Search PubMed⌕ Search

Biomedical subjects

D Dumitru

Publications and source records attributed to D Dumitru.

70 records · Page 4Linked to original sources
PubMed1988

Posterior femoral cutaneous nerve neuropathy and somatosensory evoked potentials.

Isolated posterior femoral cutaneous nerve (PFCN) entrapment has only rarely been described in the literature and never documented electrophysiologically. We report an unusual occurrence of such an injury and use somatosensory evoked potentials (SSEP) to explore the extent of the lesion. A 40-year-old woman had localized numbness of the right posterior thigh after a left putamenal hemorrhage four years before this study. She made a complete recovery from her stroke within four months; however, she continued to experience decreased sensation in the right posterior thigh. Normal sural and peroneal nerve latencies, velocities, and amplitudes were obtained in the right leg. Electromyographic examination of right leg and related para spinal musculature was unremarkable. SSEP were then performed with CZ'-FZ (10-20 system) electrode placement. Normal sural, lateral femoral cutaneous, and posterior tibial responses were obtained bilaterally. Response differences consistent with an isolated right PFCN neuropathy were observed. The perfectly symmetric SSEP responses for the sural, lateral femoral cutaneous, and posterior tibial nerves obviate a central, and substantiate a peripheral, cause for the altered right PFCN evoked response.

Adult↗
PubMed1988

Congenital hemihypertrophy associated with posterior interosseous nerve entrapment.

An entrapment of the posterior interosseous nerve (PIN) associated with congenital hemihypertrophy has not been reported previously. A 63-year-old man noted that since birth his right arm had been considerably larger than his left. Fifteen years before our initial examination, however, he first noted weakness of his right wrist and finger extensors without sensory loss. Physical examination revealed atrophy and weakness of the musculature innervated by the PIN distal to the supinator and the first dorsal interosseous (FDI). Sensation was intact throughout the entire right arm. Electromyographic examination demonstrated membrane instability and decreased activation of voluntary motor units in the radial nerve musculature distal to the supinator and in the FDI. Electrophysiologic evidence suggested an anomalous innervation of the FDI by the PIN. Surgical exploration revealed hypertrophy of the brachioradialis, extensor carpi radialis longus and brevis, and supinator muscles, with atrophy of all muscles distal to the supinator. The supinator muscle appeared to be constricting the PIN and was sectioned. Clinical and electrodiagnostic follow-up at six months and again at four years revealed no further deterioration.

Arm↗
PubMed1987

Brachial neuritis involving the bilateral phrenic nerves.

Brachial neuritis with bilateral hemidiaphragmatic paralysis has been reported in two previous cases in the literature. We report a patient who experienced severe right shoulder discomfort three weeks prior to hospital admission which evolved to include both shoulders. Two weeks prior to admission he noticed the onset of discomfort in breathing in the supine position and shortness of breath with minor exertion. The admitting diagnoses were myocardial infarction due to significant ECG changes and idiopathic elevated bilateral hemidiaphragms. The patient had findings significant for tachypnea, dyspnea, decreased breath sounds at the bases bilaterally, impaired motion of the bilateral lung bases on inspiration and paradoxical respirations. Comprehensive medical testing and evaluation revealed bilateral elevated hemidiaphragms and vital capacity 40% of normal. Weakness of the proximal shoulder girdle and bicep musculature bilaterally was noted. Electromyography was significant for reduced recruitment pattern in the bilateral shoulder girdle musculature. Nerve conduction studies suggested bilateral phrenic neuropathy. This case is an unusual presentation of brachial neuritis affecting the bilateral shoulder girdle with phrenic nerve involvement. The differential diagnosis of acute shoulder pain associated with respiratory symptomatology should therefore include brachial neuritis.

Brachial Plexus↗
PubMed1986

Cruciate paralysis. Case report.

A rare case of cruciate paralysis is reported in a 39-year-old man following a motor-vehicle accident. The differentiation of this syndrome from a central cervical spinal cord injury is delineated.

Adult↗
PubMedDate not supplied

Far-field potential production by quadrupole generators in cylindrical volume conductors.

Far-field potentials have been observed clinically and recognized as such for approximately 30 years. Unfortunately a complete understanding of far-field potential generation is not yet at hand. An attractive model is the representation of an action potential by a quadrupole consisting of a leading and trailing dipole with respect to the direction of propagation. This investigation physically models an action potential by using a quadrupole constant current source and substantiates the concept that an action potential as modeled by two dipoles back-to-back is capable of producing far-field potentials in cylindrical volume conductors. The 4 postulated mechanisms of generating far-field potentials are validated, i.e., an action potential encountering (1) different size volume conductors, (2) the termination of excitable tissue, (3) a change in conducting medium conductivity, and (4) a bend in the nerve. A fifth postulated but previously not demonstrated method of far-field production, neural branching, is shown by the quadrupole model to also be capable of yielding far-field potentials. The termination of a volume conductor is also shown to be capable of generating a voltage difference across the quadrupole. Any of the above 6 conditions create an alteration in the symmetry of the leading and trailing dipole moments resulting in a transient potential difference across the quadrupole as recorded with a far-field recording montage. The potential difference produced by the asymmetric electric field between the leading and trailing dipoles recorded distantly in areas of low potential gradient is the so-called far-field potential. This investigation substantiates the utility of the leading/trailing dipole model of far-field production and offers a simple model of passive voltage distributions secondary to dipolar moment imbalances to better understand the generation of far-field potentials in cylindrical volume conductors.

Brain↗
PubMedDate not supplied

Motor unit action potential duration recorded by monopolar and concentric needle electrodes. Physiologic implications.

Controversy exists regarding motor unit action potentials (MUAPs) recorded with monopolar v concentric needle electrodes. All investigations to date have used different instrumentation parameters combined with different motor unit potential populations to assess comparative durations for MUAPs. In this investigation, the same MUAP was analyzed for both monopolar and concentric needle electrodes with identical instrumentation parameters. Monopolar needle electrodes were found to record MUAPs with slightly longer durations, a result that reached statistical significance. Manual wideband high-resolution MUAP analysis demonstrated durations approaching 30 ms for both electrodes, which is different from the approximately 10 ms presently measured for both electrode types. A hypothesis was proposed whereby the total duration of current flow, which is directly proportional to muscle fiber length, is the primary determinant of MUAP duration. The physiologic implications of this hypothesis are discussed.

Action Potentials↗
PubMedDate not supplied

Fibrillation potential amplitude after denervation.

Fibrillation potentials have been reported to decline in amplitude with time after denervation. The use of maximum fibrillation potential amplitude to determine the relative acuity of axonal loss ("old" v "new/recurrent") has been advocated but with conflicting endorsements as to the appropriate benchmark amplitude, i.e., 100 microV compared with 250 microV. This investigation uses computer simulations to examine the rate of fibrillation potential amplitude decline expected given known values for muscle fiber size atrophy and conduction velocity slowing over time after denervation. Factors that affect the amplitude and potentially lead to erroneous interpretations in the clinical scenario of partially denervated muscle tissue are discussed. The use of fibrillation potential maximum amplitude criteria to determine the age of lesion onset in both totally and partially denervated muscle is fraught with technical and pathophysiological hazards of interpretation and must be considered cautiously, if at all, in clinical practice.

Animals↗
PubMedDate not supplied

The influence of compensation on recovery from low back pain.

The influence of financial compensation on recovery is one of the most controversial issues in the treatment of low back pain. In this review the authors include psychological aspects of compensation and the effects of compensation on injury rate, injury duration, and rehabilitation outcomes.

Back Pain↗
PubMedDate not supplied

Varied morphology of spontaneous single muscle fiber discharges.

Fibrillation potentials and positive sharp waves have rather stereotypical morphologies generally conforming to a triphasic initially positive and biphasic initially positive waveform, respectively. Careful attention during the needle electromyographic examination of muscle tissue with unstable resting membrane potentials, however, frequently reveals spontaneous potentials with appearances conforming to not only those described above but also waveforms with morphologies that can best be characterized as a blend of both a fibrillation potential and positive sharp wave. These "hybrid" or composite waveforms are hypothesized to arise from an electrical summation of two single muscle fibers repetitively discharging in a time-locked manner. Five individuals with lower motor neuron disorders displaying spontaneous discharges at rest during the needle electromyographic were examined. The spontaneous discharges were categorized according to their morphology. Stereotypical positive and negative onset fibrillation potentials and positive sharp waves from these patients were digitized. Computer simulations summating the digitized waveforms were successful in reproducing all of the observed "hybrid" waveforms documented in the patients. The supposition of two single muscle fibers discharging within a temporal domain conducive to electrical summation is an extension of the concept that electrical summation of muscle fibers comprising a motor unit summate to generate an electrical representation of that motor unit.

Adult↗