The Electrophysiological Study On Cervical Dystonia And Essential Head Tremor And Gene Polymorphisms On Cervical Dystonia

Backgrounds: Cervical dystonia (CD) is characterized by sustained or intermittent contractions of neck muscles, causing twisting and repetitive movements or abnormal posture of the head. The frequency of hand, arm, and head tremor in CD patients has been reported to be 3-80%. It is uncertain whether head tremor in CD is part of the dystonia or part of a coexisting essential tremor, which is a common movement disorder. There are some symptoms: (l)TCD(tremulous CD) or cervical dystonia with tremor, (2) DHT(dystonic head tremor), without obvious deviations, (3)EHT(essential head tremor). DHT and EHT are similar in clinical manifestations. When there is no positive family history and show no reaction to the alcohol and medicine, the diagnosis is more difficult. Researches show some cases which the main symptoms of head tremor progress into dystonia in the end. In the pathology of the brain, they have not found the focus that relate with dystonia, and CT MRI do not show the abnormality in the basal ganglia. In the recent more than 10 years, because the rapid progress in the neurophysiology, functional imaging and electrophysiology, special in motor evoked potential and electromyography, we can make further research into the pathogenesis of dystonia. The treatment includes etiology, medicine, botulinum and surgery. But because of the adverse effects and traumatic occlusion, the reachers are reaching for the new treatment. Transcranial magnetic stimulation is not only used in diagnosis of many diseases, but also in the treatment recently.Objective: To analysis the clinical display and electrophysiological research, compare the manifestation of cervical dystonia with and withouout heard tremor and essential head tremor, whether there are differences in electromyography, MEP, andthe differences in pathogenesis. To investigate the possible association between dopamine D2 receptor(DRD2) genotypes and cervical dystonia and the therapeutic effects of low frequency repetitive transcranial magnetic stimulation in cranial dystonia.Methods: We prospectively evaluated clinical characteristics, natural history, electromyography and motor evoked potentials of patients with cervical dystonia(CD) and ET patients. Chi-square and ANOVA were employed for statistical analysis. Dystoina patients were treated with low frequency rTMS. Before and after the rTMS treatment we evaluated the patients by motor threhold, central silent period (CSP) and after 1 month, 2 month evaluated the spams Tusi, TWSTRS, to evaluate the effects of rTMS in the treatment of cranial dystonia. PCR-RFLP was used to perform genotyping on DRD2 from cervical dystonia and healthy controls. Results:1. There is higher prevalence of head tremor in women in HT(+) and ET than in HT(-), there is a special gestes antagonists in CD. 56.1% of patients in HT(+) have tremor as one the first symptoms, the only symptom in 7% patients. CD will appear following head tremor after 4.89 years. 26.7% of CD patients have also hand tremor, ET have hand tremor, higher than HT(+) (P=0.005). HT(-) have the lowerest positive family history and 37.5% of ET have the highest family history.2. The EMG manifestations of the dystonia patients show irregular grouping voltages with a frequency of 5.4-5.9Hz, while EHT shows regular grouping voltages with a frequency of 4.7Hz at rest. These are typical manifestations in spasmodic muscles. The patients show the prolonged MUP, increased the phase than the control (P<0.05). During maximum contraction turns/sec and ratio are reduced. There are also difference between dystonia and ET.3. In the 4 groups of patients, the CSP of CD groups is 91.5-103.2ms significantshorter than the EHT's CSP is 135.8ms (PO.05), the motor threshold of only CD group is the lowest, while the EHT groups have the highest motor threshold, but there is no statistical significance(P>0.05). There was a very significant prolongation of CSP and higher motor threhold than before treatment. The patients scored significantly lower on Tsui and TWSTRS after 1 and 2 month( P <0.05).But there is a tendency of increasing on the score after 2 month, but the pain score in the TWSTRS was not reduced significantly.4. There were no statistically significant differences in the distribution of DRD2 A and B alleles and genotypes between dystonia cases and controls.Conclusions:1. Head tremor is common in CD and is more commonly associated with hand tremor and family history of tremor or other movement disorders.2. That EMG manifestations show central nervous systems—spinal cord, brain stem or motor cortex abnormal activities. The frequency of grouping voltage at rest and manifestation of EMG do help to differentiate the EHT and the cervical dystonia without obvious deviation during the early phase.3. The CD and EHT can be differentiated by the different display of the motor evoked potential.4. The low frequency rTMS is efficient to relieve the clinical symptoms of cranial dystonia. It may enhance the intracortical inhibition(ICI), prolong the CSP. The clinical symptoms are apparently alleviated after 1 month, yet the long term effect of rTMS needs further studying.5. There may be no association between polymorphisms TaqI A and B site at DRD2 gene and genetic susceptibility of cervical dystonia.