Patients with degenerative cervical myelopathy exhibit neurophysiological improvement upon extension and flexion: a retrospective cohort study with a minimum 1-year follow-up

Abstract

Background Cervical extension and flexion are presumably harmful to patients with degenerative cervical myelopathy (DCM) because they worsen medullary compression visible on dynamic magnetic resonance imaging (MRI). Dynamic somatosensory evoked potentials (SSEPs) are an objective tool to measure the electrophysiological function of the spinal cord at different neck positions. In contrast to previous hypotheses, a considerable proportion of patients with DCM present improved SSEPs upon extension and flexion compared to a neutral position. Methods Patients with DCM who underwent preoperative dynamic SSEP examinations and subsequent decompression surgeries between 2015 and 2019 were retrospectively evaluated. We compared extension and flexion SSEPs with neutral SSEPs in each patient and classified them into extension-improved (EI) or extension-nonimproved (EN) and flexion-improved (FI) or flexion-nonimproved (FN) groups. Preoperative clinical evaluations, decompression surgical methods and one-year follow-up clinical data were recorded. Cervical spondylolisthesis and cervical alignment types were evaluated on plain cervical lateral radiographs. The number of stenotic segments, Mühle stenosis grade and disc degeneration stage of the most severe segment, and presence of ligamentum flavum hypertrophy and intramedullary T2 weighted imaging (T2WI) hyperintensity were evaluated on lateral and axial MRI. Data were compared between the EN and EN groups or FI and FN groups with T-tests, chi-square tests or Kruskal-Wallis tests. Prediction criteria were determined with logistic regression analyses. Results Forty-nine patients were included, and 9 (18.4%) and 11 (22.4%) showed improved extension and flexion SSEPs compared to their own neutral SSEPs, respectively. Interestingly, EI or FI patients had significantly better one-year postoperative mJOA recoveries than EN or FN patients (T-test, P < 0.001). Moreover, the disease duration (T-test, P = 0.024), involved segment number (Kruskal-Wallis test, P < 0.001), and cervical alignment type (chi-square test, P = 0.005) varied significantly between the EI and EN groups. The FI group presented a significantly higher Mühle stenosis grade than the FN group (Kruskal-Wallis test, P = 0.038). Furthermore, ≤ 2 involved segments and straight or sigmoid cervical alignment were significant criteria predicting improved extension SSEPs (probability: 85.7%), while Mühle stenosis Grade 3 and disease duration ≤6 months were significant criteria predicting improved flexion SSEPs (probability: 85.7%). Conclusions Our findings provide evidence for neurophysiological improvement in patients with DCM at extension and flexion and its significance in predicting prognoses. Moreover, certain clinical and radiographic criteria may help predict neurophysiological improvement upon extension or flexion. Trial registration “[2020]151”. Retrospectively registered on April 30, 2020.

Surgical Treatment of Cervical Spondylotic Myelopathy

“…They concluded that cervical motion would worsen the course of CSM, whatever the severity of the patient was. However, a recent retrospective study reported neurological improvement upon extension and flexion in CSM patients [38]. This study reported a significant DSSEP improvement, which is a subjective neurophysiological indicator of the spinal cord, in 18% and 22% of patients during extension and flexion, respectively.…”

Predictive value of dynamic diffusion tensor imaging for surgical outcomes in patients with cervical spondylotic myelopathy

“…The intrinsic mechanism by which dynamic DTI parameters can be evaluated for their postoperative and predictive value may be as follows: in the extension cervical position, the ligamentum avum is anteriorly convex, the spinal canal is narrowed, the longitudinal length and stretch of the cervical cord are reduced, the dorsal subarachnoid space is reduced, and it is susceptible to circumferential pressure; in the exion cervical position, the ligamentum avum is stretched, which increases the longitudinal strain of the spinal cord and results in spinal decompression and improved function, and the dorsal subarachnoid space increases and it is susceptible to anterior pressure. It demonstrated that intramedullary T2WI intensity was maximal compared to the natural neck position and extended neck position [17,18] . Flexion causes anterior and posterior spinal artery compression, decreasing blood supply; extension relieves vascular compression axonal injury within the spinal cord, increases membrane permeability, and leads to loss of conduction in myelinated axons [19] .…”

Developing deep learning-based strategies to predict the risk of hepatocellular carcinoma among patients with nonalcoholic fatty liver disease from electronic health records

“…Patients who were younger than 18 years old on the index date were excluded. To preserve sufficient follow-up and quality of the included data, we followed the inclusion and exclusion criteria used by Kanwal et al [31], and we thus excluded those patients with less than 5 years of data in the Cerner Health FactsÒ database after the index bias introduced by this exclusion criteria will have minimal impact on our method evaluation and is outweighed by the benefit of resulting high quality data as demonstrated by many studies [31][32][33][34]. We excluded patients with hepatitis B or hepatitis C virus to eliminate the impact of these well-known risk factors for HCC.…”

“…Pretrain from scratch Finetune the model pretrained by case-control set date of NAFLD. Since the data is used to evaluate both baseline and deep learning methods, any bias introduced by this exclusion criteria will have minimal impact on our method evaluation and is outweighed by the benefit of resulting high quality data as demonstrated by many studies [31][32][33][34]. We excluded patients with hepatitis B or hepatitis C virus to eliminate the impact of these well-known risk factors for HCC.…”