Characteristics and Usefulness of Neurophysiological Monitoring in Corrective Procedures for Abnormally Curved Spine in Young Patients.

PURPOSE: To identify and characterize events of deterioration in intraoperative neuromonitoring data during correction procedures for thoracic and lumbar abnormal spinal curvature in young patients. METHODS: Records of 1,127 cases were retrospectively reviewed to identify events with deterioration of the neuromonitoring data. General etiological and demographic variables were summarized, and neuromonitoring events were studied and characterized. RESULTS: Adolescent idiopathic cases were associated with female dominance and older age. Nonadolescent idiopathic cases were associated with a higher rate of neuromonitoring events. The neuromonitoring events evolved during the different procedural stages, were primarily reflected in the motor-evoked potential data and affected a range of neural structures to varying degrees. Most of the events were resolved, partially or completely, following a corresponding intervention by the surgical team, before the end of the procedure. Significant immediate weakness of the lower extremities was demonstrated in patients with unresolved neuromonitoring events, most of them were nonadolescent idiopathic patients. CONCLUSIONS: Neurophysiological monitoring enables the intraoperative assessment of the integrity of neural pathways and allows the detection of surgery-related impending neural injuries. Neuromonitoring contributes to intraoperative decision making, either when data are uneventful and allow confident continuation or when data deteriorate and lead to corresponding intervention. Further awareness should be paid to the vulnerable characteristics of the patient, surgery course, and neuromonitoring data. Proper interpretation of the neuromonitoring data, together with corresponding intervention by the surgeon when necessary, has the potential to reduce postoperative neurological insults and improve clinical outcomes.

Intraoperative Deterioration of Neurophysiological Potentials of the Spinal Tracts in Cervical Spine Surgery: Correlation With Patient-Related and Procedure-Related Variables.

PURPOSE: To identify characteristics associated with higher incidence of intraoperative deterioration of neurophysiological potentials related to spinal tracts in cervical spine surgeries. METHODS: Electrophysiological raw data and neurophysiological case reports of 1,611 patients from multiple medical centers, who underwent cervical spine surgery for decompression and/or fusion, were retrospectively reviewed. Patient-related and procedure-related variables were identified and analyzed for correlation with intraoperative neurophysiological event of the spinal tracts. The neurophysiological events were analyzed for identification of collective characteristics. RESULTS: The study cohort presented consistent dominancy of male over female patients (67% vs. 33%). Intraoperative deterioration of spinal tract-derived potentials was noted in 10.5% of the total cases, which was not correlated with gender, age, or indication of the surgery. Higher incidence of neurophysiological events was noted in patients with impaired baseline of motor evoked potentials from the thenar muscle ( P = 0.01) or somatosensory evoked potentials of the posterior tibial nerve ( P = 0.0002). Procedures of circumferential approach or procedures that involved ≥3 spinal levels demonstrated higher incidence of neurophysiological events as well ( P = 0.0003 and 0.001, respectively). CONCLUSIONS: Patients with deteriorated neurophysiological baseline and procedures of extensive intervention are at higher risk of intraoperative neurophysiological event in cervical spine surgery. Inclusion of intraoperative neurophysiological monitoring should be encouraged in complicated cases of cervical spine surgeries.

Intraoperative monitoring of corticospinal tracts in anterior cervical decompression and fusion surgery: Excitability differentials of lower extremity muscles.

OBJECTIVE: This study examines and compares excitability characteristics of tibialis anterior (TA) and abductor hallucis (AH) transcranial motor evoked potentials (tcMEP) during anterior cervical decompression and fusion (ACDF) surgery. METHODS: Electrophysiological and clinical data of 89 patients who underwent ACDF procedure were retrospectively reviewed. TcMEP data of TA and AH muscles from 178 limbs were analyzed for availability, robustness and stability during the procedure. RESULTS: TA tcMEP was available at 83% whereas AH tcMEP was available at 99% of the monitored lower limbs at preposition baseline. Availability of both TA and AH tcMEP was demonstrated in 147/178 limbs. The baseline amplitude of AH tcMEP was significantly greater than that of TA tcMEP recorded from the same limb (744.6 ±â€¯54.0 and 326.9 ±â€¯33.3 µV, respectively). Simultaneous deterioration of TA and AH tcMEP data was demonstrated in 10/147 limbs. Deterioration of either TA or AH tcMEP data accompanied by unchanged tcMEP data from the other lower limb muscle was noted in 32/147 compared to 1/147 limbs, respectively. The deteriorated TA and AH tcMEP data returned to baseline before closing at incidence of 17% compared to 46%, respectively. No new lower extremity (LE) neurological deficit was presented postoperatively in any patient. CONCLUSIONS: AH tcMEP is a more reliable candidate than TA tcMEP for intraoperative LE monitoring in ACDF procedure. SIGNIFICANCE: The excitability differentials in LE tcMEP in ACDF is a variable that need to be considered while interpreting intraoperative neurophysiological data.

Multiple cervical levels: increased risk of dysphagia and dysphonia during anterior cervical discectomy.

BACKGROUND: Anterior cervical discectomy (ACD) is widely used for symptomatic cervical spine pathologies. The most common complications associated with this type of surgery are dysphagia and dysphonia; however, the risk factors associated with them have not been adequately elucidated. The purpose of this study is to assess the incidence of self-reported dysphagia and dysphonia and the associated risk factors after ACD. METHODS: This study used a retrospective chart review of 149 patients who underwent ACD at a tertiary care facility operating in the New York metropolitan area over a period of 2½ years. Charts for ACD patients were reviewed by 6 trained researchers. Incidence rates for self-reported dysphagia and dysphonia were calculated using 95% exact confidence intervals (CI). Risk factors such as age, sex, surgical hours, number of disc levels, airway class, American Society of Anesthesiologists class, fiberoptic intubation, and intubation difficulty were assessed using logistic regression. RESULTS: The incidence of self-reported dysphagia was 12.1% (95% exact CI, 7.3%-18.4%); for dysphonia the self-reported incidence was 5.4% (95% exact CI, 2.3%-10.3%). Patients who underwent surgery at ≥4 cervical levels had a significant 4-fold increased risk (odds ratio=4; 95% CI, 1.1-13.8) of developing dysphonia and/or dysphagia compared with patients who underwent surgery at a single surgical level. CONCLUSIONS: This study confirms previous findings that the risk of developing dysphagia and/or dysphonia increases with the number of surgical levels, with multiple cervical levels representing a significantly higher postoperative risk, as compared with surgery at 1 level.

Myokymia in obstetrically related brachial plexopathy.

Myokymic discharges are spontaneous bursts of semirhythmic potentials that are sometimes correlated with rippling movements of skin and muscle. They have been reported in limb muscles in patients with Guillain-Barré syndrome, spinal stenosis, nerve root and nerve compression, and envenomations. They commonly occur with radiation induced plexopathies (approximately 60% of patients), but have not been reported in obstetrically related brachial plexopathies. We report 2 instances of myokymia in children with obstetric brachial plexus palsies. Each child was studied twice, and it was only at the later study, when the child was 10 or 11 months of age, that these potentials were noted. This could represent ongoing recovery from lesions incurred at birth or developmental changes. The final common pathway of all causes of myokymia could be to generate axonal membrane hyperexcitability.