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Biomedical subjects

R R Young

Publications and source records attributed to R R Young.

At least 91 records · Page 5Linked to original sources
PubMed1979

Impact of CT on EEG.

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Electroencephalography↗
PubMed1979

Electrophysiologic analysis of the motor system after stroke: the "suppressive" effect of vibration.

The "suppressive" effect of vibration on the H-reflex was studied in 18 patients with motor system deficits due to cerebrovascular lesions of less than 3 weeks duration. No meaningful difference was found in the degree of H-reflex suppression between clinically involved and uninvolved sides in the patients, several of whom had increased deep tendon reflexes at the time of examination. It is concluded that hyperreflexia of "spasticity" cannot be explained purely on the basis of lack of presynaptic inhibition, even if it were one of the underlying mechanisms responsible for the suppression of the H-reflex by vibration, as previously claimed. Not only specific lesions themselves but also changes with the passage of time after CNS damage are important for understanding and treatment of motor system abnormalities.

Cerebrovascular Disorders↗
PubMed1978

Pattern shift visual evoked responses. Two hundred patients with optic neuritis and/or multiple sclerosis.

Fifty-one patients with clinically pure optic neuritis (ON) and 149 with possible, probable, or definite multiple sclerosis (MS) were tested with pattern shift visual evoked responses (PSVER) and compared with a group of 43 normal subjects. Attention was paid to response latency, intereye latency difference, as well as differences in amplitude or duration of the major positive peak (P100). Abnormal PSVER cannot be recorded from everyone with confirmed ON. Abnormal responses were recorded from 91% of all patients (including those with MS) who had a history of ON, 57% of all MS patients, and 36% of patients without a history of ON or an abnormal eye examination. Measurements of amplitude and duration proved to be of little value in this setting. Though abnormalities of PSVER are not "specific" for ON or MS, because they also result from other disease processes, they afford more reliable, quantitative documentation of abnormal conduction in visual pathways than any other clinical test.

Adolescent↗
PubMed1978

Assessing segmental excitability after acute rostral lesions. I. The F response.

F responses were elicited from both hands of patients shortly after they sustained unilateral cerebrovascular lesions. In 17 of 29 patients, significant abnormalities were found; F responses occurred with decreased persistence and/or amplitude on the clinically involved side, a change which was seen only in patients studied within 4 weeks of the ictus. The most prominent changes (in comparison with the clinically uninvolved side) occurred with extensive lesions. The abnormalities of F response correlated clinically with severity of the weakness, decrease in tone, and decrease in deep tendon reflexes. These changes in F response are consistent with a decreased "central excitatory state" at the spinal segmental level during the early phase after a supratentorial stroke.

Cerebrovascular Disorders↗
PubMed1977

Baclofen.

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Aminobutyrates↗
PubMed1977

Analysis of stereotyped voluntary movements at the elbow in patients with Parkinson's disease.

Patients with Parkinson's disease performed several different stereotyped elbow flexion tasks, and the electromyographic (EMG) patterns from biceps and triceps were compared with previously established normal standards. The EMG pattern during a smooth flexion task was almost always abnormal and was characterized by alternating activity in biceps and triceps. The EMG patterns during a fast flexion task were also usually abnormal although they were always composed of bursts of EMG activity of normal duration appearing alternately in the agonist and antagonist muscles. These bursts, associated with movements of the limb, have a superficially similar appearance to the EMG bursts seen with tremor-at-rest, but certain physiological differences are demonstrated. This study demonstrates that both slow (ramp) and fast (ballistic) movements are clearly abnormal in these patients with disease of the basal ganglia. In a task designed to investigate antagonist inhibition before agonist activity, a majority of the patients performed normally. This suggests that, contrary to previous claims, slowness of movement (akinesia/bradykinesia) is not due either to failure to relax or to rigidity of antagonist muscle.

Elbow↗
PubMed1976

Characteristics of myosin in nemaline myopathy.

Electron-microscopic, morphometric, histochemical and biochemical studies were carried out on muscle biopsies from a patient with the characteristic clinical and pathological findings of nemaline myopathy. The mean fiber diameter was decreased, and the vastus lateralis muscle biopsy consisted exclusively of slow twitch (Type I) fibers. Quantitative biochemical investigations revealed significantly low calcium uptake and ATPase activity of the fragmented sarcoplasmic reticulum and decreased myosin ATPase activity. The electrophoretogram of myosin showed an abnormality in the light chain pattern which could not be explained by a disproportion of normal fiber types.

Adult↗