Measuring vibration sensations with graduated tuning fork. Simple and reliable means to detect diabetic patients at risk of neuropathic foot ulceration.

ABSTRACT

To find a simple and reliable means to measure vibration sensations, 189 diabetic patients and 88 control subjects were tested at different sites with a graduated tuning fork. Within-test variation at big toes reached 8.4% in diabetic patients vs. 2.2% in control subjects. Mean contralateral variation was 7.5% in diabetic patients vs. 2.5% in control subjects. Tuning-fork sensations were inversely correlated with duration of diabetes, whereas no correlation was found with HBA1c levels or the severity of retinopathy. Ninety-nine (52%) patients had vibratory sensation at big toes of less than 99th percentile of normal values for age. In addition, 51% of the patients with clinical symptoms at extremities (n = 67), 70% of the patients without tendon reflexes (n = 50), and 75% of the patients with abnormal nerve conduction velocities (n = 60) also had low vibration sensations. All patients with lower-limb injuries (n = 7) had values at big toes of less than 2. Altogether, the graduated tuning fork represents a simple and reliable alternative to quantitate vibration sensations. Long-term follow-up of asymptomatic patients will indicate whether these abnormalities reflect underlying neuropathy. Patients with abnormal values at screening will necessitate additional investigations and special foot-care education programs.