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Biomedical subjects

W F Brown

Publications and source records attributed to W F Brown.

At least 73 records · Page 4Linked to original sources
PubMed1990

X-linked dominant hereditary motor and sensory neuropathy.

Modern techniques have defined the hereditary motor and sensory neuropathies (HMSN) as a genetically heterogeneous group of disorders. This includes a rare variant with X-linked dominant inheritance. We have traced this disorder through 6 generations of a large Canadian kindred; neurological and electrophysiological examinations were performed in 57 family members and nerve biopsies were studied in 2 affected males, early and late in the disease; 42/83 family members were affected. No male-to-male transmission was encountered in 19 sons of affected fathers, whereas all their daughters expressed the disease. Linkage was shown to the DNA loci DXYS1 Z max = 2.87 at theta max = 0.06 and to PGK1 Z max = 1.51 at theta max = 0 (Beckett et al., 1986). The typical clinical features are onset in early childhood, pes cavus, atrophy and weakness of peroneal muscles and intrinsic hand muscles, and sensory abnormalities. Males were severely affected, whereas females had mild or subclinical disease. Electrophysiological observations indicated a substantial loss of distal motor and sensory nerve fibres. Evoked compound muscle action potentials in extensor digitorum brevis were absent or severely reduced in 42% of cases and the peroneal motor nerve conduction velocity was mildly reduced to a mean 36.5 +/- 7.4 m.s-1. Sural sensory nerve action potentials were absent or severely reduced in 75% of those affected. Nerve biopsies showed loss of myelinated and unmyelinated nerve fibres, regenerative sprouting and secondary demyelination. The findings indicate that this distinct variant of HMSN is the result of primary axonal degeneration.

Adolescent↗
PubMed1990

Denervation in hemiplegic muscles.

This study examined the frequency of denervation activity in hemiplegic muscles in relation to the size and location of the central lesion. We studied 20 patients, 14 with major unilateral cerebral infarctions in the middle cerebral or internal carotid territories; four with a single lacune in the pons, internal capsule, or thalamus; and two with precentral infarcts. Using somatosensory evoked potentials, motor conduction studies, and assessments of conduction across the plexus and roots, we detected no conduction abnormalities on the affected side. Fibrillation was common in both groups, especially in distal and intermediate muscles. The distribution of the fibrillation and the normal conduction studies suggested that trauma of peripheral nerves was not a factor. Although the normal conduction studies and pattern of fibrillation activity do not exclude peripheral nerve trauma as the cause of the fibrillation, we suggest that transsynaptic degeneration is a reasonable alternative explanation.

Action Potentials↗
PubMed1990

Peripheral nerve injuries in cardiac anaesthesia.

Clinical nerve damage in patients undergoing CABG is frequent (15% of patients), while subclinical changes in ulnar nerve function are more common (40% here). Not all injuries develop in the early perioperative period. Most injuries are located at the elbow, and most recover without sequelae. Larger patients appear to be at most risk, but this study does not identify specific interventions which might decrease the risk of injury.

Anesthesia, General↗
PubMed1988

Motor unit estimates in the biceps-brachialis in amyotrophic lateral sclerosis.

A newly developed technique for estimating the number of motor units in the biceps-brachialis muscles and for studying the innervation patterns of motor units in the same muscles has been applied to the study of 17 patients with amyotrophic lateral sclerosis (ALS). Although severe motor unit losses were seen in many ALS cases, in most there were clear indications of increases in innervation densities, linked potentials, and blocking. This technique provides a powerful new tool for quantitatively assessing the extent of motor unit losses and the accompanying changes in innervation patterns in ALS.

Adult↗
PubMed1988

Methods for estimating numbers of motor units in biceps-brachialis muscles and losses of motor units with aging.

This paper presents a new method, here applied to the biceps-brachialis muscles, for estimating motor unit numbers in healthy subjects. This method combines isometric contraction, intramuscular needle electrode recordings, and spike-triggered averaging techniques to measure the sizes of motor unit potentials as recorded in the innervation zone with surface electrodes. The number of motor units is then estimated by division of the maximum biceps-brachialis "M" potential recorded with the same surface electrodes and evoked by supramaximal stimulation of the musculocutaneous nerve, by the mean of at least 10 surface-recorded motor unit potentials. The requisite intramuscular recordings provide additional information as to innervation density, incidence of linked potentials, and impulse blocking, phenomena that are particularly common in neurogenic and myogenic disorders. There was clear evidence of losses of motor units in older subjects: subjects over 60 years of age having approximately half the numbers of motor units of subjects under 60 years of age.

Adult↗
PubMed1988

An unusual subacute progressive motor neuronopathy with myasthenia-like features.

The initial presentation and clinical course of this 60-year old woman suggested a diagnosis of myasthenia gravis. The subsequent development of tongue fasciculations and the lack of response to treatment made a diagnosis of amyotrophic lateral sclerosis (ALS) more likely despite the presence of conjugate gaze paresis and the absence of many of the typical clinical and electromyographic (EMG) findings seen in this condition. The pathological findings were consistent with either a motor neuronopathy or an unusual variant of ALS. We review the clinical and pathological features of this unusual case in this report.

Amyotrophic Lateral Sclerosis↗
PubMed1988

Myopathy in primary systemic amyloidosis.

Involvement of the peripheral nervous system by amyloidosis is common. It is less well recognized that amyloid can directly infiltrate and weaken skeletal muscle. We report a case of a 73-year-old woman, known to have cardiac amyloidosis, who developed profound weakness secondary to amyloid myopathy. Review of the 8 other well documented cases in the literature has revealed a rather homogeneous syndrome. Proximal weakness, muscle stiffness, pseudohypertrophy and myalgia constitute the principal features. This syndrome usually develops in cases with well recognized generalized amyloidosis. Amyloid is deposited within the basal lamina of blood vessels and muscle fibers.

Aged↗
PubMed1987

Hand wasting due to mid-cervical spinal cord compression.

Three patients presented with hand wasting and weakness secondary to mid-cervical spinal cord compression. This was due to cervical spondylosis in two patients and a meningioma in one case. This phenomenon is probably similar to that seen with foramen magnum lesions and may be due to spinal cord ischemia distal to the compression, secondary to venous stasis.

Adult↗
PubMed1986

An acute axonal form of Guillain-Barré polyneuropathy.

Five patients with a clinical diagnosis of acute Guillain-Barré polyneuropathy (GBP) had electrically inexcitable motor nerves. All were quadriplegic. One patient died and 3 of the 4 survivors showed poor recovery. Autopsy studies on the patient who died showed severe axonal degeneration in nerve roots and distal nerves without inflammation or demyelination. Electrophysiological studies in these patients suggested that the predominant process was axonal degeneration. These cases may represent a separate clinicopathological entity, and constitute a variant of GBP characterized by an acute axonal neuropathy.

Acute Disease↗
PubMed1986

C7 radiculopathy: importance of scapular winging in clinical diagnosis.

Lesions of the seventh cervical (C7) root are common and cause a readily recognised neurological syndrome. Recognition of this pattern is essential in differentiating C7 root lesions from lesions of the brachial plexus or peripheral nerves. Serratus anterior weakness is not generally included in this syndrome. We report six verified cases of C7 radiculopathy in which weakness of the serratus anterior was present in addition to the usual findings. This was manifest as winging of the scapula, when pushing forward against a wall, either with the hands at shoulder level or, in some cases, only when the hands were lowered to waist level. This latter method of testing places the muscle at a mechanical disadvantage and reveals partial paralysis. Analysis of this clinical finding complements anatomical evidence suggesting that the powerful lower digitations of the muscle may be primarily supplied by the C7 root in some cases. Scapular winging, apparent either in the usual position or the modified position described here, should be recognised as consistent with a diagnosis of C7 radiculopathy. When present, this sign serves to differentiate C7 radiculopathy from lesions of the brachial plexus or radial nerve.

Adult↗
PubMed1985

The pathological basis of conduction block in human neuropathies.

Conduction block was detected in patients with neuropathy by measuring a decrease in the size of the compound muscle action potential of more than 20% on proximal versus distal stimulation of the peroneal, median or ulnar nerve in the absence of excess temporal dispersion of the potential. The teased fibre analyses of nerve biopsies from four patients with "definite" and six patients with "probable" conduction block and from seven patients with neuropathy but without conduction block were compared. All patients with conduction block had significant demyelination (X% demyelinated and remyelinated fibres = 50%) while those without conduction block did not (X = 5.0%). Demyelination is the pathological basis of conduction block in human neuropathies.

Adult↗
PubMed1984

Application of a computerized medical decision-making process to the problem of digoxin intoxication.

A computerized medical decision-making system was used to monitor signs and predisposing factors of digoxin intoxication in patients receiving digoxin. This process automatically reviewed the patient's data base nightly for drug interactions, laboratory data and electrocardiographic findings with known association with digoxin intoxication. These decisions were formated into a "digoxin alert report" and sent to line printers in the nursing division to be placed on the individual patients' charts. To assess the effect of these reports on patient management, a randomized double-blind study was undertaken. Patients were assigned to an alert or nonalert group. Alert reports were withheld from charts of patients in the nonalert group. A medical record review was subsequently carried out, wherein the physician's orders were searched to identify actions taken with possible relation to the digoxin alerts. The computer monitored 396 patients over a 3 month period. Of these, 211 (53%) were randomized to the alert group and 185 (47%) to the nonalert group. Seventy-two percent of patients received at least one alert. The most frequently occurring alerts included: hypoxemia, hypokalemia, concurrent use of a beta-adrenergic blocking agent, renal insufficiency and ventricular arrhythmia. Results from the record review demonstrated a 22% increase in physician actions for the alert group. Specifically, patients in the alert group were 2.7 times more likely to have a serum digoxin determination ordered and 2.8 times more likely to have digoxin withheld on the day of a digoxin alert than were patients in the nonalert group.

Aged↗
PubMed1984

Conduction block and denervation in Guillain-Barré polyneuropathy.

The two main electrophysiological abnormalities seen in the first two weeks of the acute Guillain-Barré syndrome (GBS) were conduction block and, in some patients, low maximum M response amplitudes. In this study period, maximum motor and sensory conduction velocities were often in the normal range and temporal dispersion was relatively less common. The conduction block was generalized in its distribution in some peripheral nerves, while in others the block was predominantly proximal or distal in location. Conduction abnormalities in excess of those proximal or distal to it were frequent at common sites of entrapment. Very low M response amplitudes early in the course of the disease correlated well with the subsequent development and frequency of denervation in the muscle(s) and unfavourable clinical recovery. We conclude that conduction block is the main cause of the acute paralysis and sensory loss in the GBS. Axonal degeneration contributes variably to the acute disorder, but is the main cause of lasting disability.

Adult↗
PubMed1984

Sensory evoked potentials in Guillain-Barré polyneuropathy.

In 11 patients with acute Guillain-Barré polyneuropathy examined within 2 weeks of the onset of the paralysis, sensory evoked potential techniques were able to demonstrate a proximal conduction delay between Erb's point and the cervical cord in 10 subjects; while sensory conduction distal to Erb's point was much more commonly normal in the early period. Sensory evoked potential techniques provide therefore a valuable way to demonstrate proximal conduction velocity slowing early in the course of this disease.

Brachial Plexus↗