Nerve conduction studies in multiple system atrophy

To study the frequency and severity of peripheral neuropathy in multiple system atrophy (MSA), we performed nerve conduction studies in 42 MSA patients suffering from either cerebellar MSA (MSA-C) or parkinsonian MSA (MSA-P). Abnormal nerve conduction was present in 24% of the patients. Abnormalities were significantly more frequent in MSA-P (43%) compared to MSA-C (14%). Motor nerve conduction velocities were reduced in 4% of the MSA-C and in 7% of the MSA-P patients. Abnormal compound muscle action potentials were more frequent in MSA-P (29% versus 7% in MSA-C) pointing to a more pronounced loss of motor axons in this subgroup. Sensory nerve conduction velocities were abnormal in 4% of the MSA-C and 14% of the MSA-P patients, and mean sensory nerve action potentials were normal in all MSA-C and reduced in 7% of the MSA-P patients. The data provide evidence that the peripheral nervous system is differentially affected in MSA-C and MSA-P.     

Perioral reflexes in orofacial dyskinesia and spasmodic dysphonia.

In order to assess the clinical utility of trigemino-facial reflexes in lower facial muscles, we studied perioral reflexes to mechanical and electrical stimulation in 13 patients with spasmodic dysphonia and orofacial dyskinesia and in 7 healthy subjects. Mechanical stimulation of the upper lip of all patients and electrical stimulation of the infraorbital nerve of patients with orofacial dyskinesia elicited larger perioral reflexes than in controls. In the majority of patients, hyperexcitable perioral reflexes were accompanied by increased gain of the blink reflex. In 4 patients, however, trigemino-facial reflexes were enhanced selectively in either the perioral muscles or orbicularis oculi. Our findings suggest that the quantitative assessment of perioral reflexes may provide information about the excitability of brainstem interneurons in cranial dystonia that is complementary to blink reflex studies.     

Prevalence of hepatitis B in haemodialysis nursing staff in athens

Background: Healthcare workers are at high risk of acquiring hepatitis B and particularly haemodialysis staff. The aim of the study was to examine the prevalence of hepatitis B markers in haemodialysis nurses and to explore the determinants of the infection. Patients and methods: Two hundred and sixteen haemodialysis nurses from 20 haemodialysis units in Athens completed an anonymous questionnaire, their blood samples were taken and tested for hepatitis B virus (HBV) markers. Results: The prevalence of positive HBsAg among nurses was 0.5%. Anti‐HBc positivity due to past exposure to HBV was 12.5%. A total of 87.5% of the participants had immunity to HBV. Multivariate analysis demonstrated that previous exposure to HBV was related positively with the age of the haemodialysis nursing staff [odd ratios (OR): 1.115, 95% CI: 1.014–1.226, P = 0.025]. Conclusion: The prevalence of HBV in the haemodialysis nursing staff in Athens is low, the vaccination coverage and the immunity to HBV are high in comparison to previous reports.     

Multijoint arm movements in cerebellar ataxia: Abnormal control of movement dynamics

In cerebellar ataxia, kinematic aberrations of multijoint movements are thought to originate from deficiencies in generating muscular torques that are adequate to control the mechanical consequences of dynamic interaction forces. At this point the exact mechanisms that lead to an abnormal control of interaction torques are not known. In principle, the generation of inadequate muscular torques may result from an impairment in generating sufficient levels of torques or from an inaccurate assessment and prediction of the mechanical consequences of movements of one limb segment on adjacent joints. We sought to differentiate the relative contribution of these two mechanisms and, therefore, analyzed intersegmental dynamics of multijoint pointing movements in healthy subjects and in patients with cerebellar degeneration. Unrestrained vertical arm movements were performed at three different target movement velocities and recorded using an optoelectronic tracking system. An inverse dynamics approach was employed to compute net joint torques, muscular torques, dynamic interaction torques and gravitational torques acting at the elbow and shoulder joint. In both groups, peak dynamic interaction forces and peak muscular forces were largest during fast movements. In contrast to normal subjects, patients produced hypermetric movements when executing fast movements. Hypermetric movements were associated with smaller peak muscular torques and smaller rates of torque change at elbow and shoulder joints. The patients’ deficit in generating appropriate levels of muscular force were prominent during two different phases of the pointing movement. Peak muscular forces at the elbow were reduced during the initial phase of the movement when simultaneous shoulder joint flexion generated an extensor influence upon the elbow joint. When attempting to terminate the movement, gravitational and dynamic interaction forces caused overshooting extension at the elbow joint. In normal subjects, muscular torque patterns at shoulder and elbow joint were synchronized in that peak flexor and extensor muscular torques occurred simultaneously at both joints. This temporal pattern of muscular torque generation at shoulder and elbow joint was preserved in patients. Our data suggest that an impairment in generating sufficient levels of phasic muscular torques significantly contributes to the patients’ difficulties in controlling the mechanical consequences of dynamic interaction forces during multijoint movements. Received: 28 October 1996 / Accepted: 30 September 1997     

Idarucizumab administration in emergency situations: the Munich Registry of Reversal of Pradaxa® in clinical routine (MR REPAIR)

Journal of Neurology - To evaluate daily life management and functional outcome of Idarucizumab administration in case of emergency situations in patients with Dabigatran treatment. Multicenter...     

Leg paresthesias induced by magnetic brain stimulation in patients with thoracic spinal cord injury

We studied the induction of leg paresthesias by magnetic stimulation of the brain in seven patients with thoracic T9-12 spinal cord injury and in four normal volunteers by delivering transcranial magnetic stimulation over scalp positions 1 cm apart with a Cadwell MES-10 magnetic stimulator and an 8-shaped magnetic coil at 100% stimulus intensity. We asked subjects to report sensations felt after each stimulus. In all normal subjects, magnetic stimulation evoked sensations described as tingling or a wave descending along the leg, usually accompanied by EMG responses in leg muscles. In three of the seven patients, stimulation evoked sensations of tingling, numbness, touch, or a wave descending along the leg, lasting up to 10 seconds and referred to different parts of the legs and toes. In the patients, sensations were felt more distally the closer the site of stimulation was to the midline. Patients with leg paresthesias had less motor reorganization in abdominal muscles than those without paresthesias. These findings suggest that portions of the cortical representation areas for body parts deafferented by a complete spinal cord injury can remain related to those body parts for up to several years. A central origin of these paresthesias is probable.     

Disturbances of grip force behaviour in focal hand dystonia: evidence for a generalised impairment of sensory-motor integration?

BACKGROUND: Focal task specific dystonia occurs preferentially during performance of a specific task. There may be an inefficiently high grip force when doing manipulative tasks other than the trigger task, possibly reflecting a generalised impairment of sensory-motor integration. OBJECTIVE: To examine how well subjects with writer's cramp (n = 4) or musician's cramp (n = 5) adapted their grip force when lifting a new object or catching a weight. METHODS: Nine patients with focal hand dystonia and 10 controls were studied. Experiments addressed different motor behaviours: (A) lifting and holding an object; (B) adjusting grip force in anticipation of or in reaction to a change in load force by catching a small weight dropped expectedly or unexpectedly into a hand held receptacle. RESULTS: In (A), patients produced a grip force overshoot during the initial lifts; force overflow was most pronounced in those with writer's cramp. Patients and controls adjusted their grip force to object weight within one or two lifts, though patients settled to a steady force level above normal. In (B), patients with focal hand dystonia and normal controls showed similar predictive grip force adjustments to expected changes in object load, suggesting that this aspect of sensory-motor integration was normal. Patients had a shorter latency of grip force response than controls after an unexpected load increase, reflecting either a greater level of preparatory motor activity or a disinhibited spinal reflex response. CONCLUSIONS: The overall increased grip force in patients with focal hand dystonia is likely to be a prelearned phenomenon rather than a primary disorder of sensory-motor integration.     

Impaired generalization of weight-related information during grasping in cerebellar degeneration

When we repetitively lift an object, the balance between grip force normal to the object's surface and load force tangential to the object's surface is accurately programmed to match the physical object properties within a few lifts. Here, we ask if the accuracy of grip force scaling to object weight and the transfer of weight-related information from one hand to the other is impaired in cerebellar degeneration. Subjects with generalized cerebellar degenerative disorders were tested. Subjects first repeatedly lifted a constant weight with the dominant hand, followed by a series of lifts of the same weight with the opposite hand. The experiments were performed with a light and a heavy weight. Patients and controls scaled the grip force output differentially to different weight. The comparison of grip force scaling for the first and last lifts with a constant weight demonstrated that healthy subjects and cerebellar patients adjusted grip forces more accurately to a specific weight with increasing number of lifts performed at each hand. The ability to transfer weight-related information from one hand to the other was analyzed by comparing the last lift with a constant weight of the dominant hand with the first lift of the same weight performed by the opposite hand. Healthy subjects scaled the grip force output precisely to a given weight immediately after a change in hand, suggesting that they succeeded to transfer weight-related information in between both hemispheres. In contrast, cerebellar patients produced an inaccurate grip force overshoot when lifting a given weight with the opposite hand. Our data suggest that the cerebellum plays a major role for the generalization of weight-related information during object manipulation.