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Biomedical subjects

E M Sedgwick

Publications and source records attributed to E M Sedgwick.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1987

Recovery profile of single motoneurons after electrical stimuli in man.

The H-reflex of 120 soleus motoneurons was recorded using fibre EMG. The recovery profile of these motoneurons was studied during monitoring surface H-reflex records in 28 adult subjects. The spectrum of motoneurons tested was homogeneous with two extremes of neurons having different characteristics. A motoneuron population (forming about 69% of our sample) had a high threshold level for electrical stimuli, short recovery time, and short recovery fringe time (called type A). A second population of motoneurons (forming about 20-30% of our sample) had a low threshold level for electrical stimuli, long recovery fringe time (called type B). During an isometric muscle contraction every motoneuron showed an early shift in recovery time (i.e. each had a shorter recovery time) with shortened recovery fringe time. These changes were larger for motoneurons type B than motoneurons type A. With paired identical electrical stimuli of varying interstimulus intervals a motoneuron may fire in response to the conditioning and test stimuli giving an H2, but not in response to both stimuli. This occurred for interstimulus intervals of 4-11 ms. A strong inhibition period was recorded with interstimulus intervals of 12-80 ms in which all motoneurons did not show any recovery. Most motoneurons recovered in orderly fashion between 80 and 300 ms of interstimulus interval, and this recovery coincided with the fast recovery recorded in surface H-reflex. All motoneurons were recovered by 3000 ms of interstimulus intervals. These findings emphasize the importance of eliciting the H-reflex every 3-5 s in H-reflex methodology in order to be assured that all excited motoneurons have been recovered.

Adult↗
PubMed1987

Brainstem auditory evoked potential abnormalities in myelomeningocoele in the older child.

Brainstem auditory evoked potentials and clinical findings were examined in 18 children over the age of 5 years who were born with myelomeningocoele which was closed at birth, and whose hydrocephalus was managed by long term shunting in most of them. The potentials were compared with age and sex matched normal subjects and with four patients with hydrocephalus only. All but one had an abnormal brainstem auditory evoked potential with 72% showing a delay in the II-V and I-V interpeak latencies of more than three standard deviations. It is proposed that the abnormalities are a reflection of brainstem dysgenesis which is part of an associated Arnold-Chiari malformation, though the malformation was clinically asymptomatic in all. The usefulness of the brainstem auditory evoked potential for assessing the course of hydrocephalus and for predicting symptomatic Arnold-Chiari malformation is questioned.

Adolescent↗
PubMed1987

Normality of single fibre electromyographic jitter: a new approach.

The distribution of jitter values derived from single fibre electromyography (SFEMG) in normal extensor digitorum communis has been found to be skewed. A reciprocal transformation technique is presented which renders the distribution normal. The distribution enables SFEMG changes to be assessed using parametric statistics. The relationship of the new technique to existing methods of analysis of SFEMG is discussed.

Electromyography↗
PubMed1987

Evaluation of the dermatomal somatosensory evoked potential in the diagnosis of lumbo-sacral root compression.

The dermatomal somatosensory evoked potential from the lumbo-sacral dermatomes was recorded from 21 patients with radiographically and surgically (20) proven lumbo-sacral root compression due to prolapsed intervertebral disc or canal stenosis. The potential was abnormal in 19 of the 20 surgically proven cases. The dermatomal somatosensory evoked potential is as accurate as myelography for diagnosis but has the advantage of being non-invasive and repeatable. It provides useful additional diagnostic and pathophysiological information about lumbo-sacral root compression.

Adult↗
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↗
PubMed1983

Mianserin, maprotiline and the electroencephalogram.

1 EEGs were recorded from patients with depressive illness before and after four weeks of treatment with mianserin, maprotiline or placebo. 2 Visual analysis of the records showed a small but statistically significant increase in frequency of beta activity in the mianserin group. 3 One subject taking maprotiline developed spike and wave discharges but had no convulsive seizures. 4 The findings do not support those of previous studies. It seems that changes seen in the EEG early after treatment are not sustained for four weeks.

Adult↗
PubMed1983

Spinal inhibition in man: depression of the soleus H reflex by stimulation of the nerve to the antagonist muscle.

A period of inhibition of the soleus H reflex, called D1 inhibition, follows stimulation of the nerve to the antagonist muscles, the peroneal nerve, in normal man. The results confirm earlier descriptions of D1 and show an intracord latency of approximately 4-5 msec and a reduction of the H reflex by about 60%. D1 reaches its maximum 15-20 msec after stimulation and its duration is more than 30 msec. Effective stimuli were volleys of two to five pulses given as 10 msec duration bursts at a strength of 1.2 motor thresholds. Cutaneous afferents were ineffective and the possibility that D1 is mediated by low threshold muscle afferents is discussed. D1 produces the same proportions of inhibition of the H reflex when the H reflex is facilitated by plantarflexion or depressed by dorsiflexion.

Adult↗
PubMed1983

Spinal cord stimulation in the United Kingdom.

All the medical, surgical and engineering personnel in the UK who have used spinal cord stimulation (SCS) in patients, attended a workshop to discuss their results. The major use of SCS has been for multiple sclerosis and intractable pain. It was concluded that the technique benefited up to two thirds of patients with bladder dysfunction, and that pain and possibly spasticity also responded to SCS, but other manifestations of multiple sclerosis did not. Further information on long term benefit is needed and the use of SCS in other conditions, such as spinal injury and peripheral vascular disease, is not yet established. SCS cannot be recommended for use outside large centres as x-ray screening, urodynamic and neurophysiological assessment facilities are required as well as biological engineering assistance.

Electric Stimulation Therapy↗