Exploring immunoreactivity of TTF-1 and AVP in hypothalamic hamartoma.

INTRODUCTION: Hypothalamic hamartoma (HH) is a rare developmental disorder presenting with gelastic seizures or precocious puberty attributed to gonadotrophin-releasing hormone expression by the hamartoma. The histogenesis of HH is uncertain, and diagnosis of HH is difficult in small biopsies due to its close resemblance to normal hypothalamic nuclei. TTF-1 and arginine vasopressin (AVP) are associated with gonadotropin-releasing hormone release. MATERIALS AND METHODS: In this study, we explored the expression pattern of TTF-1 and AVP in HH and its utility, if any, in diagnosis. We reviewed the clinical, radiologic, and histopathological features of 23 HH diagnosed over the past decade at our Institute. RESULTS: The age at presentation ranged from 11 months to 34 years with gelastic seizures (82.6%), precocious puberty (17.4%), and developmental delay (8.7%) as presenting symptoms. On imaging, all the lesions (n = 9) involved the posterior and tuberal group of hypothalamic nuclei, while 5 cases involved the anterior hypothalamus. Anatomically, the lesions involved mammillary body, arcuate and periventricular nuclei. On histopathology, 52% cases revealed nodular arrangement of small neurocytic cells separated by glial stroma. TTF-1 and AVP immunoreactivity was absent in all the cases, whereas in normal hypothalamus, AVP was expressed in periventricular nuclei. CONCLUSION: Our results suggest that immunoexpression of TTF-1 is absent in HH, particularly in those arising from the posterior hypothalamus, and this can be used in small biopsies to distinguish from a normal hypothalamus as well as from posterior pituitary tumors.

Adult Onset Episodic Encephalopathy Due to Citrin Deficiency-A Case Report.

Hyperammonemia is a rare cause of adult episodic encephalopathy. Citrin deficiency resulting in citrullinemia type 2 (CTLN2) can lead to recurrent delirium in adults. Here we report a case of adult onset episodic encephalopathy due to citrin deficiency. A 40 years old male presented with one-year history of episodic encephalopathy triggered by high protein and fat diet. He also had chronic pancreatitis and subacute intestinal obstruction which is a novel manifestation of CTLN2. Evaluation showed elevated blood liver enzymes, ammonia, and citrulline. MRI brain showed frontal hyperintensities and bulky basal ganglia which have not been reported. Diagnosis was confirmed by next-generation sequencing which showed a novel variant c. 1591G > A in exon15 of SLC25A13. Hyperammonemic syndromes should be considered in differential diagnosis of episodic encephalopathy in adults. This report shows novel features of subacute intestinal obstruction and MRI findings in CTLN2 expanding spectrum of manifestation.

Case Report: Post-Chikungunya-Associated Myeloneuropathy.

Chikungunya virus (CHIKV) is an arbovirus endemic to South Asia with frequent outbreaks. A wide spectrum of neurological complications has been described in Chikungunya infections. Myeloneuropathy is a rare complication seen in Chikungunya and is proposed to have an underlying immune mediated pathogenesis. We report a case of a 45-year-old man presenting to the emergency services with acute onset of quadriparesis, breathlessness, urinary retention, profound pain, and sensory disturbances 6 weeks after the onset of high-grade fever and arthralgia. On examination, the patient had Medical Research Council grade 1 flaccid quadriparesis with prominent wasting and areflexia with distinct sensory level at T4. Immunoglobulin M CHIKV antibodies were positive, tested twice at a 1-week interval. He had notable magnetic resonance imaging (MRI) findings in the form of patchy T2 hyperintensities involving the entire length of the cervical and thoracic cord with normal brain imaging and extensive short tau inversion recovery hyperintense signal changes on muscle MRI. He was treated with five cycles of plasmapheresis and intravenous methylprednisolone followed by oral steroids for 8 weeks. At 20-week follow-up, the patient had improvement in upper limb weakness, but paraparesis persisted. The case highlights the presence of unusual MRI findings and also the importance of early recognition of after infective neurological complications, and prompt treatment with immunomodulation may be beneficial.

Anti-N-methyl-D-aspartate-receptor Encephalitis as a Harbinger of Pediatric HIV Infection.

Anti-N-methyl-D-aspartate-receptor (A-NMDAR) encephalitis is the most common type of autoimmune encephalitis in the pediatric age group. It is known to be triggered by viral infections such as herpes simplex infections. However, A-NMDAR encephalitis with HIV infection is a very rare event, with cases reported mostly in adults. The current report is of a previously healthy child who presented with recurrent vomiting, irritability, visual impairment, and new onset complex partial seizures and right somatosensory seizures with generalization occurring in clusters. Over a period of 3 weeks, he developed rapidly progressive bilateral painless visual loss, visual hallucinations, and behavioral changes. Brain magnetic resonance imaging (MRI) showed predominantly cortical symmetrical T2/FLAIR hyperintense signal change in parieto-occipito-temporal regions. The serum and cerebrospinal fluid were strongly positive for anti-NMDAR antibodies, and he also tested positive for HIV-1 antibodies acquired by vertical transmission. The patient and mother tested positive for HIV antibodies for the first time. Repeat MRI revealed gliosis in the parieto-occipito-temporal regions, and hippocampi showed volume loss and T2/FLAIR hyperintense signal change in the posterior thalami with patchy hyperintensities in the right putamen. The seizures subsided with immunomodulation along with anti-epileptic drugs, but he had residual cortical visual impairment on follow-up. This is the first report of A-NMDAR encephalitis presenting as a harbinger of HIV infection in a child. This calls for testing for A-NMDAR antibodies in children with HIV infection presenting with neurological or neuropsychiatric manifestations.

Altered vascular permeability but not angiogenesis may play a role in the epileptogenesis of human hippocampal sclerosis.

OBJECTIVE: We investigated the role of angiogenesis and vascular permeability in the pathogenesis of human drug-resistant epilepsy due to hippocampal sclerosis. METHODS: Resected hippocampi from 30 histologically confirmed cases of hippocampal sclerosis and 30 age-matched post-mortem controls were examined by immunohistochemical quantitation of vascular endothelial markers, CD31 and CD105 (markers of newly formed vessels), and data were analysed relative to MR volumetry. The blood-brain barrier was evaluated based on immunohistochemistry for IgG, albumin, VEGF and AQP4. RESULTS: Mean vascular density in the hippocampus was 8.71/mm2 in hippocampal sclerosis samples compared to 7.94/mm2 in age-matched controls. No statistically significant increase in vascular density was found in hippocampal sclerosis samples. Although no neoangiogenesis was found in hippocampal sclerosis samples based on CD105, breakdown of the blood-brain barrier, enhanced neuronal expression of VEGF, and perivascular seepage of IgG and albumin with uptake within neurons and astrocytes were found. Redistribution of the water channel protein, AQP4, reflected by change from normal punctate labelling to intense diffuse staining in hippocampal sclerosis samples, indicated an altered glia-vascular interface, disrupting blood-brain barrier permeability. SIGNIFICANCE: Our data show no objective histological evidence of angiogenesis in hippocampal sclerosis samples. When controlled for the confounding variable of hippocampal area, there was no difference in vascular density between cases and controls. A leaky blood-brain barrier and redistribution of AQP4 were identified which may contribute to epileptogenesis. This constitutes the largest study in the published literature evaluating a role of vascular permeability and angiogenesis in human hippocampal sclerosis.

Dual/double pathology in neurocysticercosis causing drug resistant epilepsy - Chance association or causal?

INTRODUCTION: Neurocysticercosis (NCC) as cause of drug resistant epilepsy (DRE) is commonly reported from India. We reviewed the neuropathological findings in patients undergoing resective surgery for DRE due to NCC, to determine the pathomechanism of epileptogenesis. METHODS: Clinical, demographic and neuropathological findings of histologically confirmed cases of NCC causing DRE between 2005-2019 were reviewed. NeuN, GFAP, phosphorylated neurofilament, vimentin, CD34 for glial/ neuronal alterations, and Masson trichrome, Luxol Fast blue for evidence of fibrosis/ demyelination was used to determine cause of epileptogenesis. RESULTS: There were 12 cases of NCC associated with dual/ double pathology, which constituted 3.02 % (12/398) of all the operated DRE. [Age range: 17-37y, Male:Female = 1.4:1]. Seizure duration ranged from 3-32y, with seizure onset between 4-27y. On MRI, lesions were of variable signal intensity on T1 and isointense on T2 with blooming on GRE/ SWI, and CT revealed calcification. Majority (11/12) had associated hippocampal sclerosis (HS) type 1 (dual pathology), localised to the same side as cysticercal cyst, suggesting it may be involved in the pathogenesis of HS. Ten had single cysticercal lesion involving ipsilateral hippocampus in 6, parahippocampal gyrus in 2, amygdala and temporal lobe in 1 case each. One had multiple NCC located in bilateral frontal, parietal and ipsilateral hippocampus. Adjacent cortex around the NCC evaluated in 6 cases, revealed inflammation, gliosis, axonal disruption/ beading, and variable synaptic/ neuronal dystrophic changes. There was a single case of NCC with Focal cortical dysplasia (FCD) type IIb (double pathology). In 11/12 cases Engel's post-surgery outcome was available with all having class I outcome. CONCLUSION: HS was most common pathology associated with cysticercosis (Dual pathology), localised ipsilateral to the cysticercal cyst, suggesting that HS is a secondary/ epiphenomenon. Perilesional changes such as inflammation, gliosis, dystrophic synaptic and axonal pathology play a role in inducing or perpetuating the epileptiform activity. The association of FCD IIb with NCC in one case is likely to be a chance occurrence.