Biomedical subjects
Publications and source records attributed to M J Kothari.
In this report, a young female, who initially presented with left upper extremity pain, eventually underwent surgery for presumed thoracic outlet syndrome. Following surgery, she developed shortness of breath. Diagnostic studies revealed an elevated left hemidiaphragm secondary to injury to the phrenic nerve.
Although the reproducibility of motor unit number estimation (MUNE) for groups of subjects has been studied, there is little such data for individuals. Prediction intervals represent a tool to study individual MUNE reproducibility and represent the range of values expected for a future MUNE if the true number of motor units remains unchanged. MUNE was performed using the statistical method on 48 normal individuals. The prediction interval was found to be a function of the intrasubject coefficient of variation. Using a commercial manufacturer's recommended technique and software, prediction intervals were found to be so broad as to be of uncertain value. We found that by averaging two MUNE observations for each determination, and using the method of weighted averages for calculating the size of an average single motor unit potential, the intrasubject coefficient of variation was reduced from 16.48% to 8.77%, and the 90% prediction interval became sufficiently narrow to be clinically useful. False-negative rates were also lowered substantially using these techniques. Thus, simple modifications of an existing MUNE program improved the clinical utility of this program for the longitudinal study of patients in whom changes in motor unit number over time are of importance, such as those with motor neuron diseases.
Explore the source record for details and available documents.
The authors report the case of a 60-year-old man with respiratory distress secondary to exacerbation of chronic obstructive pulmonary disease, right lower lobe pneumonia, and severe bronchospasm. High doses of lorazepam were given intravenously after failure to control bronchospasm and agitation with bronchodilators and mucolytic agents; the patient was unresponsive to all stimuli while receiving lorazepam. Electroencephalography revealed a profoundly suppressed pattern without accompanying low-voltage fast activity--this was reversible following withdrawal of the lorazepam.
Four patients with painless, progressive focal neurological deficits that localized to peripheral nerve or plexus were eventually found to have the relatively rare condition of localized hypertrophic neuropathy or intraneural perineurioma. Magnetic resonance imaging (MRI) was an excellent tool for aiding in the precise localization of the lesion, if specifically tailored with regard to imaging planes and specific MRI sequences. Fat-saturated T2-weighted and fat-saturated T1-weighted postgadolinium images provided the best visualization, particularly with a high-field magnet and phase array body coil. Two patients stabilized following resection of the lesion and sural nerve grafting, and 1 had partial improvement in a proximal muscle following neurolysis.
This study examined the severity of symptoms in carpal tunnel syndrome (CTS) in relation to nerve conduction measures of the median nerve. Clinical symptom severity and nerve conduction studies were evaluated for 64 hands with CTS in 45 patients. We found the following: (1) significant relationships identified among the clinical scales resulted in a dichotomous symptom classification scheme into primary and secondary symptoms, with the former being more specific for those symptoms usually seen in association with nerve injury; (2) there were significant relationships between symptom severity and nerve conduction abnormality; (3) the primary symptom scale correlated more strongly with the electrodiagnostic measures of nerve injury than did the secondary symptom scale. Based on these findings, we believe that these clinical scales have biological significance and reflect median nerve injury. This would support their potential utility for evaluating the outcome of CTS treatment and developing a model for exposure-severity relationship.
Compression of the ulnar nerve at the level of the wrist is rare and often difficult to diagnose. This article describes the various types of lesions that may occur and discusses the different electrophysiologic techniques that may aid the electromyographer in localizing lesions to the wrist.
The case of a young woman with basilar artery dissection, possibly precipitated by trauma, is presented, and the literature is reviewed.
Over 3 years, we studied 8 patients with neurogenic thoracic outlet syndrome (TOS) and tested the medial antebrachial sensory response (MASR) to determine its diagnostic value. The MASR and ulnar sensory response (USR) were abnormal in all 8 patients. Seven had a low median motor response (MMR) with a low USR. In 1, the MASR and USR were abnormal but the MMR was normal. We conclude that the MASR is of diagnostic value in patients with neurogenic TOS.
OBJECTIVE: Ulnar neuropathy at the elbow is often difficult to localize by standard electrophysiologic testing. This study compared three ulnar nerve conduction studies to determine which was more sensitive in localizing ulnar neuropathy at the elbow. METHODS: Motor studies to the first dorsal interosseous and the abductor digiti quinti and a mixed ulnar nerve sensory study across the elbow. RESULTS: Motor studies to the first dorsal interosseous and abductor digiti quinti were abnormal in 81% and 71% of patients, respectively. The ulnar mixed sensory study across the elbow was abnormal in 57%. In 38%, all three tests were abnormal. CONCLUSION: Motor studies were more sensitive than the ulnar mixed sensory study across the elbow in localizing ulnar neuropathy of the elbow.
OBJECTIVE: Electrodiagnostic testing (electromyography [EMG] and nerve conduction studies [NCS]) may result in some patient discomfort. The justification for such testing should be based on the expectation that the results will affect patient management. This study was conducted to determine how frequently the results of EMG/NCS change the clinical management of the patient. METHODS: One investigator (MB) spoke to each referring physician after EMG/NCS to determine if any management decisions were altered by the test. RESULTS: One hundred forty consecutive EMG/NCS records were obtained. Follow-up was available on 100 patients. Of 78 patients with abnormal findings on EMG/NCS, 29 (37%) had a diagnosis different from the referring diagnosis. For 43 of the 78 (55%), the physician reported that additional diagnostic testing was undertaken or treatment plans were altered. CONCLUSION: EMG/NCS are useful, informative, and diagnostic in the management of various neurologic disorders.
Explore the source record for details and available documents.
Although the effect of low temperature on the peripheral nervous system has been systematically studied, the effect of high temperature has not. We investigated the effect of elevating limb temperature from 32 degrees C to 42 degrees C by performing sequential motor studies, antidromic sensory studies, and 3-Hz repetitive stimulation in normal subjects. In addition, we recorded single motor units by using threshold stimulation. On average, motor amplitude and duration decreased by 27% and 19%, respectively, whereas sensory amplitude and duration decreased by 50% and 26%, respectively. Neuromuscular transmission remained normal at 42 degrees C. Single motor unit recordings revealed a reduction in amplitude of 26%, similar to the overall reduction in compound motor amplitude. These findings demonstrate that significant reductions in sensory and motor amplitudes can occur in normal nerves at high temperature; we hypothesize that these changes are secondary to alterations in nerve and muscle ion channel function.
As proximal nerves are relatively spared in length-dependent, axonal polyneuropathy, we theorized that a sural/radial amplitude ratio (SRAR) might be a sensitive indicator of mild polyneuropathy. In this study, sural amplitudes and SRARs in patients with signs of mild axonal polyneuropathy were compared to those of normal, age-matched control subjects. Sural and radial sensory responses were measured in a standard fashion in all subjects. Thirty polyneuropathy patients had an average SRAR of 0.29 as compared to 0.71 for the 30 normal subjects. An SRAR of less than 0.40 was a strong predictor of axonal polyneuropathy, with 90% sensitivity and 90% specificity, as compared to an absolute sural amplitude of less than 6.0 microV, which had sensitivity of only 66%. Additionally, unlike the sural amplitude, the ratio did not vary significantly with age. We conclude that the SRAR is a sensitive, specific, age-independent electrodiagnostic test for mild axonal polyneuropathy.
Bilateral facial paralysis of diverse infectious aetiologies has been reported in HIV infected patients. We present a patient with bilateral facial palsy most likely due to herpes zoster meningoencephalitis in a patient with neutropenia and who subsequently tested HIV-positive.
Diastematomyelia is a form of an occult dysraphism, which can present with lower urinary tract dysfunction. We present the findings in 21 patients with diastematomyelia evaluated at the Children's Hospital in Boston. Seventy-six percent of the patients were female. Eighty-six per cent had a cutaneous lesion present overlying the spine. Urodynamic and electrophysiologic studies showed abnormalities in 17 (81%) of 21 patients, of whom 13 (62%) had upper motor neuron dysfunction. Seventeen patients underwent corrective spinal surgery and none of the patients deteriorated on a follow-up urodynamic and electrophysiologic study. We recommend that patients with cutaneous, midline lower back lesions with or without lower urinary tract dysfunction be evaluated with a urodynamic and electrophysiologic study to characterize the extent of neurologic and urologic dysfunction.
Explore the source record for details and available documents.
Ulnar nerve entrapment at the wrist (UNW) is uncommon and often difficult to localize electrophysiologically. The difference between the motor latencies to the median-innervated second lumbrical (2L) and ulnar-innervated palmar interosseous (Pl) (Diff 2L-Pl) has been shown to be of localizing value in patients with median neuropathy at the wrist. In the last year, we evaluated 2 patients with clinically definite ulnar neuropathy at the wrist. We performed motor studies to the 2L-Pl on the 2 patients and 12 disease controls with ulnar neuropathy at the elbow as follows: Using the same electrodes to record both the 2L and Pl, the median and ulnar nerves were each stimulated supramaximally above the wrist using identical distances. In the disease control subjects, the Diff 2L-Pl was essentially the same as normal controls (mean [0.13], range [(-0.3)-0.4]). In both patients with UNW, the Diff 2L-Pl clearly supported the routine electrophysiological studies in localizing the lesion (ulnar latencies were 1.1 and 1.8 ms longer than the median latencies). We conclude that the lumbrical-interosseous latency difference is useful in localizing ulnar nerve entrapment to the wrist.