Physiology of midbrain head movement neurons in cervical dystonia.

BACKGROUND: Early theories for cervical dystonia, as promoted by Hassler, emphasized the role of the midbrain interstitial nucleus of Cajal. Focus then shifted to the basal ganglia, and it was further supported with the success of deep brain stimulation. Contemporary theories suggested the role of the cerebellum, but even more recent hypotheses renewed interest in the midbrain. Although the pretectum was visited on several occasions, we still do not know about the physiology of midbrain neurons in cervical dystonia. METHODS: We analyzed the unique database of pretectal neurons collected in the 1970s and 1980s during historic stereotactic surgeries aimed to treat cervical dystonia. This database is valuable because such recordings could otherwise never be obtained from humans. RESULTS: We found the following 3 types of eye or neck movement sensitivity: eye-only neurons responded to pure vertical eye movements, neck-only neurons were sensitive to pure neck movements, and the combined eye-neck neurons responded to eye and neck movements. There were the 2 neuronal subtypes: burst-tonic and tonic. The eye-neck or eye-only neurons sustained their activity during eccentric gaze holding. In contrast, the response of neck-only and eye-neck neurons exponentially decayed during neck movements. CONCLUSIONS: Modern quantitative analysis of a historic database of midbrain single units from patients with cervical dystonia might support novel hypotheses for normal and abnormal head movements. This data, collected almost 4 decades ago, must be carefully viewed, especially because it was acquired using a less sophisticated technology available at that time and the aim was not to address specific hypothesis, but to make an accurate lesion providing optimal relief from dystonia. © 2017 International Parkinson and Movement Disorder Society.

Chronic Spinal Cord Stimulation in the Treatment of Cerebral and Spinal Spasticity.

OBJECTIVES: The aim of this investigation is to assess the effectiveness of spinal cord stimulation (SCS) in different groups of patients with spasticity of different origin. MATERIALS AND METHODS: A retrospective study of the use of the method of SCS in 71 patients. The patient population was divided into two groups: 52 cerebral palsy (CP) cases and 19 patients diagnosed with spasticity caused by spinal injury. The mean age was 7.14 ± 4.06 and 35.68 ± 12.42 years, respectively. The CP group included 41 cases of paraparesis and 11 cases tetraparesis. One quadripolar electrode was implanted into the posterior epidural space at Th10-Th12 level and an implantable pulse generator (Itrel3, Medtronic) was placed in a standard fashion. We performed 3-5 stimulation sessions per day; each lasted 30 min. The stimulation parameters were as follows: rate 100-130 Hz, pulse width 120-300 ms, amplitude 1.5-4 V. The follow-up ranged from 2 to 9 years. RESULTS: Decrease in muscle tone was observed in all cases in the group of patients with spinal spasticity: from 3.71 ± 0.61 on the Ashworth scale before the operation to 2.26 ± 0.56 after the operation (p < 0.001). In the group of cerebral spasticity a significant decrease in muscle tone was observed only in patients with spastic lower paraparesis: from 3.36 ± 0.41 before the operation to 1.97 ± 0.91 after the operation (p < 0.005). In patients with spastic tetraparesis we did not observe any significant change in muscle tone. In 8 cases we discontinued the therapy several years after the procedure due to improvement in spasticity: in the CP group in 7 cases and in 1 spinal spasticity case, where SCS systems were explanted. CONCLUSION: Chronic SCS may be a method of choice for patients with moderate spinal and cerebral spasticity with predominant spastic lower paraparesis. In patients with spastic tetraparesis SCS therapy did not prove to be effective. We encountered improvement of the spasticity and no need for further SCS therapy in a small group of patients (11%). This phenomenon requires further investigation. © 2015 S. Karger AG, Basel.