[Chronic sciatic pain caused by sciatic nerve schwannoma]. / Sciatalgie chronique révélant un schwannome du nerf sciatique.

Schwannomas are tumors with slowly progressive symptoms, more often painful than associated with neurologic deficits. Involvement of the sciatic nerve mimics chronic sciatic pain due to a herniated disk. If there is no lumbar pain and lumbar MRI is normal, the sciatic nerve must be clinically and radiologically examined all along its course. We report a patient with chronic sciatica in whom physical examination revealed a painful mass with a Tinel sign in her back thigh. MRI showed a multilobular mass along the sciatic nerve. Surgery of this plexiform schwannoma allowed a complete relief from pain.

[Miliary cerebral Histoplasma capsulatum in an HIV-negative patient]. / Miliaire cérébrale à Histoplasma capsulatum chez un patient séro-négatif pour le VIH.

A 58 year-old man who lived in Africa for 17 years, presented, four years after returning to western France, acute confusion and weight loss. He had no fever and no immunosuppression. Clinical examination revealed Babinski sign, mucosal ulcerations of the mouth and hepatomegaly. The lumbar puncture revealed a meningitis and MRI showed a few parenchymal enhancing masses in the brain. Stereotaxic biopsies were performed. Specific culture and coloration were positive for the diagnosis of cerebral histoplasmosis. At the beginning, antifungal treatment with amphotericin B and itraconazole provided improvement. But seizures occurred and the treatment by carbamazepine induced decreased blood level of itraconazole. Despite itraconazole IV the patient died. This observation illustrates the difficulties in diagnosis and treatment of cerebral histoplasmosis and the various patterns of drug interactions.

Perioperative lumbar injection of Ringer's lactate solution in chronic subdural hematomas: a series of 100 cases.

A series of 100 patients underwent surgical treatment for chronic subdural hematomas between 1979 and 1987. The procedure consisted of craniectomy with a 30-mm trephine, irrigation and drainage of the hematoma, laceration of the outer and inner membranes, and lumbar intrathecal injection of Ringer's lactate solution for immediate cerebral reexpansion (average injection, 130 ml). This technique gave the following results: 2% mortality, 2% moderate morbidity, and 96% recovery. The recovery of the patients was rapid, and good outcome was achieved in Grade 3 and Grade 4 cases (Markwalder's classification).

[Hemichorea and striatal infarction]. / Hémichorée et infarctus striatal.

We present two cases of hemichorea associated with an arterial ischaemic stroke in the controlateral striatum and we reviewed 28 similar cases in the literature. The pathogenesis of this movement disorder involves the gabaergic and enkephalinergic neurons of the striatal matrice which mainly projects on the external globus pallidus. A destruction of the striatal neurons of the indirect striato-thalamo-cortical ways may reduce their inhibitory out flow on normal inhibited thalamic and cortical structures and then create abnormal choreiform movements. The scarcity of this phenomenon can be explained by: 1) the repartition of the enkephalinergic local circuit neurons which represent but one third of the motor striatal neuronal population; 2) the type of vascularisation which often involves larger territories in the striatum and the globus pallidus or the anterior limb of the internal capsule. These abnormal movements are often transient because of the regulation of accessory striato-nigro-striatal, cortico-striato-nigro-thalamo-cortical and cortico-luysin circuits. More over, because these hypotheses and after having reviewed all such cases in literature, choreic movements to pure thalamic involvement are to be questioned.

[Clinical, electrophysiological and MRI correlations in carpal tunnel syndrome]. / Etude des corrélations cliniques, électrophysiologiques et IRM dans le syndrome du canal carpien.

UNLABELLED: Even though diagnosis of carpal tunnel syndrome is mainly based on clinical findings, other examinations are often useful for confirmation and management. The most useful of these examinations is EMG. However, EMG may be inconclusive and MRI may then be helpful. The indications for MRI in patients with carpal tunnel syndrome will be reviewed. METHOD: 20 patients with a total of 33 clinically suspected cases of carpal tunnel syndrome (CTS) underwent EMG and MRI evaluation. Clinical and EMG findings identified three groups of patients based on degree of deficit: mild, moderate, and severe. The following structures were evaluated at MRI: median nerve, retinaculum, retrotendinous fat, flexor tendons, thenar space, and muscles and bones of the wrist. Surgery was performed for 19 wrists. RESULTS: Only retinacular bowing and increased T2W signal intensity within the median nerve were significantly related to the diagnosis of CTS (sensitivity of 70% and 57% respectively). Retinacular bowing indicates increased "pressure" within the compartment (mechanical compression of the nerve) and increased T2W signal of the median nerve indicates nerve suffering. These findings correlated well with more severe cases based on clinical and EMG findings. CONCLUSION: In cases where there is discordance between clinical and EMG findings, MRI is helpful to identify patients who would benefit from surgical intervention.

[Hydrocephalus and cerebral cysticercosis. A case report. Review of the literature]. / Hydrocéphalie et cysticercose cérébrale. A propos d'un cas. Revue de la littérature.

A case of intraventricular and cisternal cerebral cysticercosis with no intraparenchymatous involvement is reported. The clinical features were characterized by episodes of blockage of the C.S.F. pathways producing acute hydrocephalus. On three occasions surgical treatment was required: two ventriculoperitoneal shunts and a ventriculocisternostomy were performed. The intraventricular cystic membranes found during the third operation suggested the diagnosis. Epidemiological arguments, the pathogenesis of hydrocephalus and diagnostic and therapeutic aspects are discussed in the light of the literature data.

[Extra-medullary intradural melanotic tumor: apropos of a case of dorsal pigmented neurinoma. Review of the literature]. / Tumeur mélanique intradurale extramédullaire: a propos d'un cas de neurinome pigmenté dorsal. Revue de la littérature.

The authors report a case of pigmented thoracic neuroma (T3) discovered in a 40 year old woman on a routine chest x-ray. This hourglass-shaped extra-dural tumour was investigated by computed tomography, nuclear magnetic resonance imaging and iopamiron myelography. Treatment consisted of complete resection by T2-T3 laminectomy and left T3 foraminotomy. Light and electron microscopy revealed melanin secretion by the Schwann cells. A review of the literature confirms the findings observed in our case in terms of the slow clinical course, the benign nature and the excellent prognosis following complete resection, without the need for any radiotherapy or chemotherapy. The various histogenetic theories of extramedullary intra-dural melanotic tumours are reviewed. The difficulties of the differential diagnosis are discussed.

Effects of high pressure on nervous conduction velocity in man.

The velocities of motor and sensory nervous conduction and of neuro-muscular transmission were measured in four subjects during a simulated dive at 4.6 MPa (46 bars). The results show an increase in motor distal latency in the ulnar nerve, especially during decompression, with reversibility of the effect on return to ambient conditions. The hypothesis of an interaction of dissolved gases with the membranes of ischaemic cells is proposed.

Proton nuclear Overhauser effect study of the structure of a deoxyoligonucleotide duplex in aqueous solution.

Nuclear Overhauser enhancements (NOEs) have been observed between some of the nonexchangeable protons of the self-complementary octanucleoside heptaphosphate d(G-G-T-A-T-A-C-C) in conditions under which duplex formation takes place. Comparison of inter- and intraresidue NOEs has made possible the assignment of all the aromatic and 1'- and 2'-ribosyl signals. In particular, and with the exception of the 5' terminal, NOEs of comparable magnitude are observed between H-8 of purines or H-6 of pyrimidines and pairs of anomeric protons. There are the H-1's of the nucleotide containing the relevant aromatic proton and those of the adjacent residue in the 5' direction. Differentially evolving NOEs are also generated between aromatic protons and the C-2' methylene protons on both the same residue and on the neighboring 5' residue. The relative magnitudes of these NOEs are discussed in terms of overall helical geometry and are consistent with a generally accepted B-type DNA model (R. Chandrasekaran and S. Arnott, personal communications).

Idiopathic carpal tunnel syndrome. Clinical, electrodiagnostic, and magnetic resonance imaging correlations.

BACKGROUND: Although carpal tunnel syndrome is diagnosed primarily on clinical grounds, a number of investigations can be helpful in confirming the diagnosis and providing therapeutic orientation. Electrodiagnostic testing is the most widely used method in everyday practice but can be inconclusive or inconsistent with the clinical findings. Magnetic resonance imaging is useful in such cases. OBJECTIVES: To compare the diagnostic usefulness of electrodiagnostic testing and magnetic resonance imaging in patients with carpal tunnel syndrome. PATIENTS AND METHODS: Thirty-three cases of clinically-defined carpal tunnel syndrome in 20 patients were investigated by electrodiagnostic testing and magnetic resonance imaging. The nerve entrapment was categorized as mild, moderate, or severe based on clinical and electrodiagnostic findings. Structures evaluated on magnetic resonance imaging scans were the median nerve, the flexor retinaculum, the flexor tendons, the fat lying deep to the tendons, the thenar compartment, and the carpal bones. RESULTS: Bowing of the transverse carpal ligament, high signal from the median nerve on T2 images, and median nerve enlargement were found in 70%, 57%, and 55% of cases, respectively. Bowing of the transverse carpal ligament is a cause of mechanical compression, whereas the other two signs reflect injury to the median nerve. High signal from the median nerve was associated with more severe clinical and/or electrodiagnostic abnormalities. CONCLUSION: When electrodiagnostic abnormalities suggest more severe disease than expected or are otherwise discordant with clinical findings, demonstration by magnetic resonance imaging of high median nerve signal and/or median nerve enlargement may help to select those patients most likely to benefit from surgical treatment.