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Biomedical subjects

J W Howe

Publications and source records attributed to J W Howe.

At least 37 records · Page 2Linked to original sources
PubMed1985

Inter- and intra-examiner reliability of the upper cervical X-ray marking system.

This paper investigates the reliability of the upper cervical X-ray marking procedure. The measurement chosen to be examined was atlas laterality. Twenty X-rays were marked by three experienced upper cervical practitioners for the inter-examiner reliability testing, and two of the doctors marked 10 of the films twice for intra-examiner testing. The average measurement for the 60 markings was 1.83 degrees. The average difference between the 3 doctors was 1.05 degrees. The range of error is 57 percent of the average measurement. With interval agreements, it is shown that at the point where all 3 doctors agree 80 percent of the time, the range of error is 2 degrees, this being over 100 percent of the average measurement. The range of error percentages for the 2 intra-examiner tests were 41 percent and 71 percent. It is concluded that with ranges of error of this magnitude any measured differences produced using this system will be just as likely to be from marking error as from actual atlas position change. This should be considered by practitioners who consider these measurements to be objective evidence for demonstrating the results of chiropractic adjustments.

Cervical Atlas↗
PubMed1984

The objective assessment of contrast sensitivity function by electrophysiological means.

In recent years it has been shown that it is of considerable clinical value to determine the visual contrast sensitivity function of the patient. This can reveal the wider effects of pathology on the visual system where visual acuity may or may not be affected. There is a comprehensive literature on subjective approaches of obtaining this function in the clinical environment but very little on alternative objective methods. This paper describes the latter approach, which exploits electrophysiological techniques using the visual evoked cortical potential (VECP) to checkerboard onset-offset stimulation. Its application in a variety of disorders of the visual system is described. The importance of selecting the most appropriate stimulus parameters is discussed, and the relative advantages and disadvantages as compared with psychophysical methods are appraised.

Adult↗
PubMed1981

Visual involvement in Friedreich's ataxia and hereditary spastic ataxia. A clinical and visual evoked response study.

Visual involvement was assessed in 21 patients with Friedreich's ataxia and in 17 patients with spastic ataxia by neuro-ophthalmic examination and by recording visual evoked responses (VERs). Two thirds of the patients with Friedreich's ataxia had some degree of visual impairment and an abnormal VER, whereas only three of the 17 patients with spastic ataxia showed abnormalities. The patients with Friedreich's ataxia could be subdivided into two groups, one with and the other without visual involvement; there was no correlation between the presence and severity of visual involvement and age or duration of symptoms in the group as a whole. Patients with the most severe degrees of visual impairment usually had flat VERs, whereas in less severely affected cases, the responses were reduced in amplitude, were delayed, and showed an increased degree of temporal dispersion. The findings have pathophysiological implications and raise the question of heterogeneity in Friedreich's ataxia.

Adolescent↗
PubMed1981

Pattern visual evoked responses in hereditary spastic paraplegia.

Pattern visual evoked responses were studied in 13 patients from nine families with dominant herditary spastic paraplegia and in seven sporadic cases. The responses were normal in all the dominantly inherited cases but abnormal in three of the seven sporadic cases.

Adolescent↗
PubMed1980

Leber's optic neuropathy: clinical and visual evoked response studies in asymptomatic and symptomatic members of a 4-generation family.

A clinical and neuro-ophthalmological examination using tests of visual acuity, quantitative visual field analysis, tests of colour discrimination, ophthalmoscopy, and pattern visual evoked responses was performed on 2 symptomatic and 16 asymptomatic members of a family with Leber's optic neuropathy. The visual evoked responses were abnormal in the 2 clinically affected males and in 1 asymptomatic male. Tests of colour discrimination with Ishihara plates, the Farnsworth-Munsell 100 hue test, and the Nagel anomaloscope revealed abnormalities in 8 asymptomatic family members, with the Farnsworth-Munsell test proving to be the most sensitive to mild abnormalities of colour discrimination. The occurrence of detectable neuro-ophthalmological abnormalities within this family is in keeping with the expected pattern of transmission of Leber's optic neuropathy. The significance of detection of presymptomatically affected cases and asymptomatic carriers is discussed.

Adolescent↗
PubMed1979

Herpes simplex virus uveitis and optic neuropathy. An experimental investigation.

The sequence of events which follows the intravitreal injection of herpes simplex virus (HSV) into one eye has been observed as it affects the eyes, optic nerves, and optic chiasm. Initially the injected (right) eye showed an intense iridocyclitis and about 16 days after inoculation an exudative retinal detachment was observed. A similar sequence of events occurred in the uninjected (left) eye about 6 days later. HSV has been shown to pass along the right optic nerve towards the chiasm and from there down the left optic nerve. The primary route of spread appears to be via neuroglial cells rather than the axons. Tissue necrosis and re-myelination have been observed.

Animals↗
PubMed1979

Prognostic value of the visual evoked response.

29 patients with visual defects have been followed up by serial recording of the visual evoked response (VER). Those patients in whom the VER was initially normal all made a satisfactory visual recovery. In others an initial attenuated response was followed by an improvement in vision and this was accompanied by normalization of the VER. A third group of patients with an initially subnormal VER have remained blind and the VER has shown no improvement.

Aged↗
PubMed1974

The displaced lens.

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Abnormalities, Multiple↗