Rev Neurol France
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The authors report the clinical signs and histological findings in 62 patients with ocular myopathies divided into two groups: (a) ocular myopathies with mitochondrial abnormalities, themselves divided into pure (19 cases) or progressive (15 cases) ophthalmoplegia, and multisystemic myopathies (14 cases); (2) oculopharyngeal myopathies (15 cases) in elderly subjects, with constant intranuclear tubulofilamentous inclusions. Among myopathies with mitochondrial abnormalities, ocular forms with a favourable prognosis coexisted with earlier and more severe multisystemic lesions.
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Heat stimuli, applied to the skin by non-contact radiation pulses emitted by a CO2-laser, activate simultaneously both A-delta (mean conduction velocity 14 m/s) and C-fibres (0.8 m/s), which terminate in the most superficial skin layers. Correspondingly, brief heat stimuli elicit two pain sensations with mean reaction times of about 500 ms and 1400 ms. Similarly, two evoked potential waveforms were observed in the electroencephalogram: the late components N240/P370 and the ultralate components N1050/P1250. ⋯ In cases with hereditary motor and sensory neuropathy type I or with neurosyphilis, ultralate potentials are observed as correlates of delayed pain perception in the affected body areas. The laser evoked cerebral potentials reflected the clinical disorder of pain sensitivity in most cases, whereas somatosensory evoked potentials in response to conventional nerve stimuli failed in objectifying the diagnosis. As such, evoked cerebral potentials in response to laser heat stimuli applied to the hairy skin can be used for an overall examination of the functional integrity of peripheral small fibres, anterolateral tracts and thalamocortical projections.
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Review Case Reports
[Cerebral crossed diaschisis caused by cerebellar lesion: role of the cerebellum in mental functions].
In 3 patients with a stroke limited to the posterior fossa, regional cerebral blood Flows were measured by the 133 Xe inhalation method (the first two cases) or by the SPECT with HMPAO method (the third case). The first patient had a median and paramedian hematoma of the left cerebellar hemisphere and the left dorsolateral portion of the pons. Remote cerebral hypoperfusion, measured 3 months later, was observed in both frontal premotor regions (but more marked in the right hemisphere) and in a circumscribed area of the right temporal region. ⋯ In the absence of supratentorial insult, and during the hemodynamical stable phase, crossed cerebello-cerebral diaschisis is suggested in our 3 patients. Although it is too early to draw definite conclusions, our findings may: (1) confirm the functional interconnections between the cerebellum and the cerebrum in man and (2) provide functional basis for the behavioral function impairment reported in patients with cerebellar insult. Further rCBF, metabolism, and pathologic studies on this subject are required to elucidate this issue.
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The possible associations of myoclonic phenomena, progressive or non progressive encephalopathies and epileptic phenomena are reviewed with special emphasis on childhood. This leads to the following five groups of conditions: (1) myoclonus without encephalopathy and without epilepsy; (2) encephalopathies with non-epileptic myoclonus; (3) progressive encephalopathies with myoclonic seizures or epileptic syndromes (Progressive myoclonus epilepsies); (4) epileptic encephalopathies with myoclonic seizures; (5) myoclonic epilepsies. In the first group, which also includes physiological myoclonus, a more thorough description of "benign sleep myoclonus of newborn" and "benign myoclonus of early infancy" is given. ⋯ The assumption is that diffuse and persistent epileptic activity may interfere with normal development of the higher cerebral functions. "West syndrome" and "Lennox-Gastaut syndrome" are the more representative examples and may present with myoclonic type of seizures, but they are not dealt with in detail here. Group 5 comprises true myoclonic epilepsies, differentiating syndromes recognized as idiopathic, such as "benign myoclonic epilepsy of infancy" and "juvenile myoclonic epilepsy", from those which are cryptogenic and carry a more cautious prognosis--i.e.: "cryptogenic myoclonic and myoclono-astatic epilepsies" and "Severe myoclonic epilepsy of infancy". Finally other epileptic syndromes usually not considered as myoclonic epilepsies, but presenting sometimes myoclonic seizures, are mentioned.
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Peripheral neuropathy has attracted relatively little attention in mitochondrial myopathy. However, mitochondrial myopathies are clinically heterogeneous disorders that can affect multiple systems including peripheral nerves other than the skeletal muscle. In addition to the survey of the literature, we studied 6 cases of mitochondrial myopathy with peripheral neuropathy; 3 cases of oligo-systemic involvement confined mainly to skeletal muscles and peripheral nerves, and 3 cases of multi-systemic involvement diagnosed as myoclonus epilepsy with ragged-red fibers (MERRF) or mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). ⋯ Electrophysiological findings include decreased nerve conduction velocities and neuropathic electromyograms. Peripheral nerves show loss of myelinated fibers, particularly of large ones, and the remaining fibers have disproportionately thin myelin sheaths with or without onion-bulb formation. Thus the pathological process is axonal degeneration with demyelination resulting from involvement of both neurons (axons) and Schwann cells.