Eye movements of the murine P/Q calcium channel mutant Tottering, and the impact of aging

Mice carrying mutations of the gene encoding the ion pore of the P/Q calcium channel (Cacna1a) are an instance in which cerebellar dysfunction may be attributable to altered electrophysiology and thus provide an opportunity to study how neuronal intrinsic properties dictate signal processing in the ocular motor system. P/Q channel mutations can engender multiple effects at the single neuron, circuit, and behavioral levels; correlating physiological and behavioral abnormalities in multiple allelic strains will ultimately facilitate determining which alterations of physiology are responsible for specific behavioral aberrations. We used videooculography to quantify ocular motor behavior in tottering mutants aged 3 mo to 2 yr and compared their performance to data previously obtained in the allelic mutant rocker and C57BL/6 controls. Tottering mutants shared numerous abnormalities with rocker, including upward deviation of the eyes at rest, increased vestibuloocular reflex (VOR) phase lead at low stimulus frequencies, reduced VOR gain at high stimulus frequencies, reduced gain of the horizontal and vertical optokinetic reflex, reduced time constants of the neural integrator, and reduced plasticity of the VOR as assessed in a cross-axis training paradigm. Unlike rocker, young tottering mutants exhibited normal peak velocities of nystagmus fast phases, arguing against a role for neuromuscular transmission defects in the attenuation of compensatory eye movements. Tottering also differed by exhibiting directional asymmetries of the gains of optokinetic reflexes. The data suggest at least four pathophysiological mechanisms (two congenital and two acquired) are required to explain the ocular motor deficits in the two Cacna1a mutant strains

Anterior cervical discectomy and fusion in the era of motion preserving surgery: A retrospective study

Background. Anterior cervical discectomy and fusion is accepted as the standard surgical treatment of cervical spondylotic myelopathy. Cervical disc arthroplasty has gained widespread acceptance as an alternate choice for  ACDF. We intend to present the clinical and radiologic outcomes of patients who underwent ACDF in our department. Methods. Designed as a retrospective study, the primary objective was to assess the nonunion in patients undergoing ACDF and Anterior cervical  Corpectomy and fusion. The article discusses the outcome for the discectomy group. All patients who underwent ACDF for CSM from January 2014 to December 2018 were included. Patients who underwent posterior fusion in addition to anterior approach, revision surgery and congenital anomalies of the spine were excluded. Of the 230 eligible patients,46  subjects were part of the study. They underwent neurologic and radiographic examination and their past records were examined. Neurologic outcome was assessed using Nurick grade and mJOA score. Dysphagia was assessed using the Bazaz score. Neck radiographs were analysed for fusion, Adjacent segment Disease, subsidence, cervical and segmental lordosis. Results. The overall response rate was 25.65%. The mean follows up duration was 4 years. The mean age of the population was 47.1 years. The most common operating level was C5/6. The neurologic status of patients improved from the baseline. There was mild transient dysphagia in 5(10.9%) patients. The overall rate of fusion was 91.3%. Subsidence was seen in 10.9%. Degenerative changes were noted in postop x rays of 67.4% of patients. There was no mortality. Conclusion. ACDF  achieves thorough decompression thereby resulting in neurologic improvement. It produces effective and sustained neurologic improvement. Preoperative adjacent segment degenerative changes were significantly associated with the development of ASD during follow up. This is can due to the progression of the disease. Though the procedure improves the lordosis, it tends to decrease with follow up