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Biomedical subjects

R E Lovelace

Publications and source records attributed to R E Lovelace.

At least 37 records · Page 2Linked to original sources
PubMed1991

Chronic inflammatory demyelinating polyneuropathy in childhood: clinical and electrophysiological features.

Five children with chronic progressive polyneuropathy but no familial history of it showed electrophysiological evidence of demyelination with partial conduction block, temporal dispersion, and focal slowing of nerve conduction velocities in multiple nerves. These findings are indicative of an acquired demyelinating polyneuropathy that is chronic and inflammatory and differentiate this condition from most of the inherited neuropathies. It is very important to recognize this entity because of the availability of various treatments.

Child↗
PubMed1991

Becker muscular dystrophy or spinal muscular atrophy?--Dystrophin studies resolve conflicting results of electromyography and muscle biopsy.

We studied a 29-year-old man with slowly progressive proximal leg weakness, calf hypertrophy, and high serum levels of creatine kinase activity. Clinically, it was not possible to identify his as a sporadic instance of Becker muscular dystrophy (BMD) or one of spinal muscular atrophy. The problem arose because electromyography and elevated creatine kinase suggested a myopathy whereas changes in the muscle biopsy resembled a neurogenic disorder. The diagnosis of BMD was made by DNA analysis which detected a deletion at Xp21 and by immunoelectrophoresis and immunohistochemical tests that identified an abnormal form of gene product, dystrophin. These studies were important for genetic counselling, identifying an X-linked disease instead of one that is autosomal recessive.

Adult↗
PubMed1990

X-linked spinal muscular atrophy (Kennedy's syndrome). A kindred with hypobetalipoproteinemia.

Kennedy's syndrome, X-linked adult-onset bulbospinal muscular atrophy, has been described in over 30 families. The characteristic distribution of weakness creates a recognizable syndrome, augmented by frequent findings of testicular atrophy and gynecomastia. Type IV or type II hyperlipoproteinemia has been found in some families. We have studied another family with Kennedy's syndrome, this one with hypobetalipoproteinemia. The diversity of serum patterns suggests that lipoprotein abnormalities are not causally related to either the endocrinopathy or the spinal muscular atrophy. However, gene linkage studies indicate proximity of the gene for Kennedy's syndrome and the gene encoding the androgen receptor, which could explain the combination of a motor neuron disorder and the endocrine abnormalities.

Adult↗
PubMed1990

Long-duration polyphasic motor unit potentials in myopathies: a quantitative study with pathological correlation.

In most myopathies, the duration of motor unit action potentials (MUAPs) is shorter than normal. However, polyphasic MUAPs of duration longer than 20% of the control mean, (long-duration polyphasic potentials, or LDPPs) may be seen. We therefore analyzed the incidence and meaning of LDPPs using quantitative MUAP analysis in 41 patients with different myopathies. The mean duration of all potentials was reduced in only 64% of patients because LDPPs increased the mean. When only simple potentials were considered, however, the mean duration was decreased in 95% of patients. This observation confirms the need to exclude LDPPs when calculating the mean duration of MUAPs for diagnosis. We found LDPPs most often in chronic polymyositis and in one patient with Becker Muscular Dystrophy. LDPPs are attributed to desynchronization of single-fiber potentials within the MUAP and may be due to slow conduction in regenerating muscle fibers.

Action Potentials↗
PubMed1990

Motor neuron disease and amyotrophic lateral sclerosis: relation of high CSF protein content to paraproteinemia and clinical syndromes.

From 1984 to 1988, 11 of 120 patients (9%) with motor neuron disease (MND) had paraproteins detected by serum immunofixation electrophoresis (IFE), compared with 4 (3%) by cellulose acetate gels: 1 patient had progressive spinal muscular atrophy, 5 patients had amyotrophic lateral sclerosis (ALS), and 5 patients had ALS with probable upper motor neuron signs. Four of 5 patients (80%) with cerebrospinal fluid (CSF) protein content above 75 mg/dl had paraproteins, as did 6 of 30 with values above 50 mg/dl. Four of 14 patients with cerebrospinal oligoclonal bands (OCB) also had paraproteins. Two patients with ALS, CSF protein content above 75 mg/dl, and paraproteinemia had lymphoma. We conclude the following about patients with MND: high CSF protein content (especially above 75 mg/dl) or CSF OCB makes paraproteinemia more likely; some of these patients may have lymphoma; there is an inordinately high occurrence of paraproteinemia in MND; and IFE on agarose is more sensitive than electrophoresis on cellulose acetate in detecting paraproteins. Syndromes of paraproteinemia and high CSF protein are not restricted to the lower motor neuron but qualify as "ALS" with coexisting upper motor neuron signs.

Adult↗
PubMed1989

Postpolio muscular atrophy. Diagnostic utility of macroelectromyography.

Muscles recovered from previous poliomyelitis may exhibit new weakness and wasting years after the original infection (postpolio muscular atrophy). Routine electrophysiological and morphological techniques may not differentiate weakening muscles from previously affected but stable muscles. We used quantitative motor unit potential analysis, single-fiber electromyography, and macroelectromyography (macro-EMG) to determine if these techniques could identify weakening muscles. We classified 18 previously affected muscles according to strength from 12 patients who had had poliomyelitis 18 to 50 years earlier. Muscles of normal strength had large-amplitude macro-EMG signals (1000 to 4110 microV; normal level, less than 390 microV). Muscles with new weakness and atrophy had smaller than expected macro-EMG amplitude (130 to 450 microV). Two muscles with weakness and atrophy unchanged since the original childhood infection had markedly increased macro-EMG amplitude (1710 and 1860 microV), suggesting the increased macro-EMG amplitude is due to stable reinnervation not strength. Mean motor unit potential duration and amplitude were lower in newly weakened muscles, but jitter, fiber density, and blocking were similar in all muscles regardless of strength. We conclude that low-amplitude macro-EMG signals may be useful in the identification of muscles weakened by postpolio muscular atrophy.

Adult↗
PubMed1989

Adductor laryngeal dystonia (spastic dysphonia): treatment with local injections of botulinum toxin (Botox).

Adductor spastic dysphonia (SD) is a laryngeal dystonia characterized by a choked, constrained voice pattern with breaks in vocal flow. Treatment with a variety of therapies including speech and pharmacotherapy have minimal benefit; only one-third of patients undergoing recurrent laryngeal nerve section have benefitted at 3 years. We have used local injections of botulinum toxin (Botox) bilaterally into vocalis muscles in 42 patients with SD. Injections were through a teflon-coated hollow electromyography (EMG) recording needle. Unilateral small doses (2.5-3.75 U) were of no clinical benefit. Bilateral small doses resulted in sustained improvement lasting 84.4 +/- 9.3 days. The degree of improvement was 61.1 +/- 4.6%. Common side-effects included a brief period of breathy hypophonia (8.5 +/- 2.5 days) and a mild sensation of choking/aspiration of fluids (1.7 +/- 0.6 days); there were no serious adverse effects. Vocal cord paralysis was not necessary for benefit. Follow-up vocalis muscle EMGs revealed denervation. All patients responded to retreatment (longest follow-up 3.5 years). Patients with prior recurrent laryngeal nerve surgery and residual uncomplicated dysphonia had similar results. Our results indicate that local injection of low-dose Botox is the treatment of choice for SD.

Adult↗
PubMed1989

Ring finger testing in carpal tunnel syndrome: a comparative study of diagnostic utility.

Because digit 4 (D4) has dual innervation, median and ulnar sensory latencies can be determined over identical distances. To determine if D4 testing is more sensitive than other commonly used techniques to diagnose carpal tunnel syndrome (CTS), we examined 42 hands with clinical evidence of carpal tunnel syndrome and 43 control hands. D4 latency was significantly longer than controls more often than digit 2 (D2) in patients with CTS. Comparing median to ulnar latencies from D4 was the most sensitive method to make the diagnosis of CTS. In mild CTS, a characteristic double peak potential was seen in recordings from the median nerve after stimulating D4. This potential provided immediate visual confirmation of the diagnosis of CTS. Comparing D4 latency along median and ulnar nerves is useful for detecting mild CTS and should be used whenever there are clinical signs and symptoms of CTS but electrodiagnostic studies are normal or borderline.

Adolescent↗
PubMed1989

Recurrent myoglobinuria and HIV seropositivity: incidental or pathogenic association?

There have been few cases of polymyositis in patients with AIDS, and polymyositis is rarely a cause of myoglobinuria. We studied a 20-year-old homosexual man with recurrent myoglobinuria. He was asymptomatic between episodes. Each episode was accompanied by muscle pain, limb weakness, high serum levels of creatine kinase, and pigmenturia. Muscle biopsy showed active necrosis without inflammation or abnormalities of glycolytic or other energy-generating enzymes. Antibodies to HIV were present in serum. Clinical evidence of AIDS has not developed in 2 years. Recurrent myoglobinuria may be another consequence of HIV infection.

Adult↗
PubMed1989

Neuromuscular involvement in mild, asymptomatic primary hyperparathyroidism.

PURPOSE: The classic neuromuscular abnormalities of primary hyperparathyroidism are based on observations from an earlier time when the disease presented commonly with signs and symptoms. The purpose of the present study was to test for neuromuscular abnormalities among patients currently seen with primary hyperparathyroidism, in whom the vast majority are asymptomatic. PATIENTS, METHODS, AND RESULTS: Forty-two patients (30 women, 12 men) were studied. Serum calcium level was 11.1 +/- 0.1 mg/dL (normal, 8.7 to 10.7 mg/dL); phosphorus level was 2.8 +/- 0.1 mg/dL (normal, 2.5 to 4.5 mg/dL). Parathyroid hormone levels by radioimmunoassay for N-terminal and for mid-molecule regions were 32.6 +/- 2.4 pg/mL (normal, 8 to 24 pg/mL) and 831 +/- 127 pg/mL (normal, 50 to 330 pg/mL), respectively. Although generalized weakness and easy fatigability were common complaints, they were not seen on neurologic examination. No patient showed typical neuromuscular findings such as muscle weakness or atrophy, hyperreflexia, abnormal gait, tongue fasciculations, or objective changes in mental status. On the other hand, paresthesias and muscle cramps were reported by 22 patients (52%). Neurologic examination in 12 patients (29%) demonstrated findings consisting of either stocking-glove loss of pain sensation or loss of vibratory sensation with diminished reflexes. Creatine phosphokinase levels were normal in all patients. Electromyography and nerve conduction studies were performed in nine patients. None showed myopathy or signs of motor unit denervation. Isolated nerve abnormalities (n = 6) and nonspecific sensory neuropathy (n = 2) were observed. CONCLUSION: We conclude that the classic neuromuscular syndrome of primary hyperparathyroidism is rarely seen among a typical modern-day group of patients with primary hyperparathyroidism. The results suggest that the neurologic component of primary hyperparathyroidism should be included among those features of the disease that have changed along with other aspects of the clinical profile of primary hyperparathyroidism.

Aged↗
PubMed1989

Electrophysiologic study of experimental demyelination induced by serum of patients with IgM M proteins and neuropathy.

We induced progressive conduction block in feline sciatic nerve by endoneurial injection of serum from 2 patients with demyelinating neuropathy and an anti-myelin-associated glycoprotein (MAG) IgM M protein. The block was longlasting (up to 4 days) and affected about half the motor nerve fibers. Control serum from patients with an IgM M protein that did not react with MAG produced a transient block (less than 48 hours) that affected an average of 25% of motor fibers. Nerves with sustained block showed widespread demyelination of many nerve fibers, exceeding controls. The findings support the view that chronic demyelinating neuropathy in these patients is caused by the anti-MAG M protein.

Animals↗
PubMed1988

Anomalous intrinsic hand muscle innervation in median and ulnar nerve lesions: an electrophysiological study.

A case with a median nerve lesion at the wrist without thenar atrophy and another with an ulnar nerve lesion at the elbow sparing the first dorsal interosseous are reported. Simultaneous multiple channel recording demonstrated in the first case a dual innervation of the abductor pollicis brevis by median and ulnar fibers via a Martin-Gruber anastomosis. In the second case, the cross over of the median fibers innervating the first dorsal interosseous was very proximal in the antecubital fossa. Stimulation at discrete points documented that the communicating fibers from the median joined the ulnar nerve 3 cm below the medial epicondyle.

Female↗
PubMed1988

The sympathetic skin response: normal values, elucidation of afferent components and application limits.

The sympathetic skin response (SSR), recorded at the hand and foot, was elicited using different classes of stimuli in 20 normal controls and 10 patients with peripheral neuropathy. We found that SSR latencies changed significantly with different recording sites, but not with different stimulation sites. Additionally, after ischemic conduction block of the arm in 3 normal controls, the previously obtainable SSR recorded at the hand became unobtainable with median nerve stimulation. Also, in one patient with subacute ganglionitis and 3 patients with demyelinating neuropathies, the SSR could not be elicited by electrical stimulation, but it could with deep inspiration. These results suggest that large diameter myelinated fibers may serve as afferents for the SSR. Furthermore, these findings imply that an unobtainable SSR by electrical stimulation may be due not only to dysfunction of the autonomic efferent nerve fibers, but also to abnormalities of the sensory afferents of the reflex. Therefore, investigations of autonomic dysfunction utilizing the SSR must be interpreted with caution in patients with peripheral neuropathies.

Acoustic Stimulation↗
PubMed1988

Comparative electrophysiologic evaluation of nerve grafts and autogenous vein grafts as nerve conduits: an experimental study.

This study was carried out to compare electrophysiologically the efficacy of autogenous vein grafts, with autogenous nerve grafts as conduits for nerve regeneration. A 0.75-cm segment of sciatic nerve was resected in two groups of Sprague-Dawley rats of equivalent maturity. The nerve gaps were bridged with an autogenous vein graft in the first group (31 rats), and an autogenous nerve graft in the second group (24 rats). Serial in vivo nerve conduction velocity studies and terminal in vitro nerve conduction velocity and nerve action potential measurements were performed. An additional group of 21 animals who had undergone no surgical procedures, were similarly studied to establish an age-adjusted baseline for comparison. Twelve animals in the first group, 14 in the second group, and 13 in the baseline group survived the full year of study. In vivo conduction velocities between the two experimental groups compared favorably. Nerve conduction velocity determined by in vitro technique confirmed this finding and measured similarly at about 78 percent of the baseline. Nerve action potential amplitude in the vein-grafted group was 12.0 percent of the baseline, while the nerve-grafted group was 23.9 percent of the baseline. This study demonstrated that the vein graft compares well with the nerve graft in nerve conduction velocity, but only one-half as well in nerve action potential.

Action Potentials↗
PubMed1988

Seronegative myasthenia gravis.

Of 221 patients with myasthenia gravis, 18.5% had no detectable antibodies to acetylcholine receptor. Seven of 14 patients (50%) with only ocular symptoms for more than 2 years were seronegative, and 25 of 145 (17%) patients with generalized myasthenia were seronegative. The clinical characteristics of seronegative patients did not differ from patients with high antibody titers. No seronegative patient had a thymoma, but that difference did not reach statistical significance. Lack of serum antibodies did not preclude favorable response to thymectomy or plasmapheresis.

Adult↗
PubMed1988

Localized injections of botulinum toxin for the treatment of focal laryngeal dystonia (spastic dysphonia).

Spastic dysphonia is a condition producing a strain-strangle phonation. We have previously classified most of these patients as having focal laryngeal dystonia, a disorder of central motor processing. The initial success of recurrent nerve section in many of these patients has been followed by recurrence of symptoms in months to years. Bilateral involvement of the vocal cords with hyperfunction of the nonparalyzed vocal cord could explain these failures. Injection of botulinum toxin (BOTOX) has been effective treatment for many focal dystonias. We have treated more than 100 patients with dystonia including five with laryngeal dystonia. All of the patients laryngeal had dramatic improvement after 48 to 72 hours; benefit lasted 3 to 9 months for each injection period. BOTOX injection can be performed on awake, ambulatory patients. Bilateral treatment and titration of dose can achieve the desired degree of weakness.

Adult↗
PubMed1988

Clinical and laboratory characteristics of focal laryngeal dystonia: study of 110 cases.

Spastic dysphonia is a syndrome often producing a strain-strangle voice. We have previously classified most of these patients as having focal laryngeal dystonia, a disorder of central motor processing. In a study of 1,280 cases of dystonia registered at the Dystonia Clinical Research Center at the Columbia-Presbyterian Medical Center, we found 110 patients who had vocal cord involvement. These patients had historical information evaluated for age of onset (mean 34.6 years), duration of symptoms (mean 13.8 years), sex (1.4:1 female to male) family history (positive in 23%), and primary (66%) and secondary (34%) etiology; neurological evaluation for other dystonic involvement (25% with segmental cranial involvement, 23% with generalized dystonia) or tremor (irregular 23%, regular 6% on EMG). Treatment options were evaluated and included speech therapy, psychotherapy, biofeedback (with limited success), systemic medication (limited success except in abductor cases), nerve section (with late failure rate), and the use of botulinum toxin (improvement in all 34 injected patients).

Adult↗