Synapses in the hereditary ataxias.

The goal of this investigation was the systematic assessment of synapses in the hereditary ataxias by the immunocytochemical and immunofluorescent visualization of SNAP-25, a protein of the presynaptic membrane. Sections were prepared from the cerebellar cortex, dentate nucleus, basis pontis, inferior olivary nuclei, and the spinal cord in 57 cases of autosomal dominant and recessive ataxia. The neuropathological phenotype included 18 cases of olivopontocerebellar atrophy (OPCA), 14 cases of familial cortical cerebellar atrophy (FCCA), 4 cases of Machado-Joseph disease (MJD), and 21 cases of Friedreich's ataxia (FA). Among the autosomal dominant ataxias, spinocerebellar ataxia type 1 (SCA-1), SCA-2, MJD/SCA-3, and SCA-6 were represented. Expanded guanine-adenine-adenine trinucleotide repeats were confirmed in 7 patients with FA. The abundance of SNAP-25 was estimated by comparing the fluorescence of the regions of interest to that of the frontal cortex, which was considered unaffected by the disease process. Despite severe Purkinje cell loss, abundant SNAP-25 reaction product remained in the molecular layer of FCCA and OPCA. Among the cases of OPCA, those identified as SCA-2 showed the most severe overall synaptic destruction in cerebellum and brain stem. In SCA-1, which caused either OPCA or FCCA, significant synaptic loss was restricted to the inferior olivary nuclei. Sparing of cerebellar cortex and inferior olivary nuclei was the rule for MJD/SCA-3 and FA, though the dentate nucleus showed reduced SNAP-25 immunoreactivity in both ataxias. In FA, preservation of SNAP-25 in the dentate nucleus was characteristic of long survival. Severe cases with short survival revealed synaptic depletion of the dentate nucleus. At the level of the spinal cord, synaptic loss in the dorsal nuclei of Clarke characterized FA and MJD/SCA-3. The inexorable clinical progression of the hereditary ataxias could not be attributed to synaptic loss in a single anatomic structure of cerebellum, brain stem, or spinal cord. Nevertheless, synaptic loss in dentate and inferior olivary nuclei correlated more precisely with the severity of the ataxia than the changes in the cerebellar cortex.

Somatic mosaicism for Friedreich's ataxia GAA triplet repeat expansions in the central nervous system.

Most patients with Friedreich's ataxia (FRDA) carry expanded GAA repeats in both homologues of the frataxin gene on chromosome 9. We determined the size of the GAA repeats in autopsied samples from the CNS of six FRDA patients. We observed heterogeneity of repeat sizes in different CNS regions, indicative of extensive mitotic instability. Samples from the same CNS subdivision (e.g., cortex, thalamus) contained a similar mixture of alleles, suggesting that the pattern of repeat size mosaicism reflects the developmental history of each sample. Regional differences in repeat size could not account for the characteristic distribution of pathology in FRDA, which appears instead to be related to the pattern of frataxin expression.

Long-standing goiter and hypothyroidism: an unusual presentation of a TSH-secreting adenoma.

A 63-year-old female patient was referred to our hospital in February 1994 for a pituitary tumor. On a previous examination, in 1973, she had a goiter, nonspecific symptoms and only an elevated serum T3. In 1984 she had become hypothyroid, her goiter had increased, serum T4 was 69 nmol/L, TSH 34.4 mU/L, and TPO antibodies were positive. Hypothyroidism due to autoimmune thyroiditis was diagnosed and she received L-T4 100 micrograms/day. In 1985 and 1986, serum TSH had decreased but remained slightly elevated, while T4 was at the upper limits of normal. From 1987 to 1989 her serum TSH rose from 9 to 20 mU/L and remained at that level for the ensuing 4 years in spite of increasing L-T4 up to 150 micrograms/day. In October 1993, after discontinuing L-T4 for 6 weeks, TSH was 23.7 mU/L, T4 170 nmol/L, 131I thyroid uptake 52%, and the CT scan showed a large pituitary tumor with suprasellar extension. On preoperative investigation TSH was 40-51 mU/L with no response to TRH or GnRH. The alpha-subunit was increased at 6.33 micrograms/L with the alpha-TSH/TSH molar ratio of 1.23. Prolactin was elevated, but plasma cortisol, FSH, and LH were low. At surgery, we found a large chromophobe adenoma with few PAS-positive granules and with immunostaining positive for TSH and prolactin. From the clinical and biological data, we can conclude that the patient had probably a TSH-secreting adenoma since the goiter was first detected. The development, however, of autoimmune thyroiditis with hypothyroidism considerably modified the presentation of the disease and may have accelerated the growth of the tumor.

Primary post-traumatic intraorbital meningioma.

Intraorbital meningiomas are uncommon tumours that usually represent extension from a primary intracranial tumour. Trauma has been proposed by Cushing and Eisenhardt as an etiologic factor in the development of meningioma following head injury. We report a case of primary post-traumatic intraorbital meningioma and discuss its pathogenesis and management.

Paraneoplastic encephalomyelitis and subacute dysautonomia due to an occult atypical carcinoid tumour of the lung.

A case of paraneoplastic encephalomyelitis and subacute pandysautonomia associated with an occult atypical carcinoid tumour of the lung is described. The main clinical features were lethargy, impaired memory, constipation, and orthostatic hypotension. Neurological investigation was unremarkable except for mononuclear pleocytosis and increased protein level in the cerebrospinal fluid (CSF). Tests of autonomic function revealed a low plasma norepinephrine level, a marked drop of blood pressure (BP) to vertical tilt and Valsalva maneuver, and a marked rise of BP to dilute norepinephrine infusion. A few days prior to death, the patient became hypothermic and had repeated episodes of respiratory arrest associated with transient atrioventricular block on the electrocardiogram (ECG). A polysomnographic study confirmed a sleep apnea syndrome. Autopsy revealed an atypical carcinoid tumour in one tracheobronchial lymph node, widespread lymphocytic infiltrates and loss of neurons in the cerebral, cerebellar and brainstem grey matter, the spinal cord and roots, and the paravertebral sympathetic ganglia as well as microglial and astrocytic proliferation in the central nervous system.

Cystic schwannoma of the brainstem.

A rare case of cystic schwannoma occurring in the brainstem in the absence of von Recklinghausen's disease is reported. This appears to be the first case in the literature of a cystic schwannoma ever described in this location. While the exact origin of this tumor in this unusual location remains uncertain, different hypotheses are discussed and the possible origin of this tumor from perivascular elements in the brainstem is seriously considered.

The neuropathology of "typical" Friedreich's ataxia in Quebec.

We present the pathological data from the autopsies performed on 6 Friedreich's disease patients since the start of the Quebec Cooperative Study. All patients met the strict diagnostic criteria of the QCSFA. The anatomical lesions found in the peripheral and central nervous system were similar in all 6 cases and do not differ from those described in the literature. The clinical findings correlate closely with the histological lesions found in the peripheral nervous system and spinal cord. The evidence of segmental demyelination and remyelination in the spinal ganglia and posterior roots further supports the dying-back axonopathy hypothesis.

Spinal cord paralysis following sclerotherapy for esophageal varices.

A child with cryptogenic cirrhosis underwent a third session of elective sclerotherapy. Endoscopic therapy consisted of intravascular injection of ethanolamine oleate in varices newly developed at the midesophagus level. Irreversible paraplegia was documented within 8 hr postoperatively. Two years later she eventually died from gastrointestinal bleeding. Autopsy findings were compatible with an infarct of the spinal cord secondary to an occlusion of the anterior spinal artery. Various hypotheses which might explain the passage of the sclerosing material from the esophagus to the anterior spinal artery include: arterial occlusion secondary to venous thrombosis and spinal cord necrosis, accidental injection in an intercostal artery or azygous vein through the esophageal wall, the presence of a congenital arteriovenous fistula or the opening of arteriovenous shunt. Paravasal injection of dilute sclerosing agent might protect against this unusual but dramatic complication.

The cardiomyopathy of Friedreich's ataxia morphological observations in 3 cases.

In the light of the recent finding of deposits of calcium salts and iron in myocardial cells in one case of Friedreich's ataxia, we have made a detailed morphological study of 3 new cases of this cardiomyopathy. Calcium deposits were not found in the muscle fibers but lipofuscin granules and deposits of iron were observed in our 3 cases. In addition to the usual findings of interstitial fibrosis, hypertrophy and degeneration of myocardial fibers, foci of segmental active muscle necrosis were constantly present. There is a possibility that Friedreich's ataxia could be a neurocardiac degenerative disease with a membrane defect which could be related to defective metabolism of vitamin E or other micronutrients.