Identifying Suspected Volume Conduction Contamination of External Anal Sphincter Motor Evoked Potentials in Lumbosacral Spine Surgery.

PURPOSE: Iatrogenic injury to sacral nerve roots poses significant quality of life issues for patients. Motor evoked potential (MEP) monitoring can be used for intraoperative surveillance of these important structures. We hypothesized that volume conducted depolarizations from gluteus maximus (GM) may contaminate external anal sphincter (EAS) MEP results during lumbosacral spine surgery. METHODS: Motor evoked potential from the EAS and medial GM in 40 patients were prospectively assessed for inter-muscle volume conduction during lumbosacral spine surgeries. Peak latency matching between the EAS and GM MEP recordings conditionally identified volume conduction (VC+) or no volume conduction (VC-). Linear regression and power spectral density analysis of EAS and medial GM MEP amplitudes were performed from VC+ and VC- data pairs to confirm intermuscle electrical cross-talk. RESULTS: Motor evoked potential peak latency matching identified putative VC+ in 9 of 40 patients (22.5%). Mean regression coefficients (r2) from peak-to-peak EAS and medial GM MEP amplitude plots were 0.83 ± 0.04 for VC+ and 0.34 ± 0.06 for VC- MEP (P < 0.001). Power spectral density analysis identified the major frequency component in the MEP responses. The mean frequency difference between VC+ EAS and medial GM MEP responses were 0.4 ± 0.2 Hz compared with 3.5 ± 0.6 Hz for VC- MEP (P < 0.001). CONCLUSIONS: Our data support using peak latency matching between EAS and GM MEP to identify spurious MEP results because of intermuscle volume conduction. Neuromonitorists should be aware of this possible cross-muscle conflict to avoid interpretation errors during lumbosacral procedures using EAS MEP.

Chronic subdural haematoma: a case series of uncommon presentations of a common disease.

Chronic subdural haematoma is a common neurological condition especially among the elderly population. Its presentation can be unspecific but often attributed to pressure, cortical irritation, and/or vascular compromise. In the patients' cohort presented below, we have a series of cases where clinical history and examination did not result in an initial clinical diagnosis or suspicion of chronic subdural haematoma, with the diagnosis made only after brain imaging. We reviewed the literature regarding the aetiopathogenesis and clinical features of our patient cohort, which included a young woman with isolated right ptosis and pupillary dilatation, an elderly man with paraplegia, another elderly man with isolated right foot drop, and a young military man with no history of trauma. Our series re-emphasizes the sometimes non-specific and varied clinical presentation of chronic subdural haematoma. We reiterate the need for early brain imaging in patients who present with neurological disorder.

Thoracic spinal extradural arachnoid cyst causing Brown-Sequard-like syndrome: a rare case report and review of literature.

Spinal extradural arachnoid cysts are rare benign lesions occurring along the cerebrospinal axis. They may be associated with pain or varying degrees of neurological compressive symptoms. Brown-Sequard syndrome is a rare sequalae, where there is ipsilateral upper motor neuron paralysis with loss of proprioception as well as contralateral loss of pain and temperature sensation below the lesion. We present a 33-year-old female with a 6-month history of worsening right lower limb weakness and a 2-month history of right lower limb pain. Motor examination revealed right lower limb weakness as well as exaggerated knee and ankle jerk reflexes. A magnetic resonance imaging (MRI) was done, which showed an eccentrically located T4-7 cystic extradural mass causing severe cord compression. She had T4-7 laminectomies with total excision of the cyst and disconnection of the fistulous tract between the cyst and the subarachnoid space. She made full neurologic recovery with no complications.

Temporal analysis of complication rates of cervical spine surgery for degenerative spine disease between younger and older cohorts using the CSORN registry: Is age just a number?

STUDY DESIGN: An ambispective review of consecutive cervical spine surgery patients enrolled in the Canadian Spine Outcomes and Research Network (CSORN) between January 2015 and September 2019. PURPOSE: To compare complication rates of degenerative cervical spine surgery over time between older (> 65) and younger age groups (< 65). More elderly people are having spinal surgery. Few studies have examined the temporal nature of complications of cervical spine surgery by patient age groups. METHODS: Adverse events were collected prospectively using adverse event forms. Binary logistic regression analysis was utilized to assess associations between risk modifiers and adverse events at the intra-, peri-operative and 3 months post-surgery. RESULTS: Of the 761 patients studied (age < 65, n = 581 (76.3%) and 65 + n = 180 (23.7%), the intra-op adverse events were not significantly different; < 65 = 19 (3.3%) vs 65 + = 11 (6.1%), p < 0.087. Peri-operatively, the < 65 group had significantly lower percentage of adverse events (65yrs (11.2%) vs. 65 + = (26.1%), p < 0.001). There were no differences in rates of adverse events at 3 months post-surgery (< 65 = 39 (6.7%) vs. 65 + = 12 (6.7%), p < 0.983). Less blood loss (OR = 0.99, p < 0.010) and shorter length of hospital stay (OR = 0.97, p < 0.025) were associated with not having intra-op adverse events. Peri-operatively, > 1 operated level (OR = 1.77, p < 0.041), shorter length of hospital stay (OR = 0.86, p < 0.001) and being younger than 65 years (OR = 2.11, p < 0.006) were associated with not having adverse events. CONCLUSION: Following degenerative cervical spine surgery, the older and younger age groups had significantly different complication rates at peri-operative time points, and the intra-operative and 3-month post-operative complication rates were similar in the groups.