Augmented asymmetrical visual field dependence in asymptomatic diabetics: evidence of subclinical asymmetrical bilateral vestibular dysfunction.

BACKGROUND: Diabetes negatively affects the vestibular system in many ways, with vestibular dysfunction (VD), a co-morbidity with a high prevalence in diabetics. PROCEDURES: The ability to perceive subjective visual vertical (SVV), as a sign of vestibular dysfunction, and visual field dependence was measured using a computerized rod and frame test (CRAF). Alignment errors recorded from 47 asymptomatic Type II diabetics (no vertigo or falls, without peripheral neuropathy or retinopathy) were compared to 29 healthy age matched (46-69years) controls. FINDINGS: Visual field dependence was significantly larger and more asymmetrical in the diabetics than controls. In the absence of any visual references, or when a vertical reference frame was provided, SVV perception was accurate in both groups, with no significant difference between the controls and diabetics. During tilted frame presentations, the proportion of subjects with either SVV deviations, or an asymmetry index, larger than an upper limit derived from the control data was significantly greater in diabetics than controls. CONCLUSION: These results suggest that the decreased ability to resolve visuo-vestibular conflict in asymptomatic diabetic patients (free of retinopathy and peripheral neuropathy) compared to controls may be related to diabetic complications affecting vestibular structures and thus causing a decompensation of subclinical vestibular asymmetries.

Cutaneous two-point discrimination thresholds and palpatory sensibility in chiropractic students and field chiropractors.

OBJECTIVE: To investigate differences in cutaneous 2-point discrimination and palpatory sensibility at different stages in a chiropractic training course and in field chiropractic practitioners. METHODS: Static 2-point discrimination and palpation thresholds of the skin in the dominant index finger were measured in 102 subjects taken from the first and final years of a chiropractic degree/masters course and practicing field chiropractors. Two-point discrimination measurements were obtained by applying modified electronic engineering calipers mounted on a lever arm, which allowed the points to be lowered onto the skin at a constant rate and pressure. Palpation measurements were made by locating a nylon monofilament under a variable number of sheets of paper held in a purpose-designed frame. Paper thickness was measured by using electronic engineering calipers. Differences in the 2-point discrimination and palpation threshold measurements recorded between cohorts were analyzed by using 1-way analysis of variance (ANOVA) and Tukey-Kramer multiple comparison tests. RESULTS: A statistically significant reduction was observed in 2-point discrimination thresholds between first-year (control group) and fifth-year chiropractic students (P <.001) but not between the control group and the practicing field chiropractors. A progressive increase was observed in palpatory sensibility, as determined by the thickness of paper through which the nylon monofilament could be felt, from first-year chiropractic students to practicing field chiropractors. A significant difference in palpatory threshold was also found between first year students and chiropractors (P <.05). Although both 2-point discrimination and palpatory discrimination thresholds were different between groups, no statistically significant correlation could be made to link statically recorded 2-point discrimination acuity with palpatory sensibility. CONCLUSION: These investigations support previous research that 2-point discrimination improved through the chiropractic training program at the Anglo-European College of Chiropractic but that this appeared not to be retained into field practice. However, the changes in palpatory ability were maintained and improved on in professional practice, suggesting that 2-point discrimination thresholds do not provide a good measure of palpatory ability.

Differences between the cutaneous two-point discrimination thresholds of chiropractic students at different stages in a 5-year course.

OBJECTIVE: To investigate differences between the tactile acuity of the fingers measured at different stages in a chiropractic training course. METHODS: Two-point discrimination (2-PD) thresholds for the skin of the dominant and nondominant index fingers and the dominant forearm were measured in 74 subjects taken from the 5 years of a chiropractic degree course. Measurements were made with modified electronic engineering callipers mounted on a lever arm, which allowed the points to be lowered onto the skin with a constant pressure. ANALYSIS: Differences in the 2-PD measurements recorded among the year-groups were analyzed with 1-way analysis of variance and between the dominant and nondominant index fingers with the paired Student t test. RESULTS: Students in years 4 and 5 of the course had significantly smaller mean 2-PD threshold values (P <.05) for both dominant (year 5: 1.39 +/- 0.06 mm) and nondominant (1.50 +/- 0.08 mm) index fingers compared with students in year 1 (dominant mean, 1.66 +/- 0.09 mm; nondominant mean, 1.80 +/- 0.10 mm). There was no significant difference between the 2-PD thresholds measured on the forearm of any of the groups. When the data from all 5 years were grouped, the 2-PD thresholds for the dominant index finger (mean 1.52 +/- 0.035 mm) was found to be significantly smaller (paired Student t test, P <.0001) than for the nondominant finger (mean 1.65 +/- 0.038 mm, n = 74). CONCLUSION: The results demonstrate that the tactile acuity of students in the later years of the course at the Anglo-European College of Chiropractic is greater than that of students in the first year. This may be a result of the intensive training in palpatory techniques that the students receive during their course. However, this requires confirmation by further investigation.