Hereditary neuropathies: Genetics and utility of nerve biopsy

Peripheral neuropathy is one of the most common neurological conditions of the nervous system. Hereditary neuropathies (HNs) form an important group with varying degrees of severity, causing a significant disease burden. Accurate diagnosis is essential for management, counseling, and preventing unnecessary extended workups for acquired etiologies and inappropriate treatment. Several hereditary neuropathies have characteristic or diagnostic histologic findings; however, in the era of molecular diagnostics, the role of nerve biopsy in the diagnosis of hereditary neuropathy has reduced significantly. Nevertheless, in sporadic cases, cases without a clear family history, clinical mimics, cases with rare mutations, and genetic variants of unknown significance, a nerve biopsy can confirm the diagnosis, provide an unexpected diagnosis, or direct a targeted molecular testing. HN may be non-syndromic, affecting predominantly the peripheral nervous system or syndromic where it is a part of more widespread neurological or multisystem involvement. This review summarizes the microscopic pathological features in a nerve biopsy in some of the more commonly encountered inherited peripheral neuropathies highlighting their utility in selected cases.

Basic requirements to establish a neuromuscular laboratory

Histopathological analysis of muscle biopsy is a prerequisite in the evaluation of neuromuscular disorders, particularly inflammatory myopathies, metabolic myopathies, congenital myopathies, muscular dystrophies and differentiating myopathies and neurogenic disorders with overlapping clinically features. It not only provides useful information that helps in the diagnosis but also treatment and management. Fundamental skills and basic knowledge regarding handling, processing and analyzing a muscle biopsy are required in any specialized or a general pathology lab supporting neuromuscular clinical services. Care during transport of the muscle biopsy, sample receipt in the laboratory and grossing is very important. Standard operating procedure should be followed for the preanalytical steps (freezing and cryomicrotomy), routine and special staining (enzyme and non enzymatic) and immunohistochemistry. A well organized neuromuscular laboratory with good quality management system is necessary for the practice of myopathology. This article gives an overview of establishing such a laboratory.

Dysferlinopathy: Spectrum of pathological changes in skeletal muscle tissue.

Background: Dysferlinopathy is an autosomal recessive-limb girdle muscular dystrophy (AR-LGMD) caused due to the defect in gene encoding dysferlin, a sarcolemmal protein. Awareness of the variants and their relative frequency is essential for accurate diagnosis. Aim: To study the spectrum of morphologic changes in immunohistochemically proven cases of dysferlinopathies, to correlate the findings with clinical phenotype and durations of illness and determine the frequency. Materials and Methods: Dysferlinopathies seen over a period of 2 years at a tertiary neurological center were analyzed. Results: Clinically, majority had Miyoshi phenotype (46.6%) with distal involvement and LGMD phenotype (40%) with proximal muscle involvement. In addition, a proximo-distal and tibial muscle phenotype was encountered. Morphologically, rimmed vacuoles were noted in the Miyoshi phenotype. The presence of ragged red fibers, lobulated fibers and inflammation had no preference to a particular phenotype. Significant atrophy and lobulated fibers were noted in patients with longer duration of illness. Conclusions: Dysferlinopathy was the second most common identifiable cause (21%) of LGMD next to sarcoglycanopathies (27%).

Hemorrhagic Pericarditis in a child with primary varicella infection (chickenpox).

Chickenpox (Varicella) representing the primary infection by Varicella zoster virus is a common benign and self-limited infectious disease of childhood. Although the disease can be associated with complications, they are generally mild and tend to occur in adults and immunocompromised children. Severe and life-threatening complications are extremely rare, particularly those involving the cardiovascular system. We report a malnourished 5-year-old girl with chicken pox complicated by hemorrhagic pericarditis and deep vein thrombosis leading to fatal pulmonary thromboembolism. Though varicella infection runs a benign self-limiting course, it continues to cause significant morbidity and mortality when associated with complications, particularly in malnourished children. Hence, the importance of vaccination and early recognition of complications is emphasized.

Primary spinal paragangliomas: a clinicopathological and immunohistochemical study of six cases.

Spinal paragangliomas are uncommon neoplasms and subject of much debate regarding the factors governing their biological behaviour. We describe the clinicopathological and immunohistochemical (IHC) features of six cases of spinal paraganglioma. The mean age of patients was 40 years (range 20-60 years) with a male to female ratio of (2:1). Majority presented with low backache, sphincter disturbances and sensory symptoms. All tumors were intradural in the cauda region one of them extending to the filum. Only one showed focal extradural extension on microscopy. Gross total resection of tumors was possible in all cases. Histologically four showed classical 'zell-ballen' pattern and two revealed an ependymal morphology. On immunohistochemistry, in all the six cases the chief cells were intensely labeled by antibody to chromogranin but not for GFAP while staining for synaptophysin was less intense and variable in five. Sustentacular cells in all cases showed strong expression for S-100 protein and chief cells were stained light in three cases. Low MIB-1 labeling index of 0.01-2% was noted in five cases and in the sixth it was 5%. None of the tumours recurred. Immunohistochemistry assisted in differentiating these relatively benign neural crest tumours from the more aggressive spinal ependymomas.

Pathobiology of fungal infections of the central nervous system with special reference to the Indian scenario.

Ubiquitously present fungi in the environment find a nidus in the human body and adopt its metabolic machinery to be in symbiosis or become pathogenic. Immunocompromised states like human immunodeficiency virus (HIV) / acquired immunodeficiency syndrome (AIDS), systemic neoplasia and organ transplantation have enhanced the frequency of fungal infections. High-risk behavior, IV drug abuse and air travel have led to the emergence of new fungal infections hitherto geographically localized. The pathology in the central nervous system (CNS) is dictated largely by the size of the fungus - the yeast forms, by virtue of their small size enter the microcirculation to cause meningitis and microabscesses, while hyphal forms invade the vasculature to manifest as large pale or hemorrhagic infarcts. The growth kinetics of fungi, the antigenic character of the capsule. the proteases secreted by the mycelial forms and the biochemical milieu in the host also determine clinical manifestations. A hospital-based analysis of the available information from India suggests that in the non-HIV patient population, hyphal forms like Aspergillosis and Zygomycosis are the most common pathogens, while yeast forms like Cryptococcus and Candida are the prime pathogens in cases of HIV/AIDS, the altered macrophage function acting in synergy with suppressed cell-mediated immunity. In Northeastern states, systemic infection by Penicillium marneffei is reported in association with HIV though CNS involvement is not recorded. Although fungal infections of the CNS are reported from various hospitals in India, studies are limited by non-availability of relevant microbiological studies and the reported prevalence data is biased by the surgical practices, availability of postmortem and microbiology and laboratory support. Detailed clinical and mycological investigations related to the interaction between the fungus and host environment is a fertile area of research to understand the basic pathogenetic mechanisms.

Neuroleptospirosis - revisited: experience from a tertiary care neurological centre from south India.

BACKGROUND & OBJECTIVES: Leptospirosis is a zoonotic disease commonly reported from south India. Neurological manifestations seen in about 10-15 per cent of cases, are protean and remain unrecognized and diverse. We evaluated the pattern of nervous system involvement in leptospirosis, among patients presenting to the emergency services of a tertiary care neurological centre in south India, and also analysed the outcome and prognostic indicators. METHODS: The diagnosis of neuroleptospirosis was based on clinical and laboratory evidence of hepatorenal syndrome, and serum or CSF positivity for antileptospira antibody by a macroscopic agglutination test (MAT) and by ELISA in a limited number of samples. RESULTS: A total of 31 patients (M:F 27:4, age range 6-68 yr, mean 36.4 +/- 14.3 yr) were treated during the five year period. Acute fever with chills and rigors, headache and vomiting were the presenting manifestations; 25 patients (81%) had altered sensorium for a period ranging from 1- 8 days, four (12.9%) being deeply comatose. Eleven (35.5%) had acute symptomatic seizures at the time of presentation. Conjunctival congestion with or without haemorrhage was seen in 12 patients (38.7%), icterus in 14 (45%) and mild hepatosplenomegaly in 11 (35.5%). Early papilloedema was observed in three. Only three patients had localizing deficits. CT scan was normal in 18 of 27 (67%), while 7 (26%) had diffuse cerebral oedema. CSF pleocytosis with lymphocytic predominance (mean 50 cells/microl) and elevated protein levels (mean 115.5 +/- 67.5 mg %) were noted. Leptospira antibody was detected in serum of all, and 5 of 22 in CSF samples. Eight patients (26%) succumbed. Deep altered sensorium at presentation and raised CSF protein were two poor prognostic indicators. Pathological study of brain in five cases revealed encephalitic features and in addition immune mediated acute disseminated encephalomyelitis (ADEM) like pathology in two cases. INTERPRETATION & CONCLUSION: Neuroleptospirosis should be considered in the differential diagnosis of neuroinfections associated with hepatorenal dysfunction, in endemic areas. Leptospira antibody can be detected in CSF also in some cases. Deep altered sensorium at presentation indicates poor prognosis.

Neuropathology of HIV/AIDS with an overview of the Indian scene.

Neurological manifestations of HIV infection and AIDS are being recognized with a frequency that parallels the increasing number of AIDS cases. Next to sub-Saharan Africa, India has the second largest burden of HIV related pathology, essentially caused by HIV-1 clade C in both the geographic locales, in contrast to USA and Europe. But the true prevalence of HIV related neuroinfections and pathology is not available due to inadequate medical facilities, social stigma and ignorance that lead to underdiagnosis. Neurotuberculosis, followed by cryptococcosis and toxoplasmosis in various combinations are the major neuropathologies reflecting the endemicity and manifesting clinically by reactivation of latent infection. Discordance in the clinical prevalence of various infections, when compared to pathological studies highlight similarities in clinical, radiological modalities of diagnosis and inherent problems in establishing definitive diagnosis. Viral infections appear to be relatively rare. Inspite of heavy burden of HIV/AIDS, HIV associated neoplasia is infrequent, including primary CNS lymphomas. HIV encephalitis and HIV associated dementia are considered infrequent, though systematic studies have just been initiated in various centres. Peripheral neuropathy characteristically manifests with vasculitic neuropathy while diffuse infiltrative lymphocytosis syndrome (DILS) involving nerves has not been reported from India. Spinal cord pathology including vacuolar myelopathy is rare, even in asymptomatic cases. Till now the AIDS cases in India were drug naive but a new cohort of cases following initiation of HAART therapy as a national policy is soon emerging, altering the biology and evolution of HIV/AIDS in India. Lacunae in the epidemiology, diagnosis and study of biology of HIV/AIDS are outlined for future research.

Epithelioid and retiform hemangioendothelioma of the skull bone--report of four cases.

Hemangioendothelioma (HE) is a borderline or intermediate type of vascular neoplasm. We report clinical and histopathological characteristics of four cases of HE arising from the skull bones because of its extreme rarity in this location. The age of the patients ranged from 6-45 years. Three patients presented with a painless swelling over the head and one case had sphenoid wing mass with dimness of vision and proptosis. Radiographic images showed a well-demarcated, osteolytic lesion in the skull bone in all the four, one case in addition had sclerotic edges and another had specks of calcification. Grossly, the tumour was very vascular with hemorrhagic areas. Histologically, three cases showed features of an epithelioid variant of HE, with short strands and solid nests of rounded to slightly spindled, eosinophilic endothelial cells, some of them having small intracellular vacuoles. The stroma was myxoid--hyalinised with focal mixed inflammatory infiltrate. One case had features of a 'retiform' histological variant composed of numerous elongated vessels lined by a single layer of hobnail endothelial cells, focal lymphocytic infiltrate and papillae with hyaline collagenous cores. The tumour cells in all the four were immuno-labelled by antibody to factor VIII-associated protein. The tumour cells lacked cytological atypia and mitosis was sparse. These features were important in prognostication as low-grade tumours can be cured by complete wide-resection.

Holoprosencephaly with cyclopia--report of a pathological study.

A rare case of a lobar holoprosencephaly with cyclopia, associated with non-nervous system anomalies is being reported.

Glioneuronal migration and development disorders: histological and immunohistochemical study with a comment on evolution.

Glioneuronal migration disorders of the brain evolve primarily due to aberration in neuronal migration, maturation and programming in the development of various topographic zones in the brain, following pathological alterations in glial and neuronal interactions. These are broadly referred as cortical dysplastic conditions. While these dysplastic conditions involving cerebral cortex present as drug resistant seizure disorder, those involving cerebellum present as mass lesions or slowly progressing vertigo. We report 17 cases, representing the histological spectrum of dysplastic, glioneuronal migration disorders which include, hemimegalencephaly (1), tuberous sclerosis (4), Sturge Weber Syndrome with focal dysplasia (1), Dysembryoplastic neuroepithelial tumor (7) and Lhermitte Ductos disease of cerebellum (2). The dysplastic neurons in varied stages of maturation showed neuronal cytoskeletal pathology similar to that in neuro degenerative diseases, especially when associated with cytomegaly. Similarly, cells exhibiting dual expression of glial and neuronal markers were noted in the cerebral dysplastic lesions. The dysplastic glial elements probably form the subependymal giant cell astrocytomas. Dysplastic neuronal elements form the nidus for DNT. When localized, surgical resection ameliorate the symptoms in many of these condition. Study of these conditions provide better insight into glioneuronal interaction and maturation of the brain.

Intracranial haemorrhage resulting from unsuspected choriocarcinoma metastasis.

A retrospective analysis of clinicopathological data of 10 patients with clinically unsuspected cerebral metastatic choriocarcinoma was carried out. All patients were young adult females. History of preceding pregnancy/abortion was forthcoming in 5 cases but none had a prior history of abnormal gestation. Features of raised intracranial tension followed by hemiparesis were the commonest presenting symptoms. A clinicoradiologic diagnosis of intracerebral haemorrhagic mass, either primary or secondary to tumour bleed, cortico-venous thrombosis or arteriovenous malformation, was entertained in 8 out of 10 cases. In other two cases, ring enhancing lesions prompted the diagnosis of granulomatous masses. Eight patients were operated upon, of whom two died after short hospital stay, and were autopsied. All had haemorrhagic masses noted at surgery/autopsy. Accurate diagnosis of metastatic choriocarcinoma was established only by histologic examination of these haemorrhages. This report emphasizes the importance of considering metastatic choriocarcinoma as an important differential diagnosis of haemorrhagic intracerebral lesions in women of child bearing age group. Measurement of serum/CSF level of HCG in suspected cases helps to implement early therapy. The diagnostic value of histopathologic examination of surgically resected blood clots in determining aetiology of intracerebral haemorrhagic masses is highlighted.

Vasculitic neuropathy in HIV infection: a clinicopathological study.

Vasculitis causing peripheral neuropathy may be the first sign of HIV infection. We report four such cases in whom the onset of peripheral neuropathy led to the detection of HIV infection. Two patients presented with features of mononeuritis multiplex, while the other two had a lumbosacral polyradiculopathy. A prior history of blood transfusion was forthcoming in one of the patients. Sural nerve biopsies in all the four cases and the muscle biopsy in two, histologically showed evidence of vasculitis. Immunohistochemically, the viral antigen was not demonstrable in any of the biopsies, but on electron microscope, virus-like particles were identifiable in the Schwann cell cytoplasm and the perivascular macrophages in one case. To the best of our knowledge, this is the only report that has documented the virus in the Schwann cells as well as the perivascular macrophages lending credence to the fact that these viruses are neurotropic as well as lymphotropic. Immunoglobulin deposits were not demonstrable in any of the cases, suggesting that direct viral invasion may have a role in the pathogenesis of peripheral nerve vasculitis.

Primary angiitis of CNS : neuropathological study of three autopsied cases with brief review of literature.

Primary angiitis of CNS(PACNS) or granulomatous angiitis of CNS is a rare inflammatory disease of small blood vessels mostly confined to the CNS. The clinical and pathological features of 3 autopsied cases are described. Clinically all the three PACNS patients were young males, age ranging from 19 to 31 years. All presented with varied neurological manifestations. There was no evidence of systemic disease in any of the cases. The ESR was normal and CSF analysis showed chronic meningitic pattern. The cerebral angiogram in one case was normal and the CT scan done in another case showed multiple intracerebral haematoma due to vasculitis. Brain biopsy was not done. Diagnosis was made at post-mortem examination. Histology showed characteristic but variable degree of granulomatous and non-granulomatous angiitis of small vessels. Venulitis with parenchymal haemorrhages was the predominant feature and in one case phlebitis with thrombosis was noted. Since the disease responds to steroids and immunosuppressive therapy, establishing antemortem diagnosis is important. In view of the association of angiitis of CNS with bacteria and viral infections, their role in the evolution of the disease needs to be investigated.

Centronuclear myopathy--morphological relation to developing human skeletal muscle: a clinicopathological evaluation.

Centronuclear myopathy (CNM), an uncommon condition, is one of the congenital myopathies. It is believed to arise as a result of maturational arrest, with persistence of myotubes postnatally. However, denervation being the basic disease process and its possible influence on central nervous system causing defect in nuclear migration has also been postulated. Keeping in view these existing controversies, we have studied 17 cases of CNM (neonatal - 1, childhood - 13, adulthood - 3) during the last twelve and a half years. Diagnosis was based on histological and enzyme histochemical findings of muscle biopsy along with clinical data. Ultrastructural characterstics of muscle have been studied in 10 cases. The affected muscle fibres showed a central nucleus (40-99%) with perinuclear halo. Type I fibre predominance with hypoplasia was consistently seen. Fibre type disproportion was noticed in 7 cases. The neonatal form revealed dense oxidative enzyme reaction product in the centre. The morphological features of CNM were compared with foetal skeletal muscles obtained at gestational ages ranging from 9 weeks - 36 weeks (n = 18). In the severe neonatal form th myofibres resembled the foetal myotubes. In the less severe childhood and adult form of CNM, aberrant organization of cytoskeletal network might have played a pathogenetic role in causing the disease.

Histopathological & immunohistochemical evaluation of ageing changes in normal human brain.

As age related changes in the brain have not been systematically studied in the Indian population though there is an impression that they are less frequent, we studied 52 brains collected at autopsy from individuals above the age of 60 yr. The incidence of senile plaques (SPs) and neurofibrillary tangles (NFTs) together were found to increase with age from 21 per cent in the seventh decade to 33 per cent in the eighth decade and 54 per cent in the ninth decade, the increasing incidence of NFTs being statistically significant. The SPs were found both in the hippocampus and frontal cortex while NFTs were seen only in the hippocampus in non-demented aged individuals. In contrast, in the three cases of Alzheimer's disease (symbol: see text) AD studied, the NFTs and SPs were found in high density in both hippocampus and frontal cortex. By immunohistochemistry, various morphological forms of SPs were found to have beta amyloid protein consistently, while ubiquitin and phosphorylated neurofilament occurred variably. More number of SPs could be labelled by amyloid immunostaining than by conventional silver stains. The NFTs contained ubiquitin and phosphorylated neurofilament protein as the antigenic components, both in AD and normal ageing. The incidence of age related changes and their antigenic character in the limited sample studied from south India appears to be comparable to findings from the West. Multicentric studies on a large sample derived from different ethnic groups in India are needed to further evaluate these features.