| Background:The pathogenesis of spasmodic torticollis(ST) is still uncertain. Recently it has been very active to study on the pathogenesis.It has been reported by Amit Agrawal that the destruction of the monkey's brain stem cross-department integration arm,,medial longitudinal fasciculus and the medial reticular formation can lead to torticollis. Amit Agrawal reported that a 9-year-old female child developed acute torticollis because of the hemorrhage in brain stem cavernoma. These reports indicate that the function of brainstem is closely related to torticollis. By meams of 3T fMRI Paulien M. de Vries found that cervical dystonia was associated with patterns of abnomal cerebral activation and these patterns included parietal cortices,cingulated cortex/SMA and putamen. These literatures prompted us to pay more attention to the function of the brainstem and cerebral cortex in patients with torticollis. Brainstem reflex and somatosensory evoked potential are important tools to elucidate the pathogenesis of spasmodic torticollis. At prsent,Foreign countries have carried out the study of individual brain stem reflex and somatosensory evoked potential, Com-prehensive study has not been reported..Brainstem reflex and somato-sensory evoked potential in patients with torticollis have not carried out interiorly. Since the central section of trigeminal-cerical reflex is in the lower pons, ventromedial medulla and cervical spinal cord; the central section of blink reflex is in the lateral of upper medulla and pons; the central section of brain stem auditory evoked potential is in Pons and midbrain, comprehensive study of the three brainstem can reflect how brain stem and cervical spinal cord impact on the spasmodic torticollis. Objectives:To futher elucidate the pathogenesis of spasmodic torticollis.Methods:1.Somatosensory evoked potential was investigated in 30 patients affected ST and 30 normal subjects. Bilateral N20, P27,N35,P22,N30 Latency and P22/N30 amplitude could be recorded after stimulation of median nerve in 30 patients affected ST, P22/N30 amplitude could be recorded after stimulation of median nerve in 30 normal subjects while their head turned to right.2.Brainstem auditory evoked potential was investigated in 30 patients affected ST and 30 normal subjects.â… -â…¢,â…¢-â…¤Interpeak latencies (IPLs) andâ… /â…¤amplitude ratio was compared between Ipsilateral to torticollis and contralateral to torticollis in 30 patients with ST,â… -â…¢IPLs,â…¢-â…£IPLs andâ… /â…¤amplitude ratio was compared between the left and right sides in 30 normal subjects.3.Blink reflex was investigated in 30 patients affected ST and 30 normal subjects. Latency and amplitude of R1,R2 was compared between Ipsilateral to torticollis and contralateral to torticollis in 30 patients with ST. Latency and amplitude of R1,R2 was compared between the left and right sides in 30 normal subjects.4.Trigeminal-cerical reflex was investigated in 12 patients affected ST. P19 latency was compared between Ipsilateral to torticollis and contra-lateral to torticollis.Results:1.All ST patients presented normal latency of N20,P27,N35,P22,N30, Ipsilateral latency and contralateral latency are not different from each other in statistics.An apparent mean P22/N30 amplitude increase was found above the hemisphere contralateral to the direction of head deviation. The mean side-to-side ratio of the precentral P22/N30 component amplitude was not different in heathy control subjects.2.All ST patients presented normalâ… -â…¢,â…¢-â…£IPLs. Ipsilateralâ… -â…¢IPLs were greater in patients thanâ… -â…¢IPLs contralateral to torticollis. Meanâ…¢-â…¤IPLs andâ… /â…¤amplitude ratios did not differ significantly between ipsilateral to torticollis and contralateral to torticollis. Meanâ… -â…¢ IPLs andâ… /â…¤amplitude ratios did not differ significantly between the left and right sides in 30 normal subjects.3. All ST patients presented normal R1,R2 latency and R1 amplitude, No significant difference was found between ipsilateral to torticollis and contralateral to torticollis. Ipsilateral R2 amplitude was greater in patients than R2 amplitude contralateral to torticollis. R1,R2 latency and R1,R2 amplitude did not differ significantly between the left and right sides in 30 normal subjects.4. All ST patients presented abnormalities of TCR at least one side, Bilateral P19 latency difference was greater than 2 seconds. A bilateral positive/negative wave was absent at the stemocleidomastoid muscles res-ponses contralateral to torticollis in one patient.Conclusions:1. By the means of SEPs normal latency of N20,P27,N35,P22,N30 indicate that the structure of pathway is normal.That the mean value of the P22/N30 amplitude contralateral to head deviation was significantly higher supported the conclusion that this abnormality could be a heightened excitability of the cortical region that generates the P22/N30 complex and the N30 peak registered in the precentral corticalarea in the hemisophere contralateral to the direction of head deviation. That N30 may be from Supplementary motor area indicate that ST patients may have faulty pro-cessing within the lemniscal pathway with abnormalities in the sensory-motor integration.2. By the means of BAEP, normalâ… -â…¢,â…¢-â…¤IPLs indicate that the structure of upper brain stem pathway is normal. That ipsilateralâ… -â…¢IPLs were greater in patients thanâ… -â…¢IPLs contralateral to torticollis indicate that brain-stem dysfunction ipsilateral to head deviation.3. By the means of BR, normal R1,R2 latency indicate that the structure of reflex arc is complete,That ipsilateral R2 amplitude was greater in patients than R2 amplitude contralateralto torticollis indicate that increases exci-tability of brainstem interneuronal pathways mediated the R2 com-ponent.4.That all ST patients presented abnormalities of TCR at least one side indicate that the lower pons, ventromedial medulla and cervical spinal cord pathway is abnormal and support that ST patients may have faulty processing within the lemniscal pathway with abnormalities in the sensory-motor inte gration.
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