| Focal dystonias are abnormal contractions of muscles leading to abnormal postures.The overactivity of muscles characteristic of focal dystonia is thought to be mediated by a neurophysiological disturbance in the basal ganglia and/or brainstem. Spasmodic torticollis is the most common form of focal dystonia,which had been thought as a kind of extrapyramidal diseases by most scholars.It is characterized by sustained involuntary contractions of the cervical muscles,often leading to painful and disabling neck spasms and abnormal head positions. The incidence of ST is associated with genetics, trauma, psychological, neurotransmitter disorders, sensory system dysfunction, and certain drugs and so on. But so far, there is no a theory to explain its etiology fundamentally. Drugs often used in the treatment of extrapyramidal disorders bring poor efficacy for the treatment of ST. Botulinum toxin injections for the treatment of ST broke the deadlock.Intramuscular injection with botulinum toxin can temporarily relieve spasm of neck muscles, but long-term repeated applications lead to antibody production, poor effect, and side effects. Once the conservative treatment (at least six months or more) for severe ST is invalid, surgical intervention is required. Since the pathogenesis is not clear, symptomatic treatment become the main surgical method.Different surgical approach has been taken for the treatment of ST,such as muscle resection, nerve transection, spinal nerve rhizotomy, stereotactic nucleus lesioning operation, microvascular decompression for accessory nerve, deep brain stimulation, chronic intrathecal baclofen therapy and Foerster-Dandy operation. The classical Foerster-Dandy operation is intradural section of bilateral roots of spinal accessory nerves and ventral roots of C1-4through occipital midline approach. Considering wide neck muscles are involved in ST,they did bilateral anterior root rhizotomy without distinguishing clinical types and equal denervation without distinguishing spasticity involving neck muscles.This operation sacrifice a lot of normal muscles,and increasing postoperative complications.So it may bring insufficient denervation or muscle relaxation. Basing on principles of selective partial cervical posterior rhizotomy for the treatment of upper limb spasticity in cerebral palsy, we performed selective partial cervical posterior rhizotomy to alleviate spasm for severe ST.Combined with selective partial cervical anterior rhizotomy,we can ensure curative effect, and avoid the disadvantages of all anterior rhizotomy which increase the incidence of postoperative complications.We modified this operation two times in2001and2007respectively. The purpose of this study was to investigate the effectiveness and complications of two modified Foerster Dandy operations in the treatment of ST.Methods183cases of spasmodic torticollis patients were treated by modified Foerster-Dandy’s operation from July2001to June2009,who were classified into group A and group B. Group A(126cases) was treated by firstly modified Foerster-Dandy’s operation, which was intradural section of bilateral roots of spinal accessory nerves and C1nerves,partial ventral and dorsal roots of C2,C3through occipital midline approach. Group B (57cases) was treated by secondly modified Foerster-Dandy’s operation, without resection of occipital squama and foramen magnum, intradural section of bilateral roots of spinal accessory nerves were achieved under endoscope-assistance,the other surgical steps as firstly modified Foerster-Dandy’s operation.Results All the patients were averagely followed-up for33.4months after surgery. The spasticity was relieved immediately after the operation in all the patients. The relief rate of spasticity was92.9%(117/126) and94.7%(54/57) in A and B groups respectively during the follow-up period. The spasticity recurred in9patients in group A and3patients in group B (P>0.05).Postoperative complications in group A (126patients) included transient weakness of neck, arms and shoulders in124cases, with persistent severe weakness in2cases. But there was no one with persistent severe weakness in group B(P>0.05). In group A,dysphagia of different degrees was observed in36cases, in whom, dysphagia was disappeared in18cases, significantly relieved in11, and unchanged in7during the follow-up period. In group B,dysphagia of different degrees was observed in8cases, in whom, dysphagia was disappeared in5cases, significantly relieved in2, and unchanged in1(follow-up:only one month)(P<0.05). The intracranial infection rates in A and B groups were7.9%and3.5%respectively(P<0.05). The mean operative time was also significantly shorter in group B(2±0.4hours) than that in group A (3.3±0.6hours)(P<0.05). The mean intraoperative blood loss was200ml±15ml (±standard deviation) in group A and50ml±6ml in group B(P<0.05).Conclusions Cutting off bilateral accessory roots could be performed under endoscope-assisted secondly modified Foerster-Dandy’s operation, without resection of occipital squama and foramen magnum. Given keeping the efficacy and non-increasement of nervous complications, further reduction of surgical trauma and intraoperative blood loss,decreasement of intracranial infection rate, increasement of the stability of atlanto-occipital region and significant descreasement of the incidence of other complications could be achieved. Objective Evaluate the effect of second modified Foerster-Dandy operation for the treatment of spasmodic torticollis objectively and accurately in perioperative period through neurophysiological monitoring,further improve the effect of operation, and reduce the incidence of complications.Methods40cases of severe spasmodic torticollis were analysed retrospectively, which were treated by second modified Foerster-Dandy’s operation from March2011to March2013.First,we underwent preoperative and postoperative electromyography of neck muscles (sternocleidomastoid, splenius capitis,trapezius). We judged the curative effect of this operation according to the amplitude level of action potential involving these muscles. Second,we performed intraoperative immediate stimulation for anterior and posterior roots of spinal nerves,and selectively cut the proportion of associated nerve according to the contraction and amplitude of the action potential involving corresponding muscles. Third, we monitored the functional integrity of spinal cord pathway and discovered spinal accessory injury in time through intraoperative somatosensory evoked potential (SEP).Compared with previous40cases without neurophysiological monitoring,we analysed the difference between them.Results Postoperative amplitudes of sternocleidomastoid, splenius capitis.trapezius decreased significantly than preoperative amplitudes of these muscles. The difference was statistically significant. According to direct electrical stimulation of anterior and posterior roots of spinal nerves, we selectively cut the proportion. The proportion of nerves in operation was cut as follows:100%in bilateral accessory nerves,80%-90%in anterior roots of C1,60%-75%in anterior roots of C2,10%-15%in posterior roots of C2,45-60%in anterior roots of C3,50%-70%in posterior roots of C3; All patients with SEP were successfully induced and recorded.Compared with the warning reference potential, the amplitudes of SEP in2patients decreased significantly and recovered through adjusting the operation or stopping the manipulation. All operations were performed without injury of spinal cord. Upper extremity numbness occurred in4of previous40patients without electrophysiological monitoring,and10of these40cases occured neck and shoulder pain. The difference was statistically significant.Conclusions The significant difference between preoperation and postoperation involving the related parameters in the same muscle provides the objective basis for second modified Foerster-Dandy operation in the treatment of spasmodic torticollis. Selective cutting of spinal nerves through intraoperative electrical stimulation and free recording EMG quantify the cutting proportion, avoid unnecessary injury, and reduce the incidence of complications. Intraoperative somatosensory evoked potential monitoring can effectively reduce mechanical injury of cervical cord, protect function of nerves, and improve the safety of such operation. Therefore, perioperative neural electrophysiological monitoring plays an important role in objectively assessing the curative effect of second modified Foerster-Dandy operation in the treatment of spasmodic torticollis, improving efficacy, and reducing the incidence of complications. |
PDF Full Text Request