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Biomedical subjects

A M Halliday

Publications and source records attributed to A M Halliday.

At least 37 records · Page 2Linked to original sources
PubMed1984

Autosomal dominant late onset cerebellar ataxia with myoclonus, peripheral neuropathy and sensorineural deafness: a clinicopathological report.

Three members of a family were affected by an autosomal dominant disorder comprising cerebellar ataxia, sensorineural deafness, myoclonus, and peripheral neuropathy. This is the second kindred with this syndrome reported to date. Necropsy of the proband showed loss of cells in the dentate nuclei, a reduced amount of cerebellar white matter, and pallor of the gracile tracts in the spinal cord.

Adult↗
PubMed1983

Visual evoked potential abnormalities in Charcot-Marie-Tooth disease and comparison with Friedreich's ataxia.

Pattern-reversal visual evoked potentials (VEPs), recorded in 15 visually asymptomatic patients fulfilling the clinical and electrophysiological criteria of Charcot-Marie-Tooth disease (CMTD), were abnormal in 5 and possibly abnormal in another 3. Five patients showed a prolongation of P100 latency, one a reduction of amplitude and one a possibly abnormal "scotomatous" waveform. In 9 cases abnormalities were detected on neuro-ophthalmological examination. These were poorly correlated with VEP abnormalities, except for patients with 2 or more clinical eye signs. Relative central scotomata were found in the patient with an abnormal waveform. VEP abnormalities, where present, were usually fairly comparable in the 2 eyes. In comparison with a group of Friedrich's ataxia cases there was a lower overall incidence of VEP abnormalities in CMTD, but little to suggest a qualitative difference in the nature of the visual pathway pathology. All 4 patients with unequivocally abnormal VEPs had experienced atypical symptoms suggestive of CNS involvement. In none of these was it possible to sustain an alternative diagnosis. It is concluded that a minor degree of visual pathway involvement may be present in many CMTD cases, in spite of the fact that optic atrophy is only rarely reported, and that the VEP latency may reflect the degree to which other parts of the CNS are involved.

Adolescent↗
PubMed1983

Peripheral and central sensory nerve conduction in Charcot-Marie-Tooth disease and comparison with Friedreich's ataxia.

Somatosensory evoked potentials were recorded in response to stimulation of the median nerve at the wrist and the elbow in 14 cases of Charcot-Marie-Tooth disease (CMTD). Cervical and cortical latencies were used to derive conduction times and velocities over peripheral and central segments of the pathway. Sensory conduction velocities between the wrist and the elbow were distributed bimodally (12-27 m/s and 36-70 m/s), but did not correspond with the bimodality of motor conduction velocity values in 4 cases. Three patients had severely slowed sensory conduction in one arm but only moderate slowing in the other. In the majority of cases sensory conduction was considerably faster from the elbow to the spinal cord than from the wrist to the elbow. This was most apparent in 2 young patients, suggesting that demyelination secondary to axonal degeneration may gradually progress from distal to proximal segments. Compared with a group of Friedreich's ataxia (FA) patients, almost all CMTD cases could be distinguished by a greater degree of peripheral conduction slowing (not significant in FA). In FA there was a much higher incidence of impaired conduction over central segments of the somatosensory pathway, although evidence of this was also seen in 5 CMTD cases. Three of the latter had presented with atypical symptoms suggestive of CNS involvement, and also had delayed visual evoked potentials.

Adolescent↗
PubMed1982

Double-blind controlled trial of immunosuppression in the treatment of multiple sclerosis: final report.

In a double-blind controlled trial 43 patients with relapsing-remitting multiple sclerosis were treated either with anti-lymphocyte globulin, prednisolone, and azathioprine, or with placebo preparations. Treatment began with a combination of the three medicaments but after 1 month was continued for another 14 months with azathioprine (3 mg/kg dialy) only. There was a marginally beneficial effect of immunosuppression on the overall relapse rate and clinical progression. However, there were significant effects on in-vitro lymphocyte function and in the visual evoked potentials in favour of the group receiving suppressive treatment. Placebo-treated patients of the HLA A3 tissue type had significantly more relapses than placebo-treated patients who were not of type HLA A3. Nevertheless, HLA-A3-positive patients treated with immunosuppression had significantly fewer relapses than A3-positive placebo-treated patients.

Adolescent↗
PubMed1982

Bromocriptine in management of large pituitary tumours.

Bromocriptine has an accepted place in the management of small pituitary tumours that secrete either prolactin or growth hormone. The treatment of large tumours with extrasellar extensions is more difficult, however: though surgery is the standard treatment, it is often unsuccessful in returning excessive hormone secretion to normal and may cause hypopituitarism. A prospective trial was undertaken to assess the frequency with which changes in pituitary function and size of large tumours occurs. Nineteen patients were studied before and during treatment with bromocriptine (7.5 to 60 ml/day) for three to 22 months, using contrast radiology and a detailed assessment of pituitary function. Eighteen patients had hyperprolactinaemia and two of these also had raised concentrations of growth hormones; one patient had an apparently non-functioning tumour. In 12 patients (63%) tumour size decreased with bromocriptine and no tumour enlarged. Nine patients had visual-field defects, which improved in seven, becoming normal in five. Pituitary function improved in nine patients (47%) becoming entirely normal in three. Bromocriptine should be the treatment of choice in patients with large pituitary tumours with extrasellar extensions, provided close supervision is maintained.

Adult↗
PubMed1980

Two distinct patterns of visual evoked response asymmetry in human albinism.

Results are presented which confirm that in human albinos each cerebral hemisphere receives a predominantly monocular input from the contralateral eye, giving rise to an asymmetry of the visual evoked potential (VEP) to whole-field stimulation which is similar to that for stimulation of the temporal half-field in the same individual. The further finding of two distinct, and in some respects opposite, types of topographical asymmetry raises the possibility that there are two anatomically distinct variants in the retinocortical projection in human albinism, as there are in the Siamese cat.

Albinism↗
PubMed1980

Cortical potentials following voluntary and passive finger movements.

In order to clarify the time relationship and functional significance of post-motion components of the movement-related cortical potential, averaged cortical potentials associated with voluntary and passive movements were compared mainly with respect to their scalp topography. Fourteen channels of scalp EEG, together with EOG and EMG, were simultaneously recorded in 7 healthy adult subjects while the subject was either repeating a self-paced brisk extension of a middle finger or while the experimenter was extending the middle finger by pulling up a string attached to the finger. Potentials associated with the movement were averaged opisthochronically in relation to a trigger actuated by the finger interrupting a beam of light. Seven peaks were identified in the passive movement-evoked potential. A sharp negative peak occurred over the contralateral precentral region 16 msec after the photometer trigger (N15). Another negative component (N70) formed a composite of double-peaked negativity with N15 and was seen over the frontal region with a contralateral predominance. A positive peak (P65) was recorded over the contralateral parietal region with a similar latency to N70. This N70/P65 complex has some marked similarities in terms of wave form and spatial relationship with the N + 50/P + 90 complex recorded with voluntary movement of the same finger. It is postulated that these components may be the projected potential fields from a dipole source within the central sulcus and may represent a kinesthetic feedback from the muscle afferents.

Adult↗
PubMed1980

Components of the movement-related cortical potential and their scalp topography.

In order to clarify the significance of the various components of the movement-related cortical potentials, scalp-recorded potential changes associated with voluntary, self-paced middle finger flexion and extension were studied by an opisthochronic averaging program in 14 normal right-handed subjects. Topographical study, based on 14 simultaneously recorded and averaged EEG channels, enabled us to identify at least 8 components; 4 pre-motion and 4 post-motion. The pre-motion components are the Beretischaftspotential (BP) (a symmetric early negative shift), NS'(-500 to -90) (a negative slope maximal over the contralateral precentral region and culminating in N-90 ipsilaterally), P-50 (corresponding to the pre-motion positivity, PMP), and N-10 (probably corresponding to the motor potential, MP). The post-motion components include N+50 (a sharp negative post-motion activity over the contralateral frontal region), P+90, N+160 (presumably representing sensory functions) and P+300 (a large positivity maximal over the contralateral precentral region but widely distributed).

Adolescent↗
PubMed1980

Evoked potentials following unilateral ECT. I. The somatosensory evoked potential.

The somatosensory evoked potential (SEP) was recorded in 14 patients undergoing unilateral ECT for the treatment of depression. All patients received right-sided ECT. One patient was studied on a second occasion during leftsided ECT. The index and middle fingers of each hand were electrically stimulated 1/sec throughout anaesthesia, the fit and the 0.5 h period following the fit. During barbiturate anaesthesia the SEP showed the characteristic change of the P49 component and enhancement of P32, while during the seizure induced by right ECT, the SEP was seen more clearly on the left side of the head, despite the high voltage epileptic activity. No significant asymmetries of any of the SEP components were seen post-ictally, the response returning rapidly on both sides. The subjective threshold to electrical stimulation of the fingers of each hand was significantly raised following ECT.

Adult↗