Corticomotor excitability in drug-naive patients with Parkinson disease.

BACKGROUND AND PURPOSE: This study aimed to assess the indices of corticomotor excitability (CE) in drug-naive Parkinson disease (PD) patients and to investigate its relationship with asymmetry and severity of clinical symptoms. MATERIAL AND METHODS: Eleven (4 men) drug-naive PD patients (mean age: 53.1 ± 9.8 years) and 13 (7 men) healthy controls (mean age: 51.7 ± 4.2 years) were included. All PD patients were rated on the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS) with measurement of the side-specific score separately for arms and legs. Resting motor threshold (RMT), central silent period (CSP), amplitude of motor evoked potential (MEP) and central motor conduction time (CMCT) evoked by a single pulse of the transcranial magnetic stimulation were recorded in all subjects from the left and right abductor digiti minimi (ADM) and extensor digitorum brevis (EDB). RESULTS: Parkinson disease patients showed higher MEP (1.8 ± 0.9 vs. 1.1 ± 0.8 mV, p < 0.05) and shorter CMCT (6.1 ± 0.9 vs. 7.4 ± 1.0 ms, p < 0.05) recorded from the ADM on the more affected side. CSP recorded from the more affected ADM was under the normal range in five and from the less affected ADM in four PD patients. For CSP recorded from the EDB, respective values are four for the more affected side and three for the less affected side. The rigidity from the more affected arm and leg correlated negatively with the respective CSP recorded from the ADM (r = -0.74, p < 0.01) and EDB (r = -0.68, p < 0.04). CONCLUSIONS: In the early stage of untreated PD the CE parameters are altered only on the more affected side. The shortening of CSP reflects the severity of rigidity on the more affected side.

Safety of nerve conduction studies in patients with implantable cardioverter-defibrillators.

OBJECTIVE: A patient with an implantable cardioverter-defibrillator (ICD) may suffer from neuromuscular disorders and may need to undergo a nerve conduction study (NCS). However, a NCS may be a source of electromagnetic interference (EMI). The aim of the present study was to investigate whether the interference from NCS used in a standardised test protocol affects ICD function. METHODS: Twenty patients (19 males; mean age of 59.8±9.9 years) with implantable ICDs (eight with integrated and 12 with true bipolar leads), treated with amiodarone and with symptoms suggesting neuropathy were included. NCS were conducted using repetitive stimulation with frequency of 2 Hz and single, rectangular pulses of intensity up to 100 mA. Stimulation was performed in standard sites including proximal sites in the arm. RESULTS: The impulses generated NCS were not detected by the ICD, irrespective of the site, rate or stimulus intensity. CONCLUSIONS: Standardised test protocol for an NCS is safe in patients with an ICD regardless of the leads type. SIGNIFICANCE: Current guidelines which limitate the NCS in patients with ICD may be the subject of revision.

[The diagnostic and therapeutic application of transcranial magnetic stimulation]. / Przezczaszkowa stymulacja magnetyczna w diagnostyce i terapii choroby Parkinsona.

The functional abnormalities of the central motor structures and its contribution of rigidity, tremor and bradykinesia in Parkinson's disease seem mainly due to the degeneration of the nigro-striatal pathway. Transcranial magnetic stimulation (TMS) of the motor cortex may provide useful data on the pathophysiology of motor dysfunction in Parkinson's disease. Recent reviews on the basic mechanisms of TMS in Parkinson's disease show reduced inhibitory motor network at the cortical and spinal level. The observed changes are thought to be in relation with a dysfunction of subcortico-cortical and subcortico-spinal pathways. The abnormalities of the central motor function seem to be modified by several clinical related factors as prevalence of cardinal Parkinson's disease signs (e.g. rigidity versus tremor or bradykinesia), L-dopa therapy ('on/off' states) and laterality of the Parkinson's disease signs. Observations made using TMS give new pathophysiological insights in functioning of the central motor structures in Parkinson's disease and started new form of TMS - repetitive TMS (rTMS) as a treatment of the Parkinson's disease motor signs. A few studies using rTMS with repetition rate of 0.2, 1, and 5 Hz showed improvement of motor signs in the Parkinson's disease patients. Although these results support the beneficial effects of rTMS on parkinsonian symptoms, long-term studies with large numbers of subjects should be conducted to assess the efficacy of the rTMS on Parkinson's disease in future.

[Spinocerebellar ataxias type 1 and 2: comparison of clinical, electrophysiological and magnetic resonance evaluation]. / Ataksja rdzeniowo-mózdzkowa typu 1 i 2 - porównanie oceny klinicznej, elektrofizjologicznej i rezonansu magnetycznego.

BACKGROUND AND PURPOSE: Spinocerebellar ataxias type 1 (SCA1) and type 2 (SCA2) belong to neurodegenerative disorders of autosomal dominant inheritance, genetically and clinically heterogeneous, caused by the expansion of CAG trinucleotides. Trunk and limb ataxia, dysarthria, dysphagia, gaze palsy, sensory and motor axonal neuropathy are the dominant features in both entities. The aim of the study was to evaluate the differences between genotype and phenotype based on clinical and electrophysiological assessment of the visual, auditory pathways, and EEG alterations in comparison with the cerebellar and brain atrophy in MRI. MATERIAL AND METHODS: 44 patients with SCA1 and 24 cases with SCA2 confirmed molecularly were examined neurologically and using the International Cooperative Ataxia Rating Scale (ICARS). A correlation of clinical symptoms and signs, and CAG repeat numbers with EEG, visual (VEP) and brainstem auditory (BAEP) evoked potentials, and MRI alterations were evaluated. RESULTS: A statistically significant negative correlation between the age of disease onset and number of CAG repeats in both types of SCA was found. Examined patients with SCA2 were younger, with longer disease duration and more pronounced cerebellar and brain atrophy in MRI. We found a significant correlation between ICARS and CAG repeats in this group. The dysphagia, pyramidal tract involvement and depressive reaction were significantly frequent in SCA1 patients. However in SCA2 patients, the peripheral nerve damage and extrapyramidal signs were more prominent. The amplitude of P100 visual evoked potentials was significantly lower in SCA1 patients and negatively correlated with CAG repeats. CONCLUSIONS: These results provide further evidence for the phenotypic differences of genetically defined SCA1 and SCA2 patients, expressed by more frequent involvement of the pyramidal tract and depression reaction in SCA1, in contrast to peripheral nerve involvement and extrapyramidal signs in the clinical feature of SCA2 phenotype. Furthermore, atrophy of the brain and cerebellum revealed in MRI was more pronounced than electrophysiological functional alterations, especially in SCA2. The decreased amplitude of P100 VEP in SCA1 patients was the only electrophysiological parameter differentiating between both groups of patients.

Impairment of the peripheral nervous system in Creutzfeldt-Jakob disease.

BACKGROUND: The clinical manifestations of Creutzfeldt-Jakob disease (CJD) primarily reflect involvement of the central nervous system. The coexistence of CJD with peripheral nervous system involvement has also been reported. OBJECTIVE: To analyze peripheral neuron electrophysiologic changes and to compare these data with neuropathologic features of spinal motor neurons in patients with definite CJD. DESIGN AND PATIENTS: Electrophysiologic examinations were performed on 16 patients with sporadic CJD. The diagnosis was confirmed by neuropathologic examinations (15 patients) or by intravital detection of the 14-3-3 protein in the cerebrospinal fluid (1 patient). The spinal cord was neuropathologically examined in 8 patients. SETTING: Department of Clinical Neurophysiology, I Neurological Department, Institute of Psychiatry and Neurology, Warsaw, Poland. MAIN OUTCOME MEASURES: Electromyography, compound muscle and sensory nerve action potentials, distal latencies, F waves, peripheral motor and sensory conduction velocity, and spinal motor neuron numbers and morphologic characteristics. RESULTS: All patients had signs of central nervous system damage typical of sporadic CJD. Only 3 patients had clinical signs of peripheral nervous system involvement. Electrophysiologic examinations confirmed peripheral nervous system damage in these patients and revealed preclinical peripheral nervous system impairment in 11 more patients. In 1 patient, electrophysiologic examination revealed features of motor neuron disease; in 9, axonal disease; and in 4, axonal-demyelinating neuropathy. Neuropathologic examination results confirmed severe loss of spinal motor neurons in 1 patient with motor neuron disease and revealed the features of motor neuron chronic disease in 4. In 2 of them, electrophysiologic data were normal. CONCLUSION: In sporadic cases of CJD, peripheral nervous system impairment should be considered to be an integral component of disease.