A primer on electrophysiologic studies in myopathy

Electromyography and nerve conduction studies are the primary electrodiagnostic studies employed in the evaluation of patients with weakness and suspected myopathy. This article discusses the physiologic principles that serve as a framework for understanding the purpose, limitations, and interpretation of these tests. In the process the authors also review the differential diagnosis of myopathy.     

人体针刺操作实践对手指精细触觉的影响

目的:研究人体针刺操作实践对手指精细触觉敏感度的影响,以深入认识操作者的得气感知过程,挖掘影响得气感判断能力的关键因素。方法:运用皮肤感觉阈和两点辨别阈等精细触觉测试指标,测试15名针灸执业医师双手拇指、食指及中指的皮肤精细触觉,并与15名普通人进行对照,分析针灸医师与普通人的精细触觉差异。结果:针灸医师押手的皮肤感觉阈和两点辨别阈与普通人非利手相近,而针灸医师刺手的皮肤感觉阈和两点辨别阈与普通人利手相比均有降低趋势,尤其以食指更为明显。结论:手指皮肤精细触觉是影响得气感知能力的关键因素,长期人体针刺操作实践可以适应性提高操作者持针手指皮肤精细触觉的敏感度。     

Un nouveau regard sur la sémiologie motrice en psychiatrie : de la physiologie du mouvement moteur volontaire aux résultats d’imagerie fonctionnelle dans les troubles de conversion

Are the conversion disorders beyond medical disorders? Lived as a reality by the patient, the absence of “objectives” signs at the clinical examination have for a long time considered these conversion disorders as “pathologies without substrates”. However, if the clinic of these disorders is well known, its precise understanding remains subject to debate and the exact mechanisms that produce it are poorly understood. Does the fact that explanatory lesions in the brain are not found, exclude the possibility of functional abnormalities in this organ? It is often called these disorders “disease of the imagination or the will”, but in fact, we know little about the brain functioning of voluntary motor movement and mental representation in conversion disorders. So with this in mind, what could be the contribution of “modern” techniques of investigations such as functional imaging? Would the identification of functional abnormalities in the brain allow opening new theoretical perspectives for these patients? Functional imaging has explored more complex mechanisms considered some years ago as inaccessible (e.g. emotions, affective states, volition, mental imagery, unconscious processes), and we propose in this paper to show how, using these techniques, a pathology considered as a diagnosis of exclusion and a disorder without substrate can be approached differently through “new” neurophysiological explanation.     

Relation between language, audio-vocal psycholinguistic abilities and P300 in children having specific language impairment

Specific language impairment is a relatively common developmental condition in which a child fails to develop language at the typical rate despite normal general intellectual abilities, adequate exposure to language, and in the absence of hearing impairments, or neurological or psychiatric disorders. There is much controversy about the extent to which the auditory processing deficits are important in the genesis specific language impairment. The objective of this paper is to assess the higher cortical functions in children with specific language impairment, through assessing neurophysiological changes in order to correlate the results with the clinical picture of the patients to choose the proper rehabilitation training program.

Subjects and method

This study was carried out on 40 children diagnosed to have specific language impairment and 20 normal children as a control group. All children were subjected to the assessment protocol applied in Kasr El-Aini hospital. They were also subjected to a language test (receptive, expressive and total language items), the audio-vocal items of Illinois test of psycholinguistic (auditory reception, auditory association, verbal expression, grammatical closure, auditory sequential memory and sound blending) as well as audiological assessment that included peripheral audiological and P300amplitude and latency assessment.The results revealed a highly significant difference in P300 amplitude and latency between specific language impairment group and control group. There is also strong correlations between P300 latency and the grammatical closure, auditory sequential memory and sound blending, while significant correlation between the P300 amplitude and auditory association and verbal expression.

Conclusion

Children with specific language impairment, in spite of the normal peripheral hearing, have evidence of cognitive and central auditory processing defects as evidenced by P300 auditory event related potential in the form of prolonged latency which indicate a slow rate of processing and defective memory as evidenced by small amplitude. These findings affect cognitive and language development in specific language impairment children and should be considered during planning the intervention program.     

Health-related quality of life in type 1 diabetic patients and influence of peripheral nerve involvement

We examined the relationships between diabetic peripheral nerve involvement and patients' own perception of quality of life in a multidimensional study based on outcome research recommendations. The study enrolled 50 consecutive outpatients with type 1 diabetes mellitus (23 men, 27 women; mean age, 40.1 years). The patients were evaluated with validated clinical tests (e. g. Semmes-Weinstein, vibration perception threshold, muscle strength), neurophysiological tests (sural, peroneal and ulnar nerves) and patient-oriented (SF-36 and NASS) questionnaires. Patient-oriented physical scores were significantly related with: (1) neurophysiological findings of the lower limbs; (2) conventional measurements of sensitivity. Conversely, patient-oriented mental scores were not related with these findings. The patient-oriented questionnaires provided an important perspective of the severity of the disease, often closely related with the biological parameters. They offered new interpretations to conventional biological measurements. In particular, the peripheral nerve picture was strictly related to the physical aspects of the patients' quality of life, and not with the mental aspects. Received: 13 October 2000 / Accepted in revised form: 28 June 2001     

Ulnar neuropathy at the elbow: Reappraisal of the wrist-upper arm latency difference between ulnar and median nerves

ObjectivesTo evaluate the sensitivity and specificity of the latency difference (DLat) between ulnar and median nerves of the arm after stimulation at the wrist; one of the easiest techniques proposed for recognizing ulnar neuropathy at the elbow (UNE). As latency difference is not a standardized technique, we set up a multicenter study to recruit large numbers of normal subjects and patients with UNE or generalized neuropathy.MethodsSix centers participated in the study with data obtained from three groups of participants, controls (CTRLs), patients with UNE and patients with generalized neuropathy (GNP).We first verified the anatomical superposition of the ulnar and median nerves in cadaver examination. The optimal recording site for these two nerves was found to be 10 cm above the medial epicondyle. We then standardized the position of the arm with full extension of the elbow and stimulated first the median and then the ulnar nerves at the wrist. CTRLs were examined on both arms at two consecutive visits.ResultsWe recorded 32 idiopathic UNE cases, 44 GNP patients and 62 controls.We demonstrated that a DLat cut-off value of 0.69 ms brings a sensitivity of 0.86 and specificity of 0.89 to discriminate CTRLs from UNE. We also validated that intra-examiner reproducibility was good.ConclusionWe report a lower normal value for DLat than reported in several non-standardized studies and CTRL and UNE groups have clearly separated DLat values.SignificanceDue to its high sensitivity, our standardized technique could be used as a first-line diagnostic tool when UNE is suspected.     

Neurophysiological assessment of peripheral nerve and spinal cord function in asymptomatic HIV-1 infection: Results from the UCMSM/Medical Research Council neurology cohort

As part of the Medical Research Council prospective study of the neurological complications of HIV infection, neurophysiological tests of spinal cord and peripheral nerve function were recorded in a cohort of homosexual or bisexual men. The studies included motor and sensory nerve conduction studies, vibration perception thresholds, somatosensory evoked potentials and motor evoked potentials elicited by magnetic stimulation. The results were compared with markers of immune function. The findings from 114 volunteers were analysed in a cross-sectional study. Fifty-nine were HIV-seropositive but asymptomatic, 26 had progressed to the symptomatic stages of HIV disease and 29 were persistently HIV-seronegative. There was some evidence of a mild sensory axonopathy in the symptomatic HIV-seropositive group. No differences were detected between the asymptomatic HIV-seropositive group and the HIV-seronegative comparison group. There were no consistently significant correlations between the neurophysiological measurements and CD4 counts and ₂-microglobulin levels. On repeated testing, there was no evidence of a trend towards deterioration over a mean period of approximately 3 years in 36 HIV-seropositive subjects who remained asymptomatic compared with 22 HIV-seronegatives. These findings have failed to demonstrate neurophysiological evidence of spinal cord or peripheral nerve dysfunction in the asymptomatic stages of HIV infection.     

A survey of the pattern reversal visual evoked response (PRVER) in 1428 consecutive patients referred to a clinical neurophysiology department

The records of 1428 neurological patients referred to a department of Clinical Neurophysiology for PRVER testing have been reviewed. Half field studies with multichannel recordings were carried out in the majority. 1186 of these patients had a provisional diagnosis of MS; 42% had abnormal PRVERs compared with 25% for those patients who did not have MS. Symmetrical latency increases from stimulation of either eye, interocular latency abnormalities and amplitude abnormalities were as frequent in the non-MS patients as the group with a provisional diagnosis of MS. A small proportion of patients had neurophysiological evidence of field defects; homonymous hemianopias occurred as frequently as "central" defects in the MS group. The PRVER abnormalities are considered in relation to the current models of conduction in demyelinated fibres.