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Biomedical subjects

E L Logigian

Publications and source records attributed to E L Logigian.

At least 37 records · Page 2Linked to original sources
PubMed1998

Identification of a T cell subset capable of both IFN-gamma and IL-10 secretion in patients with chronic Borrelia burgdorferi infection.

A novel population of both IFN-gamma- and IL-10-secreting human T cells that differentiate in the presence of exogenous IL-12 in vitro has recently been described. Whether this T cell population exists in vivo is unknown. Borrelia burgdorferi, the etiologic agent of Lyme disease, can induce a chronic infection in the presence of a vigorous humoral immune response. We established T cell lines specific for B. burgdorferi and tetanus toxoid from subjects with chronic B. burgdorferi infection and healthy controls in limiting dilution experiments and assessed proliferation and cytokine secretion. As expected, higher frequencies of B. burgdorferi-specific precursor T cells were observed in Lyme patients compared with controls. In both groups of subjects, T cell lines specific for B. burgdorferi secreted high amounts of IFN-gamma. However, in patients with Lyme disease, 27% of T cell lines secreted not only IFN-gamma but also IL-10, which was only observed in 0.6% of B. burgdorferi-reactive T cell lines generated from controls and in none of the tetanus toxoid-reactive T cell lines generated from either Lyme patients and controls. Single cell PHA cloning confirmed that both cytokines were secreted from one clonally expanded precursor cell. Whole mononuclear cells from B. burgdorferi-infected individuals, but not from controls, secreted IL-12. Moreover, neutralizing anti-IL-12 mAbs inhibited the generation of the IFN-gamma/IL-10 population. These data demonstrate that this novel population of IL-12-induced IFN-gamma/IL-10-secreting T cells is generated in response to chronic B. burgdorferi infection.

Adult↗
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

Electrodiagnostic studies: are they useful in clinical practice?

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.

Adolescent↗
PubMed1998

Short-segment incremental studies to localize ulnar nerve entrapment at the wrist.

Precise electrophysiologic localization of ulnar neuropathy at the wrist (UNW) is often problematic. In the last year, we evaluated only two patients who presented clinically with UNW. Routine electrophysiologic techniques were nondiagnostic for UNW. In contrast, short-segment incremental studies (SSIS) across the wrist demonstrated conduction block and segmental slowing of nerve conduction across the wrist in both patients. We conclude that SSIS is a valuable tool for diagnosis, precise localization, and prognosis of UNW.

Adult↗
PubMed1998

Root stimulation studies in the evaluation of patients with motor neuron disease.

Nerve root stimulation may be employed in patients with motor neuron disease (MND) to rule out motor neuropathy with conduction block. The diagnostic utility of these studies is unknown, in part because the range of amplitude changes across nerve root segments in patients with active neuronal degeneration has not been well studied. We reviewed root stimulation studies in 32 patients (59 nerves) with MND and found segmental amplitude reduction from 0 to 45%, a range similar to values reported for normal subjects; there was no suggestion of conduction block based on our usual criteria.

Adult↗
PubMed1998

Effect of agonist load on fastest muscle contractions in human elbow flexors.

The purpose of this study was to investigate whether the central nervous system (CNS) motor program subserving most-rapid voluntary force pulse generation is modified according to the level of agonist muscle load maintained prior to the pulse. Five normal subjects produced most-rapid force pulses to a target of 20% maximum voluntary force (MVF) above different levels of steady tonic contraction. Time to reach peak force, the first agonist burst duration and area were relatively constant for loads up to approximately 40% of MVF and then increased substantially with larger loads. These results indicate that the CNS adjusts agonist burst amplitude and duration in order to accomplish the same rapid motor task depending on the load. It is argued that these adjustments are necessary to compensate for physiological limitations of motor unit behavior and non-linearity between EMG activity and phasic force output.

Adult↗
PubMed1998

The mixed nerve silent period in normal subjects and patients with amyotrophic lateral sclerosis.

The mixed nerve silent period (MNSP) is the period of motor inhibition observed when the mixed nerve innervating a voluntary activated muscle is electrically stimulated. The etiology of the MNSP is multifactorial, with the early and middle phases likely to be related to the effects of antidromic motor nerve activity on peripheral nerve and spinal interneurons. The terminal portion of the MNSP is mediated primarily by small diameter myelinated afferent fibers. The duration and latency of the MNSP vary as a function of both strength of stimulation and level of voluntary activation. In this study, we varied both stimulus strength and exertion, and compared MNSPs in 6 normal subjects with those obtained from 8 patients with amyotrophic lateral sclerosis (ALS). Differences between patients and control subjects included a longer duration of the MNSP in ALS patients, as well as less complete inhibition in the middle phases of the period. The longer duration of the MNSP may reflect an abnormality of sensory motor processing in ALS patients. The physiology underlying the incomplete inhibition is unclear, but may reflect abnormalities in Renshaw cell function.

Adult↗
PubMed1997

Treatment of occupational cramp with botulinum toxin: diffusion of toxin to adjacent noninjected muscles.

Over a 5-year period, 40 patients, 11 with musician's and 29 with writer's cramp, were treated with botulinum toxin A using a precise injection technique in which the hollow-bore electromyography (EMG) needle was positioned by both standard EMG and by muscle twitch evoked by stimulating current passed through it. Moderate to complete improvement in dystonia occurred in 28 patients (70%) after the first injection and in 34 patients (85%) after the second injection with better outcome in nonmusicians than in musicians. Of note, weakness of uninjected muscles, immediately adjacent to those injected, was found in 25/40 patients (63%). The most common patterns of toxin spread were from flexor digitorum sublimis to profundus, extensor carpi radialis to extensor digitorum communis, and extensor indicis proprius to extensor pollicis brevis. Spread to, and weakness of, adjacent uninjected muscles was a major factor contributing to suboptimal outcome in 6/39 (15%) such patients.

Adult↗
PubMed1997

Peripheral nervous system Lyme borreliosis.

There are acute and chronic Lyme neuropathies. The seasonal acute syndromes of cranial neuritis or radiculoneuritis are generally quite distinctive, but may cause diagnostic difficulty when one syndrome occurs without the other, when erythema migrans is absent or missed, and when meningeal signs are minimal or absent. The chronic Lyme radiculoneuropathies are less severe, and less distinctive. Their recognition depends on eliciting a history of earlier classical manifestations of Lyme disease and by laboratory testing. In both acute and chronic Lyme radiculoneuropathy, electrophysiologic testing often proves the presence of a sensorimotor, axon loss polyradiculoneuropathy. Both acute and chronic Lyme radiculoneuropathy have similar pathologic features and can be classified as a nonvasculitic mononeuritis multiplex. The pathogenesis is uncertain; both direct infection as well as parainfectious mechanisms may play a role. The treatment with which we have the most experience is intravenous ceftriaxone 2 g/day for 2 to 4 weeks. Improvement occurs rapidly over days to weeks in early Lyme neuroborreliosis, but slowly over many months in chronic neuroborreliosis.

Adult↗
PubMed1997

A case of Hodgkin's lymphoma producing neuromyotonia.

The syndrome of neuromyotonia produces muscle stiffness, cramps, and frequently, excessive sweating. Most cases are idiopathic, but some are associated with neoplasms, especially immune cell cancers. Voltage-gated potassium channels may be the target of an autoantibody attack in idiopathic generalized neuromyotonia (Isaacs' syndrome). The cases associated with neoplasms may also have an autoimmune etiology. We report the first case of neuromyotonia as the presenting feature of Hodgkin's lymphoma and propose a paraneoplastic mechanism that would link the purported autoimmune etiology in Isaacs' syndrome with the cancer-associated cases.

Adult↗
PubMed1997

Reversible cerebral hypoperfusion in Lyme encephalopathy.

Lyme encephalopathy (LE) presents with subtle neuropsychiatric symptoms months to years after onset of infection with Borrelia burgdorferi. Brain magnetic resonance images are usually normal. We asked whether quantitative single photon emission computed tomography (SPECT) is a useful method to diagnose LE, to measure the response to antibiotic therapy, and to determine its neuroanatomic basis. In 13 patients with objective evidence of LE, SPECT demonstrated reduced cerebral perfusion (mean perfusion defect index [PDI] = 255), particularly in frontal subcortical and cortical regions. Six months after treatment with 1 month of intravenous ceftriaxone, perfusion significantly improved in all 13 patients (mean PDI = 188). In nine patients with neuropsychiatric symptoms following Lyme disease, but without objective abnormalities (e.g., possible LE), perfusion was similar to that of the treated LE group (mean PDI = 198); six possible LE patients (67%) had already received ceftriaxone prior to our evaluation. Perfusion was significantly lower in patients with LE and possible LE than in 26 normal subjects (mean PDI = 136), but 4 normal subjects (15%) had low perfusion in the LE range. We conclude that LE patients have hypoperfusion of frontal subcortical and cortical structures that is partially reversed after ceftriaxone therapy. However, SPECT cannot be used alone to diagnose LE or determine the presence of active CNS infection.

Adult↗
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

The critical importance of stimulus intensity in intraoperative monitoring for partial dorsal rhizotomy.

During partial lumbosacral dorsal rhizotomy (PDR), intraoperative dorsal rootlet stimulation (drs) evokes motor responses, presumed to be reflexes, which are used to select rootlets for section. However, dr stimuli may also costimulate ventral root (vr) and evoke an M rather than a reflex response, the two being distinguishable only by comparison of response latencies after drs at two separate sites. In 15 consecutive spastic cerebral palsy patients undergoing PDR, we asked whether reflex and M responses were distinguishable on the basis of stimulus intensity (SI). For soleus H reflexes evoked by percutaneous tibial nerve stimulation, the SI for reflex afferents was usually subthreshold for exciting motor fibers. Similarly, for nerve roots, reflexes were evoked by drs at SIs generally less than that for M responses evoked by vr stimulation (vrs). In contrast, M responses evoked by drs required SIs that were on average 20 times greater. Finally, costimulation of contralateral vr after ipsilateral vrs occurred at SIs shown to evoke M responses after drs. We conclude that: (1) reflex and M responses evoked by drs are distinguishable on the basis of the required SI; and (2) drs employing SIs greater than required for vrs evokes M rather than reflex responses due to costimulation of ipsilateral and contralateral vr.

Cerebral Palsy↗
PubMed1996

Proximally evoked soleus H reflexes in the evaluation of axonal neuropathy.

It is sometimes difficult to differentiate physiologically distal axonopathy from proximal root or nerve disease. Standard soleus H reflexes evoked by distal tibial nerve stimulation at the popliteal fossa are often absent in both syndromes. In this study we distinguish the two by the presence or absence of soleus H reflexes evoked by proximal sciatic nerve stimulation at the gluteal fold. In 12 normal subjects maximum H reflex amplitudes evoked by distal tibial and proximal sciatic stimulation were essentially equal. In 12 patients with suspected distal polyneuropathy, proximal but not distal stimulation evoked H reflexes. By contrast, in 10 patients with lumbosacral root or proximal nerve disease, both proximal and distal stimulation failed to elicit H reflexes. In 2 patients with lower motor neuronopathy, low but comparable amplitude H reflexes were evoked at both sites. We conclude that the presence of a proximally evoked soleus H reflex may provide specific evidence of distal axonopathy when standard soleus H reflexes are absent.

Adult↗
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↗