Objective: To assess the facial and trigeminal nerve involvement in diabetic patients using blink reflex study and direct facial motor conduction study.

Method: The subjects were 397 diabetic patients and 34 normal controls. Diabetic patients were subdivided into two groups based on the findings of nerve conduction studies of limb nerves.: Group I, patients with diabetic polyneuropathy; Group II, patients without diabetic polyneuropathy. The blink reflexes and direct facial motor responses and R1 latency/direct response latency (R/D) ratio were obtained in all the subjects. R1 latency was correlated to the findings of nerve conduction studies of limb nerves.

Results: 1) R1 latencies or R2 latencies were abnormally prolonged in 22.4% of Group I, 3.3% of Group II, and direct facial responses were abnormal in 11.8% of Group I, 2% of Group II. 2) There were no significant differences in R/D ratio between the two groups. 3) These findings suggest that not only the facial nerve, but also the trigeminal nerve or brain stem could be affected in diabetic patients with polyneuropathy.

Conclusion: In diabetic patients, blink reflex can provide useful information in determining the degree and distribution of cranial nerve and brain stem lesions.

Objective: To compare the R3 response of the blink reflex in medullar and spinal cord lesion and to investigate whether the reflex arc of the R3 response descend to the cervical spinal cord or not.

Method: We have studied 3 patients with medullar lesion and 5 patients with cervical spinal cord or vertebral lesion. Normal ranges of the R3 response refer to the results suggested by Moon et al.

Results: In 3 patients with medullar lesion, two patients with lateral medullar lesion showed delayed R3 latency or no evoked potential. Four patients with cervial spinal cord lesion showed no R3 response. In one patient with disc protrusion R3 was normal.

Conclusion: Our results support the hypothesis that the reflex arc of the R3 response descend to the cervical spinal cord.

Objective: This study was designed to observe how the mento-blink reflex (MBR) study is valuable in evaluating the inferior alveolar nerve injury.

Method: Eleven patients, suffering from the sensory discomfort after extraction of the third molar, and a control group consisting of 20 healthy individuals participated in the clinical neurosensory test (CNST) and the MBR study. The score of CNST was from 0 (normal) to 5 (worst) according to sensory deficit, and the results of MBR were divided into 3 groups: normal; prolongation of R₂ latency; no response.

Results: In the control group, R₂ latencies of right and left were 31.9⁑6.1 msec and 31.5⁑5.9 msec, respectively with the difference of 1.3⁑0.9 msec. The abnormality in the MBR study in patients was correlated with the subjective sensory symptoms (p=0.017) and the abnormality of MBR response was proportional to the score of the CNST.

Conclusion: We concluded that the MBR study is a useful diagnostic tool in reflecting the inferior alveolar nerve lesion.

Objective: To determine the normal data of R3 component of blink reflex in normal adults.

Method: Subjects included 17 healthy males and 16 healthy females. Five trials of blink reflex were recorded from each side. The shortest latency of R3 response was the shortest among the 5 consecutive trials was selected.

Results: Mean onset latency of R3 was 79.8 ms, mean duration 31.0 ms, mean amplitude 399.5 ㄍV and a side-to-side difference of latency was 2.3 ms. The amplitude of R3 decreased with age. The latencies and durations of R1 and R2 were not related to those of R3. The amplitude of R2 was correlated with that of R3.

Conclusion: This data will be useful for the localization of brainstem and cervical spinal cord lesions.

The study of blink reflexes was carried out to demonstrate the correlations, if there were, between the stage of diffuse axonal injury(DAI) and the abnormality of blink reflexes. The blink reflex was recorded in 20 healthy adult subjects and 22 patients with DAI who were classified according to Adams' classification(DAI I; 7, DAI II; 9 and DAI III; 6). The latencies and amplitudes of R1 and R2 in patients with DAI were compared with those of healthy subjects.

The results were as follows; 1) In 20 subjects of patient group, the latencies of R1 were all within a normal range. In 2 subjects, the difference in latencies between the two sides was above 1.4 msec. 2) In 15 subjects, R2 was absent or delayed, and reduced in the size of amplitude in all. Nine were affected bilaterally, and 4 were unilaterally. 3) Seventy one percent of patients in each stage represented abnormal findings. 4) There were no correlations between the DAI stage and the blink reflex.

This study demonstrated that the polysynaptic R2 was more profoundly suppressed than the oligosynaptic R1 in a diffuse axonal injury because of a loss or decrease of suprapontine facillitation, which influenced the trigeminal spinal complex and the interneuron of lateral reticular formation.

Leprosy is an infectious disease caused by Mycobacterium leprae and characterized by dermal and peripheral nerve lesions. The facial nerve is also frequently involved in leprosy. There are a few electrophysiologic studies on the facial nerve involvement in leprosy patients, but there is no electrophysiologic study on the facial nerve involvement in cured leprosy patitents. So we performed facial nerve conduction study and Blink reflex study in 19 cured leprosy patients who have been managed with Dapsone for a long time. Facial motor latencies were prolonged in 11 patients(57.9%).: 10 of 15 patients in lepromatous type; 1 of 4 patients in tuberculoid type. Prolonged latencies were shown in temporal branch, zygomatic branch, buccal branch, and mandibular branch in 9(47.4%), 6(31.6%), 5(26.3%), and 3(15.8%), respectively. Blink reflex study suggests combined facial nerve and trigeminal nerve lesion in 2 patients.