Reduced inhibition in brainstem circuits in classical trigeminal neuralgia.

OBJECTIVE: We hypothesized that prepulse modulation (PPM) would be altered in trigeminal neuralgia (TN) if suprasegmental inhibitory network involvement was present and tested our hypothesis in a group of patients with classical TN. METHODS: The study enrolled nine consecutive patients with classical TN and 14 healthy subjects. Diagnosis and classification followed the International Classification of Headache Disorders-third edition (beta version). The blink reflex (BR) and BR-PPM were recorded. Ipsilateral recordings were made after stimulating each trigeminal nerve in the patient group whereas right-sided recordings were performed after stimulating the right trigeminal nerve in the healthy subjects. A conditioning electrical stimulus was applied to the ipsilateral median nerve at interstimulus intervals (ISIs) of 50 and 100 ms before the test stimulus to the supraorbital nerve. RESULTS: The unconditioned BR recordings were similar in all groups. In the healthy subjects, the prepulse stimulus resulted in a reduced R2 magnitude (p = 0.000, Friedman's test) and longer R2 latency (p = 0.008, Friedman's test) at ISIs of 50 and 100 ms in comparison with unconditioned recordings. The R2 latency differed significantly between the unconditioned recordings and the ISI of 100 ms. In the patients with TN, no significant change was observed on either the symptomatic or asymptomatic sides. CONCLUSIONS: There is a bilateral prepulse inhibition deficit in TN, even on the asymptomatic side. Our findings provide electrophysiological evidence for suprasegmental changes and loss of filtering activity at the brainstem in level TN.

Specific brainstem and cortico-spinal reflex abnormalities in coexisting essential tremor and Parkinson's disease (ET-PD).

OBJECTIVE: We aimed to analyze functional changes at brainstem and spinal levels in essential tremor (ET), Parkinson's disease (PD) and coexisting essential tremor and Parkinson's disease (ET-PD). PATIENTS AND METHOD: Age- and gender-matched patients with tremor (15 ET, 7 ET with resting tremor, 25 ET-PD and 10 PD) and 12 healthy subjects were enrolled in the study. Diagnosis was established according to standardized clinical criteria. Electrophysiological studies included blink reflex (BR), auditory startle reaction (ASR) and long latency reflex (LLR). RESULTS: Blink reflex was normal and similar in all groups. Probability of ASR was significantly lower in ET-PD group whereas it was similar to healthy subjects in ET and PD (P<0.001). LLR was recorded during voluntary activity in all three groups. LLR II was more common in ET, PD and ET-PD groups. LLR III was far more common in the PD group (n=3, 13.6% in ET; n=4, 16.0% in ET-PD and n=7, 46.7% in PD; p=0.037). CONCLUSIONS: Despite the integrity of BR pathways, ASR and LLR show distinctive abnormalities in ET-PD. In our opinion, our electrophysiological findings support the hypothesis that ET-PD is a distinct entity.

Blink reflex in patients with postparalytic facial syndrome and blepharospasm: trigeminal and auditory stimulation.

OBJECTIVE: The enhancement of blink reflex (BR) excitability was shown in patients with postparalytic facial syndrome (PFS) and essential blepharospasm (EB). We prospectively investigated patients with PFS and EB whether BR alterations demonstrated by trigeminal stimulation will similarly be observed upon auditory stimulation. METHODS: Fifteen patients with PFS, 15 patients with EB, and 30 healthy volunteers were involved. Electrically stimulated trigeminal BR and auditory BR were studied bilaterally. RESULTS: The mean R2 amplitude and duration values were highest in EB patients, being significantly higher than PFS patients (p < 0.05) and control group (p < 0.01). The mean R2 duration in PFS patients were also significantly longer in compared to control group (p = 0.025). EB patients showed a higher mean R (auditory) amplitude and duration than PFS patients (p < 0.05) and controls (p < 0.04). The mean R (auditory) duration was longer on symptomatic side of PFS patients in compared to controls (p = 0.05). CONCLUSIONS: We observed that there is an enhanced excitability of BR circuit in postparalytic facial syndrome and essential blepharospasm, which could be evoked by auditory stimulation in addition to trigeminal stimulation. SIGNIFICANCE: The enhanced excitability in patients with EB and PFS probably originates from the final common pathway of BR circuit, namely facial motor or premotor neurons.

Neuropathy patterns differ in patients with diabetic complications.

PURPOSE: Diabetic polyneuropathy (PNP) is an important risk factor for foot ulcers. Diabetic dermopathy is more frequent in patients with diabetic neuropathy. We compared clinical and electrophysiological characteristics of PNP localizations/recurrences of foot ulcers, and diabetic dermopathy (DD) between sexes. METHODS: Eighty-eight diabetic patients (44 men, 44 women) had an evaluation regarding detailed history of their diseases, lesion-related data, and clinical examination. Nerve conduction velocities (NCV), compound motor action potentials (CMAP), distal latencies (DL), and sensory nerve action potentials were assessed from the right and left peroneal, right median/ulnar nerves. RESULTS: The presence of DD was more common in men (p < 0.001). The mean NCV of ulnar nerves was slower (p < 0.001); mean CMAP values were lower (p = 0.006); and mean DL was longer in men with compared to women (p = 0.003). Although EMG features of peroneal nerves showed no significant difference, diabetic men had more common and severe peroneal nerve involvement (p = 0.004). Carpal tunnel syndrome was more common in women, though not significant. Patients with right-sided ulcers had lower CMAP amplitudes on the right peroneal nerves in regard to left peroneal nerves (p = 0.009). CONCLUSIONS: Our findings suggest that ulnar nerves are more commonly involved in men, with lower CMAP slower NCV values, and longer DL values.

Clinical and nerve conduction studies in female patients with diabetic dermopathy.

This study aims to assess the clinical and electrophysiological characteristics of diabetic polyneuropathy (PNP) in female patients. We investigated clinical and electrophysiological features in 175 female patients with diabetes mellitus to compare those with PNP only, diabetic dermopathy (DD), or diabetic foot (DF). Among clinical features, the loss of deep tendon reflexes, the presence of negative sensory symptoms, superficial sensory loss, and the loss of vibration sense were more common in DD patients than PNP patients. As compared with DD patients, the presence of skin atrophy, superficial and positive sensory symptoms were more common in DF patients. Neuropathic symptom and disability scores were significantly higher in DD and DF patients than PNP patients. In the electrophysiological studies, the only significant difference was observed in the mean distal latencies for ulnar nerves, which were longer in DD patients as compared with PNP patients, but similar between DD and DF patients. All other parameters failed to show significant difference among patients, though values for DD patients lied in between PNP and DF patients. Carpal tunnel syndrome was present in 45% of PNP patients, 63.8% of DD patients, and 50% of DF patients (P = 0.031). Our results suggest that female patients with diabetic dermopathy might have a more severe sensorial neuropathy than patients without these skin lesions.

The cutaneous silent period in carpal tunnel syndrome.

OBJECTIVES: The cutaneous silent period (CSP), a sustained voluntary contraction following a painful stimulus applied over the appropriate dermatome produces a brief period of electrical silence, may be useful if the routine nerve conduction studies and needle electromyography are insufficient to diagnose entrapment neuropathies. MATERIAL AND METHODS: To investigate whether symptomatic or asymptomatic patients with entrapment neuropathies are differed in terms of CSP, one hundred fifty four hands of 58 patient and 19 controls were studied according to the clinical and electrophysiological findings. RESULTS: CSP latency and duration could be affected in severe forms of entrapment neuropathies. However, even in patients with dysesthetic pain -which lead to the belief that small fibers may be involved-, results of electrophysiological evaluation could not support the clinical findings. CONCLUSION: In this study it was suggested that CSP studies provide no additional information in entrapment neuropathies.

Is diabetic dermopathy a sign for severe neuropathy in patients with diabetes mellitus? Nerve conduction studies and symptom analysis.

OBJECTIVE: To assess if diabetic dermopathy (DD) is a sign for severe polyneuropathy (PNP). METHODS: We investigated the clinical and electrophysiological characteristics of 166 diabetic men (59.5+11.1 years) with different degrees of peripheral nerve involvement. RESULTS: All of the clinical variables were more common in patients with diabetic foot ulcers (DF) than in patients with sole PNP (P<0.001). Only the loss of superficial and vibration sense was more common in the DF patients than the DD patients (P<0.02). Nerve conduction studies showed the mean compound muscle action potentials (CMAP) were smaller in the DD and DF patients than the PNP patients for peroneal, median and ulnar nerves (P<0.01). The mean nerve conduction velocities (NCV) of all nerves were slower in the DD and DF patients in compared to sole PNP patients (P<0.01). The mean distal latencies (DL) of the DD/DF patients were longer than the PNP group. CONCLUSIONS: The DD and DF patients did not significantly differ in CMAP, NCV, and DL. SIGNIFICANCE: Both clinical and electrophysiological features of DD and DF are similar, and significant different than PNP alone. These results suggest that DD is an important clinical sign for more severe neuropathic impairment.

The influence of age in peripheral facial palsy on brainstem reflex excitability.

BACKGROUND: Neuronal plasticity is expected to be different at different ages and adaptive changes developing after peripheral facial palsy (PFP) may provide a clue in this respect. AIMS: To investigate the difference in the reorganization developing after facial nerve damage between patients who developed PFP at childhood-youth and middle-old age. PATIENTS AND METHODS: Twenty-two patients were divided into two groups according to the age-at-onset of PFP; young (PFP 1), and elderly (PFP 2). Two age-matched control groups (C 1 and C 2) comprised of 32 healthy subjects were included in the study. The latency, R(2) area, and recovery of the R(2) area of the blink reflex were investigated. STATISTICAL ANALYSIS: ANOVA and Bonferroni tests were used. RESULTS: The R(2) areas were significantly greater on the intact side of the PFP 1 group as compared to that in the control group ( P =0.012). The recovery of R2 component was significantly enhanced on the symptomatic (P = 0.027), and intact (P = 0.041) sides in PFP 1 as compared to that in the C 2 group at the stimulus interval of 600 ms. Significant enhanced recovery was noted at 200 ms stimulus interval on the symptomatic side of the two PFP groups (PFP 1, P = 0.05 and PFP 2, P = 0.025) and on the intact side of the PFP 1 group (P =0.035) as compared to that in the control groups. CONCLUSION: Young age-at-onset of PFP is associated with more prominent excitability changes developing at the neuronal and interneuronal level.