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M J Kothari

Publications and source records attributed to M J Kothari.

At least 19 recordsLinked to original sources
PubMed1998

Medial antebrachial cutaneous sensory studies in the evaluation of neurogenic thoracic outlet syndrome.

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.

Action Potentials↗
PubMed1998

Three ulnar nerve conduction studies in patients with ulnar neuropathy at the elbow.

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.

Adult↗
PubMed1997

Nerve, muscle, and neuromuscular junction electrophysiology at high temperature.

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.

Action Potentials↗
PubMed1997

Sural/radial amplitude ratio in the diagnosis of mild axonal polyneuropathy.

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.

Adult↗
PubMed1997

Urodynamic and neurophysiologic evaluation of patients with diastematomyelia.

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.

Adolescent↗
PubMed1996

Lumbrical-interossei motor studies localize ulnar neuropathy at the wrist.

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.

Adult↗
PubMed1996

Urinary dysfunction in Duchenne muscular dystrophy.

In Duchenne muscular dystrophy (DMD), sphincter muscles tend to be clinically spared. However, urinary incontinence is occasionally reported, usually late in the course of the disease. We wished to determine the etiology of urinary dysfunction in patients with DMD. Seven boys with DMD and urinary dysfunction were examined by a neurologist and a urologist followed by urodynamic and electrophysiological assessment. Based on the results of these evaluations, patients were defined as having an upper motor neuron (UMN), lower motor neuron (LMN), or myopathic lesion. Five of the patients had UMN abnormalities consisting of either uninhibited contractions or bladder/sphincter dyssynergy. One patient had a LMN lesion with prolonged duration and high-amplitude motor units. No patient demonstrated myopathic motor units. Five boys had undergone spinal fusion for scoliosis. We conclude that urinary incontinence in DMD is most often due to UMN dysfunction and not due to a severe myopathy of the detrusor or external sphincter. The most likely causes of the UMN abnormalities are severe scoliosis or a complication of spinal fusion surgery.

Adolescent↗
PubMed1996

Coexistent entrapment neuropathies in patients with amyotrophic lateral sclerosis.

OBJECTIVE: To determine the incidence of entrapment neuropathy in patients with amyotrophic lateral sclerosis (ALS). Although it is well known that patients with motor neuron disease may have coexisting focal neuropathies, their prevalence has not been previously determined. METHODS: Electrophysiologic studies (EMG/NCS) were reviewed from 126 patients with ALS seen at a university-affiliated hospital from 1991 to 1994. Every patient had an EMG/ NCS consistent with motor neuron disease (i.e., active and chronic denervation in at least 3 body regions). RESULTS: Forty-three percent (54 patients) had evidence of a neuropathy. Abnormalities included median neuropathy at the wrist in 15 (12%), ulnar neuropathy at the elbow in 18 (14%), nonlocalized ulnar neuropathy in 10 (8%), and peroneal neuropathy at the fibular head in 2 (2%). Furthermore, 9 patients (7%) had a superimposed polyneuropathy. Of these 54 patients, 7 (13%) had clinical symptoms of their neuropathy. CONCLUSIONS: Coexistent focal or generalized neuropathies in ALS are not uncommon. Careful attention to these abnormalities may decrease morbidity in these patients.

Adult↗
PubMed1995

Comparison of the flexed and extended elbow positions in localizing ulnar neuropathy at the elbow.

Electrophysiologic localization of ulnar neuropathy at the elbow often depends on demonstration of segmental slowing. Based on normative data obtained from 50 control subjects, we compared the utility of flexed and extended elbow positions in demonstrating focal slowing at the elbow as compared to the forearm segment in patients with ulnar neuropathy. We studied 35 patients with ulnar neuropathy with definite electrophysiologic localization to the elbow segment defined by conduction block across the elbow segment or by focal slowing demonstrated either in the flexed or extended position. Applying cutoff values from the control group, all 35 patients demonstrated focal slowing at the elbow in the flexed position, whereas only 5 of 35 (14%) patients did so in the extended position. We conclude that the flexed elbow position is more sensitive than the extended position in localizing ulnar neuropathy at the elbow and should be the preferred method when performing ulnar motor conduction studies.

Adult↗
PubMed1995

Comparison of digital sensory studies in patients with carpal tunnel syndrome.

Electrodiagnosis of carpal tunnel syndrome (CTS) often depends on the demonstration of focal slowing of median sensory fibers across the wrist. We compared the relative sensitivity of the four median innervated digits in demonstrating focal slowing in patients with CTS. Antidromic sensory studies of digits 1, 2, 3, and 4 were performed on 30 control subjects to develop normative data. Fifty-nine consecutive patients with CTS were then studied to determine the sensitivity of focal slowing of each median innervated digit. In the 26 CTS patients with a normal distal motor latency (DML) to abductor pollicis brevis, digit 1 was abnormal in 81%, digit 2 in 42%, digit 3 in 54%, and digit 4 in 38%. In the 33 CTS patients with a prolonged DML, digit 1 was abnormal in 94%, digit 2 in 88%, digit 3 in 91%, and digit 4 in 88%. We conclude that in milder cases of CTS with a normal DML, digit 1 is the most sensitive in identifying focal slowing of sensory conduction across the wrist. However, in patients with a prolonged DML, the sensitivity of sensory conduction is not significantly different among the four digits.

Action Potentials↗
PubMed1995

Electrophysiological and urodynamic studies to monitor surgical outcome in children with tethered spinal cords.

Children with myelodysplasia often develop tethering of their spinal cord within 2-3 years after correction of their initial birth defect, leading to either neurological or urological dysfunction. Surveillance of these children includes electrophysiologic/urodynamic (EMG/UDS) studies to monitor improvement or deterioration of their neurological function. We reviewed 39 patients who underwent surgical untethering from 1979 to 1994 to determine whether postoperative EMG/UDS studies were useful in assessing outcome after surgery. All patients had a complete neurologic examination and an EMG/UDS prior to and 3 months after surgery. Twenty patients (51%) showed improvement in their EMG/UDS study after untethering, 15 (39%) demonstrated no significant change, and 4 (10%) showed deterioration. Improvement consisted of either return of previously absent motor units, return of sacral reflexes, or improved bladder dynamics. In a further 3 patients, subsequent deterioration on serial postoperative EMG/UDS testing was the first indication of recurrent tethering. We conclude that serial EMG/UDS evaluation in patients at risk for tethering of the spinal cord may serve as a useful adjunct to close clinical observation.

Child↗
PubMed1995

Electromyography: do the diagnostic ends justify the means?

BACKGROUND: Physicians are sometimes reluctant to refer patients for electrodiagnostic studies (electromyography with nerve conduction studies [EMG/NCS]) believing the test is too painful and of little benefit. METHODS: We performed two separate surveys on 126 and 100 consecutive patients referred to our laboratory to determine if EMG/NCS was beneficial to the referring physician and to compare the level of anxiety experienced by patients before the study with the pain actually experienced during the study. RESULTS: The electrodiagnosis was discordant from the referring diagnosis in 39% of the patients with an abnormal EMG/NCS. Pretest anxiety levels were low in 59% of the patients, medium in 27%, and high in 14%. After the tests, 82% of the patients said that the test was not as bad as expected, and was generally only mildly painful. Ninety-three responded that they would have the test performed again. CONCLUSIONS: EMG/NCS often suggest alternative diagnoses, and the actual pain experienced during an EMG/NCS study is significantly less than expected.

Adult↗
PubMed1995

Neurophysiologic assessment of urinary dysfunction in children with thoracic syringomyelia.

Isolated syringomyelia of the thoracic portion of the spinal cord is relatively uncommon. In children, signs and symptoms may involve only the urinary system. Five children who presented for evaluation of urinary tract dysfunction were found to have syringomyelia of the thoracic cord not associated with any other central nervous system abnormality on radiographic imaging. Each child underwent a complete neurologic examination and a complete electrophysiologic/urodynamic evaluation. One patient underwent surgical drainage of the syrinx due to progression of neurologic deficit, with slight improvement; three patients were treated pharmacologically to control the urinary dysfunction.

Child↗