Lateral asymmetry of motor unit number estimate (MUNE).

The aspects of lateral asymmetry of the peripheral nervous system have been investigated to a lesser extent than the aspects of lateral asymmetry in the central nervous system. We utilized a statistical method of quantitative MUNE to demonstrate lateral asymmetry of the motor units in healthy individuals, revealing higher values in the nondominant hand. Awareness of this phenomenon will improve the accuracy and reliability of this MUNE method when used in clinical trials.

Painless electrodiagnostic current perception threshold and pain tolerance threshold values in CRPS subjects and healthy controls: a multicenter study.

The purpose of this study is to evaluate both painless and painful sensory transmission in patients with Complex Regional Pain Syndrome (CRPS) using the automated electrodiagnostic sensory Nerve Conduction Threshold (sNCT) test. This test generates reliable, painless Current Perception Threshold (CPT) and atraumatic Pain Tolerance Threshold (PTT) measures. Standardized CPT and PTT measures using constant alternating current sinusoid waveform stimulus at 3 different frequencies 5 Hz, 250 Hz, and 2 kHz (Neurometer CPT/C Neurotron, Inc. Baltimore, MD) were obtained from CRPS subjects at a distal phalange of the affected extremity and at an ipsilateral asymptomatic control site. Matched sites were tested on healthy subjects. Detection sensitivities for an abnormal PTT and CPT test were calculated based on specificity of 90% as determined from data obtained from healthy controls. A Spearman rank correlation was used to test for a significant association between presence of allodynia and an abnormal PTT or CPT at any frequency tested. Thirty-six CRPS subjects and 57 healthy controls were tested. The highest detection sensitivity of the PTT test from symptomatic test sites was 63% for the finger and 71% for the toe. PTT abnormalities were also detected, to a lesser degree, at the asymptomatic control site (41% finger control site, 16% toe control site). The highest CPT detection sensitivity at the symptomatic site was 37% for the finger site and 53% for the toe site. CPT abnormalities were also detected at the asymptomatic control site (29% finger control site, 37% toe control site). Eighty-six percent of the CRPS subjects had either a PTT or CPT abnormality at any frequency at the symptomatic site. There was a significant correlation between presence of allodynia and presence of an abnormal CPT and PTT, respectively (P < .01). The correlation coefficient was lower for CPT than for PTT, ie, 0.34 versus 0.6 for the finger and 0.48 versus 0.67 for the toe, respectively. In studied CRPS patients an abnormal PTT was detected with higher sensitivity than an abnormal CPT. Assessing PTT may become a useful electrodiagnostic quantitative sensory test for diagnosing and following the course of neuropathic pain conditions.

Role of central conduction time and motor evoked response amplitude in predicting stroke outcome.

Central motor conduction studies were done in 38 patients with first time unilateral cortical or sub-cortical stroke. Central conduction time and MEP amplitude were correlated with the percentage of change in the recovery score three months after stroke. A significant correlation was seen with recovery of muscle strength and the amplitude of the MEP. The study showed that central motor conduction studies would be a good tool for predicting stroke outcome.

Motor unit number estimate (MUNE) testing in male patients with mild to moderate carpal tunnel syndrome.

Carpal tunnel syndrome is a frequent clinical entity with an excellent prognosis if adequately treated. However, in rare cases of treatment failure, patients may suffer significant impairment of hand function with various degrees of disability. Loss of motor units in the hand muscles is the pathophysiological basis for this functional impairment. In our study we utilized motor unit number estimate (MUNE) testing in patients with mild to moderate carpal tunnel syndrome in an attempt to identify a patient population with a "silent" loss of motor units in the affected hand. As a result of the study we identified two groups of such patients; first, the group with an associated cervical radiculopathy, and second, the group with an increased amount of polyphasic motor units in the abductor pollicis brevis muscle on electromyographic (EMG) evaluation. Potentially, these patient populations are predisposed for functional impairment of the hand and, therefore, require a more active diagnostic and therapeutic evaluation. Our study also indicates that morphology of motor unit potentials is a good indicator of the motor unit reserve and correlates well with our MUNE results. MUNE testing proved to be a well tolerated, reliable and practical technique in the diagnosis, treatment and research of neuromuscular disorders.

Gait in patients with cerebellar ataxia.

The gait pattern in 10 patients with cerebellar degenerations was studied and the results were compared with 10 matched normal subjects, seeking the principal patterns in this disorder. Gait at natural speed was studied in a biomechanics laboratory using a video-based kinematic data acquisition system for measuring body movements. Patients showed a reduced step and stride length with a trend to reduced cadence. Heel off time, toe off time, and time of peak flexion of the knee in swing were all delayed. Range of motion of ankle, knee, and hip were all reduced, but only ankle range of motion reached significance. Multijoint coordination was impaired, as indicated by a relatively greater delay of plantar flexion of the ankle compared with flexion of the knee and a relatively late knee flexion compared with hip flexion at the onset of swing. The patients also showed increased variability of almost all measures. Although some of the deviations from normal were simply the result of slowness of walking, the gait pattern of patients with cerebellar degeneration shows incoordination similar to that previously described for their multijoint limb motion.

Periodic complexes, absence-like status and suppression-burst pattern in coma following cardiorespiratory arrest.

A 75-year-old man suffered a cardiac arrest and severe anoxic encephalopathy. A serial study of electroencephalograms during 4 days showed sequential changes from periodic approximately 2 Hz spike activity to absence-like status (ALS) and then into a suppression-burst pattern. Intravenous administration of phenytoin had no effect on ALS. A small dose of intravenous diazepam reduced a suppression-burst pattern. We speculate that the ALS originates in the midline structures, spreading bilaterally and synchronously to the "dysfunctional" cortex; the sustained discharges were a manifestation of associated reticular lesions, and we believe that intravenous diazepam suppressed the spread of ALS to the "dysfunctional cortex," leading to the appearance of the suppression-burst pattern. The only limitation for definitive conclusions may be a lack of postmortem verification. Autopsy findings, however, could not have confirmed the dynamic changes that occurred during the 5 days before the patients death.

Peripheral nerve functions improve in chronic alcoholic patients on abstinence.

We studied the peripheral nerve functions of 24 chronic alcoholic patients admitted to the alcohol rehabilitation ward. The study included clinical examination, detailed evaluation of nutritional status, quantitative vibration sense estimation and electrodiagnostic study of the peripheral nerves in the upper and lower limbs. During the subsequent 6 months all of the above measures were repeated at invervals of 1, 3 and 6 months, while the patients abstained from alcohol. Several of the parameters studied showed mild but definite improvement during 6 months.

Respiratory failure revealing mitochondrial myopathy in adults.

Two patients, a 70-yr-old black woman and a 56-yr-old black man, presented with respiratory failure unexplained by intrinsic lung disease. Both had been dependent on a respirator for several weeks. No abnormalities of the central or peripheral nervous system or long-standing muscle weakness was noted. The findings from ophthalmologic and cardiac evaluations were normal. The serum creatinine kinase concentration was mildly elevated in case 1, and needle electromyography showed myopathic potentials in case 2. In both instances, muscle biopsy established the diagnosis of mitochondrial myopathy. Biochemical studies of muscle extracts showed partial deficiency of complex 3 in patient 2 and of complex 4 in patient 1. Both patients were weaned from the ventilator after long periods of ventilatory assistance. These observations document a hitherto undescribed presentation of adult-onset mitochondrial myopathy.

Refractory studies in early detection of carpal tunnel syndrome.

We studied refractory periods of the median sensory nerves in 10 patients with mild carpal tunnel syndrome (CTS), and compared them with the median sensory refractory studies on normal subjects. Our data showed that relative refractory period (RRP) studies are useful in diagnosing early CTS.

Peripheral nerve functions in chronic alcoholic patients on disulfiram: a six month follow up.

The peripheral nerve functions of chronic alcoholic patients were studied clinically and electrophysiologically before they were placed on disulfiram (Antabuse). The evaluations were repeated while they were treated with 250 mg (n = 33) and 125 mg (n = 9) of disulfiram for one, three and six months. The data were compared with that of 24 untreated chronic alcoholic patients. None of the patients developed overt symptoms of peripheral neuropathy during the period of study. The patients on 250 mg disulfiram showed a significant decline in several components of the peripheral nerve functions, but no significant electrophysiological abnormalities were noted in patients taking 125 mg of disulfiram. Interestingly, the control group showed a significant electrophysiological improvement during the same period of observation.

Sciatic nerve compression: diagnostic value of electromyography and computerized tomography.

A 54 year old man on long term anticoagulation (warfarin) treatment for prosthetic heart valve, developed sciatic nerve compression and femoral nerve dysfunction due to hematoma and edema in the gluteal muscles. Computerized tomography of the pelvis and electrodiagnostic studies helped in localizing and understanding the pathophysiology of the clinical signs and symptoms.

A technique for studying the greater auricular nerve conduction velocity.

A technique for studying sensory nerve conduction velocity of the greater auricular nerve according to one of the conventional methods is described. Latency and conduction velocities obtained from 35 nerves in 20 healthy adults were 1.7 +/- 0.2 msec (SD) and 46.8 +/- 6.6 m/sec (SD), respectively. This technique is easy to perform and is useful in documenting traumatic and other neuropathies involving the greater auricular nerve, as illustrated in the case report in this article.