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Biomedical subjects

E M Sedgwick

Publications and source records attributed to E M Sedgwick.

At least 19 recordsLinked to original sources
PubMed1992

The perceptions of force and of movement in a man without large myelinated sensory afferents below the neck.

1. Motor memory and the sense of effort have been investigated in a man with a complete large fibre sensory neuropathy for over 16 years. The perceptions of pain, heat, cold and muscular fatigue remained but he was without perceptions of light touch and proprioception below the neck. 2. The subject was able to discriminate weights held in the hand with an accuracy only slightly worse than control subjects (20 g in 200 g) when forearm movement and visual inspection were allowed. With eyes shut however he could only distinguish a weight of 200 g from 400 g. It is concluded that a crude sense of effort remains which may have a peripheral origin. 3. A limited motor memory was also present, which allowed him to maintain a posture or continue a simple repetitive movement. No novel movement was possible without visual feedback. 4. Differences in movement ability between this subject and others with similar if less pure sensory neuropathies are ascribed to rehabilitation.

Adult↗
PubMed1990

A cerebral hemisphere influence on cutaneous vasomotor reflexes in humans.

Cutaneous vasomotor reflexes (CVR), the transient waves of cutaneous vasoconstriction after stimuli, such as a cough, were recorded from the digits of patients with unilateral frontoparietal lesions using a laser doppler flowmeter. Vasoconstriction was 6-15 times greater on the fingers contralateral to the lesions, an effect which was independent of the temperature difference between limbs. CVRs may be tonically inhibited under normal circumstances by control from the cerebral hemispheres.

Adult↗
PubMed1988

Loss of evoked potentials during spinal surgery due to spinal cord hemorrhage.

The cortical somatosensory evoked potential (SEP) disappeared during corrective spinal surgery in a patient with muscular dystrophy. The patient died 18 hours after surgery. Autopsy revealed an intramedullary hemorrhage 4 mm in diameter in the posterior horn of the cervical spinal cord. Microscopically, hypoxic neurons were seen adjacent to the hemorrhagic area, implying that the lesion was at least 6 hours old. The hemorrhage corresponded to the loss of SEPs and confirms that spinal cord monitoring can detect such lesions.

Adolescent↗
PubMed1988

The effect of frontoparietal lesions on stability and tremor in the finger.

Assessment of stability and tremor in the fingers in patients with unilateral frontoparietal lesions involved the task of attempting to keep the finger still on a typewriter key connected to a strain gauge. In patients with no or minimal pyramidal motor signs and/or cortical sensory signs, the amplitudes of tremor compared with normal controls showed that the contralateral side was not significantly different from normal but that the ipsilateral side was significantly less stable than normal. In normal subjects the tremor seen during the task, and determined from the fast Fourier transform, (FFT), showed a peak at 1-3Hz and a gradual falling off to background levels by 6Hz or so. In patients with spasticity, weakness and sensory impairment there was an additional peak of tremor seen at 6-7Hz ipsilateral to the cerebral lesion.

Adult↗
PubMed1988

Stability and tremor in the fingers associated with cerebellar hemisphere and cerebellar tract lesions in man.

Stability and tremor in the fingers were assessed by a new technique in patients with unilateral cerebellar syndromes. In 11 patients with unilateral cerebellar hemisphere lesions tremor was observed with either clear tremor at 5-7 Hz or prolongation of the tremor profile out to 11 Hz. In 10 patients with unilateral cerebellar lesions associated with ipsilateral past-pointing there was an asymmetry in finger stability. Compared with normal subjects there was a significant decrease in stability contralateral to the lesion, while the ipsilateral side's stability was not different from normal. In patients with high brain stem lesions at the level of cranial nerves VII and above, tremor had frequencies of 5-7 Hz. In those with lower brain stem lesions, often with long tract signs as well, the frequencies of tremor were faster, 8-11 Hz, which may reflect damage to cerebellar inflow tracts. A broad if not specific correlation was found between clinical condition, site of lesion and finger stability and tremor.

Adolescent↗
PubMed1988

Occult spinal dysraphism in established congenital dislocation of the hip.

Of a consecutive series of 117 one-year-old infants with 130 established dislocations of the hip, 11% failed to respond to primary surgical treatment. Genetic and iatrogenic factors accounted for half the failures. There were no obvious causes in the remainder, though a few had the superficial stigmata of spinal dysraphism, and by two years of age, most of the group had developed a lateral rotation posture of the affected leg associated with a relatively smaller foot on that side. Radiologically, the femoral head had drifted and rotated laterally out of the surgically deepened acetabulum, causing persistent subluxation. Although there was no clinical evidence of sensory or motor denervation, sensory spinal evoked potential tests revealed the presence of neurological deficits in the majority of patients in this group.

Foot↗
PubMed1986

Somatosensory evoked potentials from posterior tibial nerve and lumbo-sacral dermatomes.

Techniques for recording the somatosensory evoked potential following stimulation of the skin of L5 and S1 dermatomes are described and validated. Normal data and their range are given for 54 subjects (108 legs). The latency of the peak of the first positive wave (P40) can be predicted from the subject's height from the regression formulae: P40 latency in msec = height in metres X 23.7 + 8.6 for the L5 dermatome. P40 latency in msec = height in metres X 24.5 + 8.7 for the S1 dermatome. P40 latency in msec = height in metres X 15.0 + 14.6 for the posterior tibial nerve. The standard deviations are 2.90 for L5; 2.95 for S1 and 1.60 for the posterior tibial nerve. Age and sex of the subjects had no significant effect. The data will have value when dermatomal somatosensory evoked potentials are used to investigate radiculopathies.

Adolescent↗
PubMed1979

Modulation of the tonic stretch reflex by monoamines.

The effects of L-DOPA and 5-HTP on the tonic stretch reflex (TSR) in the decerebrate rat were studied. L-DOPA facilitated the TSR in a dose-dependent manner. The facilitation of the TSR was blocked by pimozide. A sensitive electromygraphic (EMG) technique capable of recording single motor unit discharges was used. The EMG results suggest that gamma motoneuron sensitivity was increased to a greater degree than alpha motoneuron sensitivity during the facilitation by L-DOPA. The L-DOPA-induced facilitation persisted in animals partly depleted of 5-hydroxytryptamine (5-HT) by reserpine, p-chlorophenylalanine or 5,6-dihydroxytryptamine. 5-HTP inhibited the TSR in a dose-dependent manner. It is concluded that DA not 5-HT is the amine which normally mediates facilitation of the TSR after L-DOPA and that gamma motoneuron activation is more likely to be involved to a greater degree than alpha motoneuron activation in the neural mechanisms of the facilitation.

5-Hydroxytryptophan↗
PubMed1979

Delayed cervical somatosensory potentials in cervical spondylosis.

The cervical somatosensory evoked potential after median nerve stimulation was recorded in 14 patients with cervical spondylosis with radiculopathy and, in 10 cases, myelopathy. Four patients had normal potentials, five showed delayed potentials, and in five others no potential could be seen.

Adult↗
PubMed1979

Chlormethiazole--no hangover effect but not an ideal hypnotic for the young.

The hangover effects of 768 mg chlormethiazole, an hypnotic with a half-life of approximately 4 hr, were compared with those of placebo in a double-blind cross-over study in 8 young subjects. Ten hours after dosing there were no differences between the preparations in the subjects' psychomotor performance, EEG sleep scores, or visual analogue ratings. Thus, an hypnotic which is rapidly removed from the body may confer considerable advantages. However, all 8 subjects had unpleasant nasal symptoms following chlormethiazole, and it is therefore not an ideal hypnotic for this age group.

Adult↗
PubMed1978

Properties of a spinal somatosensory evoked potential recorded in man.

Somatosensory evoked potentials were recorded from the skin overlying the cervical and lumbar spinal cord of man after stimulation of median and tibial nerves respectively. The early negative component (N11) of the cervical potential and the negative lumbar potential (N14) were studied. The spatial properties of N11 and N14 indicate a spinal cord origin. Evidence partly from threshold studies, shows that the low threshold cutaneous afferent fibres were responsible for activating the generators of the potentials. A conditioning test stimulation procedure supports a postsynaptic generator. It is concluded that N11 and N14 have properties similar to the cord dorsum potentials recorded in animals and probably have the same generator, the neurones of the dorsal horn.

Afferent Pathways↗