Permutation Entropy and Signal Energy Increase the Accuracy of Neuropathic Change Detection in Needle EMG.

Background and Objective. Needle electromyography can be used to detect the number of changes and morphological changes in motor unit potentials of patients with axonal neuropathy. General mathematical methods of pattern recognition and signal analysis were applied to recognize neuropathic changes. This study validates the possibility of extending and refining turns-amplitude analysis using permutation entropy and signal energy. Methods. In this study, we examined needle electromyography in 40 neuropathic individuals and 40 controls. The number of turns, amplitude between turns, signal energy, and "permutation entropy" were used as features for support vector machine classification. Results. The obtained results proved the superior classification performance of the combinations of all of the above-mentioned features compared to the combinations of fewer features. The lowest accuracy from the tested combinations of features had peak-ratio analysis. Conclusion. Using the combination of permutation entropy with signal energy, number of turns and mean amplitude in SVM classification can be used to refine the diagnosis of polyneuropathies examined by needle electromyography.

[Somatosensoric prosthesis for the blind]. / Somatosenzorická protéza pro slepce.

At present vision prosthesis proposes transmission of only a limited amount of visual information. Cutaneous receptor field may serve as a information channel. It has similar information-processing ability as retina. Lower information capacity of the skin may be compensated by wavelet transform image compression. Advances in microtechnology have facilitated the development of a haptic data visualization system with sufficient life-time for people with visual impairments. Proposed array with 2400 carbon electrodes stewed on elastic membrane in the present experiments demonstrate a good mechanical endurance, electrical stability and adhesivity to the trunk skin. Disadvantageous is short circuits production among near electrodes due to sweating and skin irritation after long term electrical stimulation. Vibrotactile piezo-electric stimulators are safer alternative with lower resolution. Comparing retinal and cortical vision prosthesis offers electrocutaneous communication system comparably higher amount of transmitted information.

New England medical center posterior circulation stroke registry: I. Methods, data base, distribution of brain lesions, stroke mechanisms, and outcomes.

Among 407 New England Medical Center Posterior Circulation Registry (NEMC-PCR) patients, 59% had strokes without transient ischemic attacks (TIAs), 24% had TIAs before strokes, and 16% had only posterior circulation TIAs. Embolism was the commonest stroke mechanism accounting for 40% of cases (24% cardiac origin, 14% arterial origin, 2% had potential cardiac and arterial sources). In 32%, large artery occlusive lesions caused hemodynamic brain infarction. Stroke mechanisms in the posterior and anterior circulation are very similar. Infarcts most often included the distal posterior circulation territory (rostral brainstem, superior cerebellum and occipital and temporal lobes), while the proximal (medulla and posterior inferior cerebellum) and middle (pons and anterior inferior cerebellum) territories were equally involved. Infarcts that included the distal territory were twice as common as those that included the proximal or middle territories. Most distal territory infarcts were attributable to embolism. Thirty day mortality was low (3.6%). Embolic stroke mechanism, distal territory location, and basilar artery occlusive disease conveyed the worst prognosis.

New England Medical Center Posterior Circulation Stroke Registry II. Vascular Lesions.

Among 407 New England Medical Center Posterior Circulation Registry (NEMC-PCR) patients, the extracranial (ECVA) and intracranial vertebral arteries (ICVA) were the commonest sites of severe occlusive disease followed by the basilar artery (BA). Severe occlusive lesions were found in >1 large artery in 148 patients; 134 had unilateral or bilateral severe disease at one arterial location. Single arterial site occlusive disease occurred most often in the ECVA (52 patients, 15 bilateral) followed by the ICVA (40 patients, 12 bilateral) and the BA (46 patients). Involvement of the ICVAs and the BA was very common and some patients also had ECVA lesions. Hypertension, smoking, and coronary and peripheral vascular disease were most prevalent in patients with extracranial disease while diabetes and hyperlipidemia were more common when occlusive lesions were only intracranial. Intra-arterial embolism was the most common mechanism of brain infarction in patients with ECVA and ICVA occlusive disease. ICVA occlusive lesions infrequently caused infarction limited to the proximal territory (medulla and posterior inferior cerebellum). BA lesions most often caused infarcts limited to the middle posterior circulation territory (pons and anterior inferior cerebellum). Posterior cerebral artery occlusive lesions were predominantly embolic. Penetrating artery disease caused mostly pontine and thalamic infarcts. Prognosis was poorest in patients with BA disease. The best prognosis surprisingly was in patients who had multiple arterial occlusive lesions; they often had position-sensitive transient ischemic attacks during months or years.

Expanding the phenotypic spectrum of the CACNA1A gene T666M mutation: a description of 5 families with familial hemiplegic migraine.

BACKGROUND: Familial hemiplegic migraine (FHM) is a rare autosomal dominant subtype of migraine with aura. Missense mutations in the chromosome 19 CACNA1A calcium channel gene have been found in approximately half of the families. The T666M mutation, replacing a threonine by a methionine at residue number 666, is the most frequent mutation, reported in 14 independent FHM families; other mutations have so far been described in only 1 or 2 families each. The clinical features of T666M families have been reported, but the course is unknown. OBJECTIVE: To present a detailed description of the clinical features of new FHM families in which we identified the T666M mutation in our CACNA1A screening program. METHODS: As part of our ongoing genetic screening, mutation analysis of the CACNA1A gene was performed by single-strand conformational polymorphism analysis in 33 probands of families with FHM. RESULTS: We identified the T666M mutation in 5 unrelated FHM families. In 3 of the families, patients displayed cerebellar ataxia. In 1 family, some affected members with the mutation had attacks with confusion but without hemiparesis. In 1 family, patients had progressive cognitive dysfunction. CONCLUSIONS: The T666M mutation is the most frequent CACNA1A mutation in FHM; it was found in 5 of 33 FHM families at our laboratory, and in 19 of 39 families with a known mutation reported in the literature (including the present study). Screening for the T666M mutation should therefore be the first step when screening families with FHM. There is a remarkable clinical heterogeneity among families with the T666M mutation.

Primary orthostatic tremor with prominent muscle hypertrophy.

A 33-year-old woman had a 6-year history of progressive postural instability on standing and with walking. There was progressive asymmetric lower limb muscle hypertrophy affecting thigh and calf musculature. Surface EMG recordings showed the rapid development of a synchronized motor unit discharge at a frequency of 17.5 Hz on standing, characteristic of primary orthostatic tremor. These observations suggest that primary orthostatic tremor can be associated with gait disturbance and should be considered in the differential diagnosis of unexplained muscle hypertrophy.