Biomedical subjects

L Krain

Publications and source records attributed to L Krain.

4 recordsLinked to original sources

PubMed1992

Normal conduction in pathways traversing an asymptomatic multiple sclerosis plaque.

A 31-year-old woman developed right facial myokymia as the initial manifestation of multiple sclerosis (MS). An MRI scan revealed a focal signal abnormality confined to the left dorsolateral pontomedullary region. Brain-stem auditory evoked potentials (BAEPs), somatosensory evoked potentials (SEPs), and blink reflex (BR) failed to show a conduction abnormality through the left brain-stem lesion. Instead, BAEP and BR indicated a conduction defect in the right pons and EMG showed myokymic discharges in right facial muscles. Our findings provide rare documentation of normal conduction through a presumably asymptomatic MS plaque. The abnormal MRI signal likely represents tissue edema, rather than demyelination. This case demonstrates that physical findings in MS patients may correlate better with electrophysiological abnormalities than with MRI abnormalities.

Adult↗

PubMed1991

Magnetic stimulation: examination of motor function in patients with cervical spine or cord lesion.

In 20 patients with cervical spine or cord lesions, we examined motor evoked potentials (MEPs) by transcranially applied magnetic stimulation to the motor cortex. We used a large-diameter (12 cm) coil to induce equal current in both left and right hemispheres. The MEPs were recorded simultaneously from multiple muscles covering the C5 to C8 myotome distribution bilaterally. The MEP abnormalities correlated well with clinical muscle weakness in 15 patients. In two patients, MEP revealed abnormalities in muscles of normal strength. Three patients with sensory but without motor deficit had normal MEPs. We conclude that magnetic stimulation is a useful adjunct in confirming and objectifying motor weakness, and in localizing the level of dysfunction in cervical spine lesions.

Adult↗

PubMed1990

Transcranial magnetic stimulation of the facial nerve: recording technique and estimation of the stimulated site.

We compared transcranial magnetic and conventional electrical stimulation in 20 facial nerves of 10 normal subjects. A magnetic coil was placed tangentially over T5 or T6 (10-20 electroencephalogram electrode placement system) and electrical stimulation was applied 1 cm below the anterior tragus. Compound muscle action potentials recorded from the ipsilateral nasalis muscle showed onset latencies (mean +/- SD) of 4.48 +/- 0.50 ms with magnetic stimulation and 3.15 +/- 0.40 ms with electrical stimulation, a mean difference of 1.33 +/- 0.14 ms. Stimulation of the extracranial facial nerve at two sites yielded a conduction velocity of 59.6 +/- 4.5 m/s. Based on these findings, the magnetically stimulated site was estimated to fall 79.0 +/- 8.6 mm proximal to the point of electrical stimulation. Taking the average length of the nerve trunk and histological specificity of the root exit zone into consideration, evidence indicates that the root exit zone of the facial nerve is the most likely initiating site of excitation with magnetic stimulation.

Action Potentials↗

PubMed1975

Dermatomyositis in six patients without initial muscle involvement.

Six patients initially had the characteristic skin eruption of dermatomyositis but no other evidence of the disease. They all later developed dermatomyositis. The clinical, laboratory, and pathological data suggest that whereas polymyositis may occur without skin involvement, the cutaneous features od dermatomyositis may be seen in the absence of detectable muscle disease. This variant of dermatomyositis occurs in children and adults but has not been found to be associated with internal malignant disease. The persistence of skin lesions despite systemic corticosteroid therapy is a poor prognostic sign. There were two patients with pulmonary fibrosis and dermatomyositis in this group. The presence of pulmonary fibrosis can contribute to a delay in diagnosis of dermatomyositis. Patients with pulmonary fibrosis had a poorer prognosis, despite moderate dosages of corticosteroids.

Adolescent↗