagnosis is considered in the differential diagnosis of chronic meningitis. Treatment of a patient with cryptococcal infection is a challenge for both the physician and the patient, but rewarding, as many would recover with timely and adequate antifungal therapy.

Biology of aging brain.

Normal aging of the nervous system is associated with some degree of decline in a number of cognitive functions. With the present day attempts to increase the life span, understanding the metabolic interactions and various mechanisms involved in normal neuronal aging continues to be a challenge. Loss of neurons is now recognized to be more modest than the initial estimates suggested and the loss only affected some of the specific neuroanatomical areas like hippocampus and prefrontal cortex. Individual neurons in addition show reduced size of dendritic and axonal arborization. Neurons have significant homeostatic control of the essential physiological functions like synaptic excitability, gene expression and metabolic regulation. Deviation in these normal events can have severe consequences as observed in aging and neurodegeneration. Based on experimental evidence, the evolution of aging is probably the result of altered metabolic triad: the mitochondria, reactive oxygen species and intracellular calcium homeostasis. Perturbations in the metabolic and functional state of this triad lead to a state of decreased homeostatic reserve, where the aged neurons still could maintain adequate function during normal activity. However, these neurons become vulnerable to the stress of excessive metabolic loads associated with spells of ischemia, trauma progressing to neuronal degeneration. Age-related neuronal dysfunction probably involves a host of subtle changes involving the synapses, receptors, neurotransmitters, cytological alterations, electrical transmission, leading to cognitive dysfunction. An exaggeration of it could be the clinical manifestation of dementia, with intraneuronal accumulation of protein aggregates deranging the metabolic state. This review deals with some of the structural, functional and metabolic features of aging nervous system and discusses briefly the functional consequences.

Eccentric Target Sign in Cerebral Toxoplasmosis – neuropathological correlate to the imaging feature

Cerebral toxoplasmosis remains one of the most common focal brain lesions in patients with acquired immune deficiency syndrome (AIDS). Diagnosis is a challenge because on cranial imaging it closely mimics central nervous system lymphoma, primary and metastatic central nervous system (CNS) tumors, or other intracranial infections like tuberculoma or abscesses. A magnetic resonance imaging (MRI) feature on postcontrast T1‐weighted sequences considered pathognomonic of toxoplasmosis is the “eccentric target sign.” The pathological correlate of this imaging sign has been speculative. Herein we correlate the underlying histopathology to the MR feature of eccentric target sign in a patient with autopsy‐proven HIV/AIDS‐related cerebral toxoplasmosis. The central enhancing core of the target seen on MRI was produced by a leash of inflamed vessels extending down the length of the sulcus that was surrounded by concentric zones of necrosis and a wall composed of histiocytes and proliferating blood vessels, with impaired permeability producing the peripheral enhancing rim. J. Magn. Reson. Imaging 2010;31:1469–1472.

Low prevalence of progressive multifocal leukoencephalopathy in India and Africa: Is there a biological explanation?

Infection with human immunodeficiency virus (HIV) clade C virus is the most common form of HIV infection in the world. It largely infects populations in Africa and Asia and not much is known about the neurological complications associated with the virus. Cases of progressive multifocal leukoencephalopathy (PML) have been rarely reported in the literature in the acquired immunodeficiency syndrome (AIDS) or non-AIDS populations from these regions. In this article, the authors present three recently diagnosed patients with AIDS and PML from one neurological center in India, review the diagnostic challenges faced, and speculate on the possible biological reasons, including viral strain differences as well as HIV and JC virus interactions, that may account for the low incidence.

Subependymal giant cell astrocytoma: a clinicopathological study of 23 cases with special emphasis on proliferative markers and expression of p53 and retinoblastoma gene proteins

Aims: To gain a better insight into the biological behaviour of subependymal giant cell astrocytoma (SEGA), tumour suppressor gene protein expression and various proliferative indices were studied in these tumours and correlated with histological features and clinical outcome. Methods: We studied 23 cases of SEGA, 19 from our own Institute and four from the National Institute of Mental Health and Neurological Sciences (NIMHANS), Bangalore, India. Immunohistochemical staining for various glial and neuronal markers, proliferative markers (MIB‐1, Topoisomerase II α PCNA) and tumour suppressor gene protein expression of p53 and retinoblastoma (Rb) were performed. Results: Nineteen cases of SEGA were collected over a period of 23 years (January 1978–December 2001), which accounted for 0.16% of all intracranial tumours and 0.51% of all gliomas reported at this centre. Ages ranged from 4 to 37 years (mean 13.2 years) with a male preponderance. Nine of the 23 cases were associated with tuberous sclerosis (TS), six at the time of diagnosis, while three developed TS during the follow‐up period. Treatment consisted of surgical resection (total in nine cases and subtotal in 14 cases) followed by radiotherapy in seven cases. Except for two patients who died in the immediate post‐operative period of surgical complications, the remaining patients were all alive in the follow‐up period (mean 37.1 months). One patient experienced recurrence 22 years after the first surgery and a second patient after 2 years. Necrosis and/or mitoses were observed in five cases. Immunohistochemically, tumours were positive for both glial and neuronal markers. Interspersed inflammatory cells were a mixture of mast cells and lymphocytes of T immunophenotype. The MIB‐1 labelling index (LI) ranged from 0 to 8% (mean 3.0%), topoisomerase II α (topo II α) LI from 0 to 9.5% (mean 2.9%) and PCNA LI from 10 to 59% (mean 32.5%). The difference in the labelling indices of tumours with and without mitoses and/or necrosis was not statistically significant. None of the tumours revealed loss of Rb gene protein expression. p53 immunopositivity was seen in 14 cases (labelling indices ranged from 1 to 7.3% with a mean of 2.4%). The correlation between the MIB‐1 LI and topo II α LI, and topo II α LI and PCNA LI was significant (P<0.05) but not so with other parameters like p53 protein expression, duration of survival and morphological features such as mitoses and necrosis. Conclusions: SEGAs are rare intraventricular tumours associated with TS and express both neuronal and glial markers. They have a low proliferative potential. Mitoses and necrosis are not associated with a worse prognosis. In view of the low proliferative indices and long survival of these patients without recurrence, the role of post‐operative radiotherapy is questionable. These patients should be followed up closely as many of them develop stigmata of tuberous sclerosis at a later stage.

Rabies viral encephalitis: clinical determinants in diagnosis with special reference to paralytic form

Background Rabies is an important public health problem in developing countries such as India where an alarmingly high incidence of the infection is reported every year despite the availability of highly effective, potent and safe vaccines. In clinical practice, diagnosis of the furious (encephalitic) form of rabies poses little difficulty. In contrast, the paralytic form poses a diagnostic dilemma, to distinguish it from Guillain–Barré syndrome. The problem is further compounded in the absence of a history of dog bite, clinical features resembling a psychiatric syndrome. Method The present study analysed the spectrum of neurological manifestations in 47 cases of rabies encephalitis (34 paralytic, six encephalitic, and seven psychiatric manifestations) from two hospitals in south India, confirmed at post-mortem by demonstration of a viral antigen in the brain. A history of dog bite was elicited in 33 patients and fox bite in one. Twenty-two patients received postexposure prophylaxis. The incubation period ranged from 7 days to 4 years. Clinical features were analysed, looking for any clinical pointers that provide clues to a diagnosis of paralytic rabies. Results and discussion Fever, distal paresthaesias, fasciculation, alteration in sensorium, rapid progression of symptoms and pleocytosis in cerebrospinal fluid should alert the neurologist to consider rabies encephalomyelitis. Detection of the viral antigen in the corneal smear and a skin biopsy from the nape of the neck had limited usefulness in the ante-mortem diagnosis. Although a few clinical signs may help indicate rabies encephalomyelitis antemortem, confirmation requires neuropathological/neurovirological assistance. The preponderance of atypical/paralytic cases in this series suggests that neurologists and psychiatrists need to have a high index of clinical suspicion, particularly in the absence of a history of dog bite.

Desmoplastic infantile ganglioglioma - clinicopathological and immunohistochemical study of four cases

Abstract Case reports. Four cases of desmoplastic infantile ganglioglioma (DIG) seen in India are described. These patients presented with large, supratentorial, superficially situated cystic tumours that showed glial and ganglionic differentiation; accompanied by a severe desmoplastic reaction. MIB-1 labelling was rare, despite foci of apparently primitive neuroepithelial cells. There was lacking p53 protein expression by tumour cells in all cases. The prognosis was good following either partial or complete tumour resection. DIGs are a distinct form of developmental neuroepithelial tumour, probably arising from neural progenitor cells in subcortical zone along with mature subpial astrocytes. Conclusions. In view of its favourable prognosis, this tumour has to be diagnosed accurately by immunohistochemical techniques using glial and neuronal markers. The absence of p53 protein expression suggests that DIG probably has different molecular genetic pathways from other supratentorial astrocytomas.

Spectrum of epilepsy in Wilson's disease with electroencephalographic, MR imaging and pathological correlates

BACKGROUND Seizures are uncommon in Wilsons disease. OBJECTIVE To analyze profile of seizures in WD and to correlate with EEG and MR imaging observations. SUBJECTS AND METHODS 41/490 patients (8.3%) of WD were documented to have seizures. Autopsy observations were available in 3 cases. RESULTS The age at onset of seizures was 12.8+/-5.7years. Seizure - preceded the onset of characteristic features of WD (19.5%); occurred concurrently (46.3%); or, followed de-coppering therapy (29.2%) and occurred as terminal event (4.8%). The types of seizures were: generalized tonic-clonic - 29, simple partial - 8, complex partial - 6, partial seizures with secondary generalization - 2 and periodic myoclonus - 1. Six patients had multiple seizure types and 4 had status epilepticus. EEG abnormalities were frequent (19/24) consisting of background slowing and epileptiform discharges. MRI (n=20) revealed varying degree of atrophy and signal changes involving basal ganglia, brainstem and white matter. The duration of follow-up was 8.1+/-9.2years. The outcome of seizure was: no recurrence - 68.3%, breakthrough seizures - 17.1%, poor control - 9.7% and no follow-up - 4.9%. Two of them succumbed following cluster attacks. Autopsy revealed cavitatory lesions in white matter in frontal, temporal and parietal areas with varying involvement of cortical ribbon. Patients with seizures had more often white matter changes than those without. It was also noted that patients whose seizures were not controlled had MRI suggestive of cavitation of white matter, though the reverse was not true. CONCLUSIONS This is the largest series regarding epilepsy in WD. Seizures are not uncommon and could occur at any stage. Deafferentation of white matter tracts from cortex may contribute for seizure in WD.

Apolipoprotein E polymorphism and outcome after mild to moderate traumatic brain injury: A study of patient population in India

BACKGROUND The nature and extent of recovery after traumatic brain injury (TBI) is heterogeneous. Apolipoprotein E (APOE) plays a major role in repair of cell membrane and growth of neurites following injury to cells. Studies done on the western population have shown that the APOE e4 genotype is associated with poor survival following neurotrauma. AIM To explore the association of APOE polymorphism and outcome following TBI in a patient population from a tertiary care hospital exclusive for neurological diseases in south India. PATIENTS AND METHODS Ninety eight patients who sustained mild to moderate TBI (computed tomography (CT) scan brain showing traumatic parenchymal contusions) were the subjects of the study and the study period was from November 2003 to December 2008. APOE polymorphism status was determined by PCR technique using venous blood. Patients were assessed on follow-up with a battery of four neuropsychological tests as well as Glasgow outcome scale. RESULTS Of the 98 patients, 20 (20%) patients had at least one APOE e4 allele. A follow-up of minimum six months was available for 73 patients. None of the 12 patients who had at least one APOE e4 allele had a poor outcome at six-month follow-up whereas 11(18%) patients without an APOE e4 allele had a poor outcome (Fishers Exact test, P=0.192). On the neuropsychological tests, performance of patients with APOE e4 allele did not differ significantly from those without these alleles. CONCLUSION This study does not support the current contention that the presence of APOE e4 allele should have a significant negative effect on the outcome after TBI.