Abnormal sensorimotor integration is related to disease severity in Parkinson's disease: a TMS study.

Hyperexcitability of the motor system has been reported in Parkinson's disease (PD). We evaluate how cutaneous afferents modulate motor excitability in PD patients and whether abnormal modulation is correlated to parkinsonian symptoms. Digital stimulation causes abnormal enhancement of motor responses in patients. This effect may be one of the features of motor hyperexcitability in PD. Cutaneomotor hyperexcitability correlates with clinical scores, suggesting that abnormal processing of cutaneous inputs might contribute to the pathogenesis of parkinsonian symptoms.     

Functional role and histological demonstration of nitric-oxide-mediated inhibitory nerves in dog sphincter of Oddi

Abstract Nitric oxide (NO) plays an important physiological role in regulating gastrointestinal motility. Involvement of endogenous NO was evaluated in the response to non-adrenergic, non-cholinergic (NANC) nerve stimulation of the dog sphincter muscle of Oddi. Transmural electrical stimulation (TES), nicotine (10^?5M) and K⁺ (10 mM) produced only a relaxation in the sphincter muscle strips contracted with substance P, which was not potentiated by atropine. The TES-induced relaxation was abolished by tetrodotoxin (3 times 10^?7 M) and oxyhaemoglobin (1.6 times 10^?5 M), but not affected by atropine (10^?7 M), propranolol (10^?7 M), phentolamine (10^?7 M), indomethacin (10^?6 M), chole-cystokinin (CCK, 10^?8 M) and vasoactive intestinal polypeptide (VIP, 10^?8 M). The relaxation was also abolished by treatment with N^G-nitro-L-arginine (L-NA, 10^?5 M), an NO synthase inhibitor. Nicotine produced a transient relaxation, which was abolished by tetrodotoxin, hexamethonium (10^?5 M) and L-NA, but not affected by atropine and N^G-nitro-D-arginine (D-NA, 10^?5 M). The addition of K⁺ elicited a transient relaxation, which was abolished by tetrodotoxin and L-NA. The inhibitory effects of L-NA were antagonized by L-arginine (10^?3 M). The presence of neurons containing nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase was histochemically demonstrated in the sphincter of Oddi. These findings may indicate that TES, nicotine and K⁺ liberate NO from NANC inhibitory nerve which is involved in the relaxation of the dog sphincter of Oddi. The muscular tone does not seem to be regulated by cholinergic nerves under the experimental conditions used.     

VIM thalamic stimulation for tremor in a patient with IgM paraproteinaemic demyelinating neuropathy.

We demonstrate the effect of deep brain stimulation of the ventral intermediate thalamic nucleus on intractable action tremor, in a 72-year-old man suffering from neuropathy associated with monoclonal gammopathy.     

Primary orthostatic tremor is an exaggeration of a physiological response to instability.

Primary orthostatic tremor (POT) is a rare disorder characterised by an intense sense of unsteadiness upon standing and a 16-Hz tremor in which the timing between tremor bursts in different muscles (unilateral and bilateral) remains constant. Hitherto, similar EMG activity has not been described in healthy subjects and it has been postulated that the oscillations seen in POT are primarily pathological. In this study, EMG was recorded from tibialis anterior in healthy subjects who were made unsteady through vestibular galvanic stimulation or leaning backwards. Under these conditions, a peak at approximately 16 Hz was seen in the coherence between the left and right tibialis anterior. This bilateral coherence was absent when the subjects activated the same muscles when not unsteady. These data indicate the existence of a physiological system involved in organising postural responses under circumstances of imbalance and characterised by a highly synchronised output at approximately 16 Hz. In addition, the results suggest that the core abnormality in POT may be an exaggerated sense of unsteadiness when standing still, which then elicits activity from a 16-Hz oscillator normally engaged in postural responses.     

Pain-related somatosensory evoked potentials following CO2 laser stimulation in peripheral neuropathies

Pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation were examined in 30 patients with peripheral neuropathies, and the results were compared with clinical sensory findings. Pain SEP findings showed a significant correlation with the clinical impairment of pain sensation, but not with the impairment of deep sensations. In contrast, conventional electrically-stimulated SEPs (electric SEPs) showed a significant correlation with deep sensations, but not with the impairment of pain sensation. Examinations of both pain SEPs and electric SEPs, therefore, are considered to be very useful to evaluate physiological functions of sensory nerves in patients with peripheral neuropathies.     

电刺激黑质对脑干伤害性单位放电的影响

本实验采用单细胞外记录神经元单位放电的方法，在Ｗｉｓｔａｒ大鼠上观察到网状巨细胞核。一区伤害性神经元５７个，其中伤害兴奋性神经元（ＮＥＮ）４２个，伤害抑制性神经元（ＮＩＮ）１５个。电刺激黑质对ＮＥＮ（２９）和ＮＩＮ（８的放电呈抑制作用，其反应百分率分别由刺激黑质第１分钟时的１．０±２．１％和－２０．４±６．２％，降到第５分钟时的－８３．６±１２．３％和－６５．４±１０．７％（Ｐ＜０．０１）。刺激黑质对少数ＮＥＮ（１３）和ＮＩＮ（７）的放电有兴奋作用，其值分别由第］分钟时的２０．５±７．３％和１．０±３．４％，升高到第５分钟时的７４．５±１０．７％和２１，５±８．６％（Ｐ＜０．０５）。氟哌啶醇注入ＰＡＧ腹外侧部可阻断刺激黑质的效应，这提示从黑质到网状巨细胞核α－区存在着一条痛调制通路，而且这种通路的递质是多巴胺能的。     

Change in urethral pressure during voluntary pelvic floor muscle contraction and vaginal electrical stimulation

The purpose of the study was to compare the effect of voluntary pelvic floor muscle (PFM) contraction and vaginal electrical stimulation on urethral pressure. Twelve women with genuine stress incontinence, mean age 49.4 years (range 33–66) participated in the study. The urethral and bladder pressures were recorded simultaneously through a double-lumen 8 Ch catheter. The patients first performed three voluntary PFM contractions. Then two electrical stimulators, Conmax and Medicon MS 105, 50 Hz, were used in random order. A visual analog scale was used to measure pain and discomfort. Pain was reported to mean 6.8, SEM 0.64 (range 0.7–9.9) and mean 6.1, SEM 0.81 (range 0–9.1) with Conmax and Medicon MS 105, respectively. The mean paired difference in favor of voluntary contraction with Conmax was ?8.0, SD 6.7,P=0.0067, and with Medicon MS 105 it was ?12.2, SD 5.9,P=0.0022. The results demonstrated that voluntary PFM contraction increased urethral pressure significantly more than did vaginal electrical stimulation.     

Effects of synchronization in the pacemaker during high-frequency atrial stimulation

I. M. Sechenov Medical Academy, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 5, pp. 454–456, May, 1991.