Abdominal acupuncture reduces laser-evoked potentials in healthy subjects.

OBJECTIVE: Acupuncture is known to reduce clinical pain, although the exact mechanism is unknown. The aim of the current study was to investigate the effect of acupuncture on laser-evoked potential amplitudes and laser pain perception. METHODS: In order to evaluate whether abdominal acupuncture is able to modify pain perception, 10 healthy subjects underwent a protocol in which laser-evoked potentials (LEPs) and laser pain perception were collected before the test (baseline), during abdominal acupuncture, and 15 min after needle removal. The same subjects also underwent a similar protocol in which, however, sham acupuncture without any needle penetration was used. RESULTS: During real acupuncture, both N1 and N2/P2 amplitudes were reduced, as compared to baseline (p<0.01). The reduction lasted up to 15 min after needle removal. Furthermore, laser pain perception was reduced during real acupuncture, although the difference was marginally significant (p=0.06). CONCLUSIONS: Our results show that abdominal acupuncture reduces LEP amplitude in healthy subjects. SIGNIFICANCE: Our results provide a theoretical background for the use of abdominal acupuncture as a therapeutic approach in the treatment of pain conditions. Future studies will have to be conducted in clinical painful syndromes, in order to confirm the analgesic effect of acupuncture in patients suffering from pain.

Ultrasound assessment of sural nerve in Charcot-Marie-Tooth 1A neuropathy.

OBJECTIVE: Nerve ultrasound (US) has been used to study peripheral nerve disease, and increase of the cross-sectional area (CSA) has been described in demyelinating polyneuropathy. The objective of the current study is to characterise the US features of the sural nerve in a sample of Charcot-Marie-Tooth (CMT) 1A patients. METHODS: A total of 20 CMT1A patients were enrolled. As control group we studied 37 age- and sex-matched subjects. All patients underwent clinical examination, neurophysiology and US evaluation of the bilateral sural nerve and right ulnar nerve. US results were correlated with neurophysiology and clinical data. RESULTS: Sural nerve CSA was not increased in the majority of patients (70%), whereas an increased ulnar nerve CSA was present in the whole sample. Inverse relations were found between CSA of the ulnar nerve and body mass index (BMI) (p<0.0002, R=-0.8) and CSA of the sural nerve and age (right 0.006, R=-0.6, left 0.002, R=-0.6 and left and right p=0.00003, R=-0.4). CONCLUSIONS: US showed ulnar CSA enlargement and normal sural nerve CSA. SIGNIFICANCE: The significance of normal sural nerve CSA in CMT1A patients need to be further investigated, possibly through longitudinal studies.

Evidence of different spinal pathways for the warmth evoked potentials.

OBJECTIVE: To investigate the presence of multiple spinothalamic pathways for warmth in the human spinal cord. METHODS: Laser evoked potentials to C-fiber stimulation (C-LEPs) were recorded in 15 healthy subjects after warmth stimulation of the dorsal midline at C5, T2, T6, and T10 vertebral levels. This method allowed us to calculate the spinal conduction velocity (CV) in two different ways: (1) the reciprocal of the slope of the regression line was obtained from the latencies of the different C-LEP components, and (2) the distance between C5 and T10 was divided by the latency difference of the responses at the two sites. In particular, we considered the C-N1 potential, generated in the second somatosensory (SII) area, and the late C-P2 response, generated in the anterior cingulate cortex (ACC). RESULTS: The calculated CV of the spinal fibers generating the C-N1 potential (around 2.5m/s) was significantly different (p<0.01) from the one of the pathway producing the P2 response (around 1.4m/s). CONCLUSIONS: Our results suggest that the C-N1 and the C-P2 components are generated by two parallel spinal pathways. SIGNIFICANCE: Warmth sensation is subserved by parallel spinothalamic pathways, one probably reaching the SII area, the other the ACC.

Levodopa effect on electromyographic activation patterns of tibialis anterior muscle during walking in Parkinson's disease.

Previous studies have reported that patients with Parkinson's disease (PD) show, in the "off medication" state, a reduced activation of tibialis anterior (TA) in the late swing-early stance phase of the gait cycle. In PD patients the pathophysiological picture may cause differences among the stride cycles. Our aims were to evaluate how frequently TA activity is reduced in the late swing-early stance phase and if there is a relationship between the TA pattern and the clinical picture. Thirty PD patients were studied 2 h after Levodopa administration ("on-med") and 12 h after Levodopa wash-out ("off-med"). They were evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS III) and surface electromyography of TA and gastrocnemius medialis (GM). The root mean square (RMS) of the TA activity in late swing-early stance phase (RMS-A) was normalized as a percent of the RMS of the TA activity in late stance-early swing (RMS-B). RMS-A was reduced in 30% of patients in the "off-med" condition. Within these patients, the percentage of stride cycles with reduced RMS-A, ranged between 28% and 83%. After Levodopa intake, no stride cycle showed reduced RMS-A. Patients with reduced RMS-A had a lower UPDRS III total score in the "on-med" rather than in the "off-med" condition (p=0.02). Our data confirm and extend previous observations indicating that, in "off-med" the function of TA is impaired in those patients clinically more responsive to Levodopa. TA activation is reduced in a relatively high percent of gait cycles in the "off-med" state. Since the variability of TA activation disappears after Levodopa administration, this phenomenon could be the expression of an abnormal dopaminergic drive.

A new clinical scale to grade the impairment of median nerve in carpal tunnel syndrome.

OBJECTIVE: In carpal tunnel syndrome (CTS) distribution of paresthesias is related to the degree of the nerve impairment. To improve the clinical ability in detecting the damage severity, we have introduced the criteria "distribution of paresthesias" in a previous clinical scale: the historical-objective scale (Hi-Ob). METHODS: We evaluated 100 consecutive patients (40 bilateral CTS) to validate a five stages clinical scale: the Historical-objective-distribution based scale (Hi-Ob-Db). We compared the Hi-Ob-Db with a validated neurophysiological classification and with the Boston Carpal Tunnel Questionnaire (BCTQ). The BCTQ evaluates two domains, one assessing symptoms (SYMPT=patient-oriented symptom), and the other analysing "functional status" (FUNCT=patient-oriented function). RESULTS: The positive correlation between the Hi-Ob-Db and neurophysiological findings (p<0.001, r:0.79) was stronger than correlation between the Hi-Ob and the neurophysiological classification (p<0.001, r:0.74). A linear correlation between the Hi-Ob-Db and the patient-oriented scores was observed, respectively FUNCT (p<0.003, r:0.38) and SYMPT (p<0.002, r:0.30). CONCLUSIONS: The Hi-Ob-Db is a clinical scale which correlates with the neurophysiological impairment of the median nerve and with patient-oriented findings in patients with CTS. SIGNIFICANCE: The new scale may be useful in routine examination and for scientific purposes.