Seang-Beng Tan

The Torg--Pavlov ratio in cervical spondylotic myelopathy: a comparative study between patients with cervical spondylotic myelopathy and a nonspondylotic, nonmyelopathic population.

Study Design. A radiologic study to compare the Torg–Pavlov ratios between patients with cervical spondylotic myelopathy and a nonspondylotic, nonmyelopathic population. Objectives. To determine and compare the Torg–Pavlov ratios between the two groups of patients. Summary of Background Data. Patients with congenital cervical spinal canal stenosis are more likely to develop cervical spondylotic myelopathy. The Torg–Pavlov ratio eliminates errors related to magnification, a problem with determination of spinal canal stenosis from direct measurements of plain cervical spine radiographs. There has only been one other study that directly compares the Torg–Pavlov ratio between patients with cervical spondylotic myelopathy and a normal control population. Methods. The preoperative plain lateral cervical spine radiographs of 28 patients with cervical spondylotic myelopathy requiring surgical decompression were compared with radiographs of 88 nonspondylotic, nonmyelopathic patients. The Torg–Pavlov ratio was computed for each level from C3 to C7. Results. The study showed that the Torg–Pavlov ratio is significantly smaller (P < 0.001) in myelopathic patients (mean 0.72 ± 0.08) compared with the control patients (mean 0.95 ± 0.14). This was so when individual levels and the mean values were compared. Age was also found to be a significant factor (P = 0.002), although lesser in magnitude when compared with the Torg–Pavlov ratio (P = 0.0001). Conclusions. The Torg–Pavlov ratio is significantly lower in patients with cervical spondylotic myelopathy compared with a nonspondylotic, nonmyelopathic population. It could possibly be used to predict the likelihood of developing cervical spondylotic myelopathy.

Systematic Correlation of Transcranial Magnetic Stimulation and Magnetic Resonance Imaging in Cervical Spondylotic Myelopathy

Study Design. A prospective study over a 3.5-year period involving transcranial magnetic stimulation and magnetic resonance imaging. Objectives. To assess the correlation of transcranial magnetic stimulation and magnetic resonance imaging in cervical spondylotic myelopathy qualitatively and statistically. Summary of Background Data. Cervical spondylotic myelopathy presents with different degrees of cord compression, which can be assessed by magnetic resonance imaging. There are no large studies correlating transcranial magnetic stimulation and magnetic resonance imaging findings in this condition. Methods. A total of 141 patients with a clinical diagnosis of cervical spondylotic myelopathy were prospectively studied over a 3.5-year period. They were classified into Groups 1 to 4 based on severity of cervical cord changes on magnetic resonance imaging. All had transcranial magnetic stimulation and central motor conduction time measurements within 2 months of the magnetic resonance imaging study. Results. Twenty-eight, 49, 28, and 36 patients were classified into Groups 1 to 4, respectively. Mean upper limb and lower limb central motor conduction times correlated with the severity of magnetic resonance cord compression. The absence of central motor conduction time abnormalities correlated reliably with the absence of cervical cord impingement as in Group 1. Statistically significant right left difference in central motor conduction time in the lower limbs was seen between Groups 1 (no cord changes) and Group 2 (mild cord impingement). Eight other patients with diagnoses other than cervical spondylotic myelopathy all showed central motor conduction time abnormalities. The sensitivity and specificity for transcranial magnetic stimulation for differentiating the presence from absence of magnetic resonance imaging cord abnormality were 100% and 84.8%, respectively. Conclusions. Transcranial magnetic stimulation showed excellent correlation with magnetic resonance imaging findings and can be considered as an effective technique for screening patients for cervical cord abnormalities before magnetic resonance imaging in the clinical setting. The findings in this study have relevant implications in the pathophysiology, management, and health costs of cervical spondylotic myelopathy.

Distant skip level discitis and vertebral osteomyelitis after caudal epidural injection: a case report of a rare complication of epidural injections.

Study Design. A case report of distant discitis and vertebral osteomyelitis involving skip levels after caudal epidural steroid injection. Objectives. To report and investigate the occurrence of distant infective discitis and vertebral osteomyelitis involving skip levels after epidural injection. Summary of the Background Data. Distant discitis and vertebral osteomyelitis is a serious but rare complication after epidural injection. A case involving skip levels and without the occurrence of epidural abscess formation has apparently not been previously reported in the literature. Methods. An elderly woman presenting with clinical, radiologic, and magnetic resonance imaging evidence of spinal canal stenosis involving L3/4 and L4/5 levels and degenerative spondylolisthesis of the L4/5 level was given an epidural injection of steroids and lignocaine via the caudal route. A month later, she presented with worsened low back pain, elevated serum acute phase reactants, and plain radiographic evidence of L4/5 infective discitis. Magnetic resonance imaging and microbiologic examination of computed tomographically guided biopsy specimens confirmed infective discitis involving L2/3 and L4/5 intervertebral levels, together with adjacent vertebral osteomyelitis. Results. The patient was successfully treated with antibiotics targeted at Pseudomonas aeruginosa, which was isolated in the culture of the biopsy specimens. Follow-up improvements in the clinical condition, serum acute phase reactants levels, radiographs, and magnetic resonance imaging were noted. Conclusions. Distant discitis and vertebral osteomyelitis involving skip levels and without the occurrence of epidural abscess formation is a serious but rare complication after epidural injection.

Transcranial magnetic stimulation screening for cord compression in cervical spondylosis

OBJECTIVEnCervical spondylosis (CS) often results in various degrees of cord compression, which can be evaluated functionally with transcranial magnetic stimulation (TMS). We investigate the use of TMS as a screening tool for myelopathy in CS.nnnMETHODSnWe prospectively studied 231 patients classified into Groups 1 to 4 based on MRI grading of severity of cord compromise. TMS elicited central motor conduction times and motor evoked potential (MEP) amplitudes in all 4 limbs. The results were compared with those from 45 healthy controls.nnnRESULTSnTMS showed 98% sensitivity and 98% specificity for cord abnormality using MRI as reference standard.nnnCONCLUSIONSnMEP abnormalities are useful for electrophysiological evaluation of cord compression in CS. While TMS is not a substitute for MRI, it is of value as a rapid, inexpensive and non-invasive technique for screening patients before MRI studies.

Two-year outcomes of transforaminal lumbar interbody fusion

Purpose. To evaluate the outcomes, fusion rates, complications, and adjacent segment degeneration associated with transforaminal lumbar interbody fusion (TLIF). Methods. 32 men and 80 women aged 15 to 85 (mean, 57) years underwent 141 fusions (84 one-level, 27 2-level, and one 3-level) and were followed up for 24 to 76 (mean, 33) months. 92% of the patients had degenerative lumbar disease, 15 of whom had had previous lumbar surgery. Radiographic and clinical outcomes were assessed at 2 years. The short-form 36 (SF-36) health survey, visual analogue scale (VAS) for pain, and the modified North American Spine Society (NASS) Low Back Pain Outcome Instrument were used. Results. Of the 141 levels fused, 110 (78%) were fused with remodelling and trabeculae (grade I), and 31 (22%) had intact grafts but were not fully incorporated (grade II). No patient had pseudoarthroses (grade III or IV). For one-level fusions, poorer radiological fusion grades correlated with higher VAS scores for pain (p<0.01). All components of the SF-36, the VAS scores for pain, and the NASS scores improved significantly after TLIF (p<0.01), except for general health in the SF-36 (p=0.59). Improvement from postoperative 6 months to 2 years was not significant, except for physical function (p<0.01) and role function (physical) [p=0.01] in the SF-36. Two years after TLIF, 50% of the patients reported returning to full function, whereas 72% were satisfied. 26 (23%) of the patients had adjacent segment degeneration, but only 4 of them were symptomatic. Conclusion. TLIF is a safe and effective treatment for degenerative lumbar diseases.

Minimally invasive compared with open lumbar laminotomy: no functional benefits at 6 or 24 months after surgery.

BACKGROUND CONTEXTnComparative studies between open and minimally invasive surgical (MIS) approaches for the treatment of spinal stenosis have mainly investigated immediate postoperative parameters.nnnPURPOSEnWe aimed to compare the postoperative improvements in functional and pain scores between open versus MIS lumbar laminotomy and to describe the complications of each method.nnnSTUDY DESIGN/SETTINGnWe conducted as retrospective review of prospectively collected data.nnnPATIENT SAMPLEnWe included 113 patients.nnnOUTCOME MEASURESnVisual analog scale for back and leg pain, Oswestry Disability Index (ODI), the North American Spine Society score on neurogenic symptoms (NS), and average Short Form Health Survey-36 (SF-36) score. Accidental durotomies and patients with reoperations are presented.nnnMETHODSnWe obtained a list of patients who underwent either MIS or open unilateral one-level lumbar laminotomy for the treatment of neural foraminal or lateral recess stenosis with unilateral leg NS. Outcome measures are presented at 6 and 24 months postoperatively.nnnRESULTSnFrom 2000 to 2008, 113 patients (30 open, 83 MIS) underwent a one-level lumbar laminotomy and had complete postoperative data available for analysis. Between the approaches, there were no differences in baseline demographic data or functional scores. At 6 and 24 months after surgery, there were no differences in improvement in back or leg pain, or improvement in ODI, NS, or SF-36 scores. The MIS group reported greater satisfaction with treatment at 6 months (p=.009) but not at 24 months. Within the MIS group, three patients (3.6%) experienced an inadvertent durotomy and two patients (2.4%) underwent fusion of the operated segment within 24 months.nnnCONCLUSIONSnCompared with an open approach, MIS lumbar laminotomy gave no clear advantages in longer term functional or pain scores. The MIS group also had patients with inadvertent durotomies and reoperation within 2 years. In any lumbar decompressive surgery, the purported advantages of an MIS approach should be carefully weighed against potential complications. For a relatively simple surgery such as laminotomy, the open approach remains a safe and straightforward option.

Cutaneous silent periods in the evaluation of cord compression in cervical spondylosis

ObjectiveThe clinical diagnosis of cervical spondylotic myelopathy (CSM) may be challenging in patients with cervical spondylosis (CS). Routine nerve conduction studies (NCS) may not evaluate cord compression adequately.MethodsWe obtained cutaneous silent periods (CSP) in 26 consecutive patients presenting with clinical features of CS, in comparison with 30 normal controls. The results were also compared with transcranial magnetic stimulation (TMS) findings, and magnetic resonance imaging of the cervical cord as the gold standard.ResultsCSP findings showed similarly high sensitivity of up to 96% with TMS in evaluating cervical cord dysfunction.ConclusionIn specific clinical settings, CSP is of value for the diagnosis of CSM in CS. CSP measurement is advocated as a simple and rapid diagnostic adjunct to NCS in evaluating CS patients with possible cord compromise.

The value of bilateral ipsilateral and contralateral motor evoked potential monitoring in scoliosis surgery

Intraoperative monitoring (IOM) of the motor pathways is a routine procedure for ensuring integrity of corticospinal tracts during scoliosis surgery. We have previously demonstrated presence of ipsilateral motor evoked potentials (MEPs) during IOM for scoliosis surgery, but its significance was uncertain. In this case series, we show concurrent ipsilateral and contralateral MEP amplitude changes obtained with cortical stimulation are of value in reducing false positive observations during IOM. The use of this easily recordable MEP is thus advocated as a diagnostic adjunct to contralateral MEPs for scoliosis and spinal surgery.

Intraoperative monitoring study of ipsilateral motor evoked potentials in scoliosis surgery

Ipsilateral motor evoked potentials (MEPs) in spinal cord surgery intraoperative monitoring is not well studied. We show that ipsilateral MEPs have significantly larger amplitudes and were elicited with lower stimulation intensities than contralateral MEPs. The possible underlying mechanisms are discussed based on current knowledge of corticospinal pathways. Ipsilateral MEPs may provide additional information on the integrity of descending motor tracts during spinal surgery monitoring.

Pectoralis major motor evoked potentials in cervical spondylosis

Myelopathy is a severe complication of cervical spondylosis (CS). We studied 27 consecutive patients with CS referred for evaluation for possible myelopathy using transcranial magnetic stimulation. The findings were compared with those from 20 normal controls. Magnetic resonance imaging was utilized to assess the degree of cord compromise. Central motor conduction time (CMCT) abnormalities showed equivalent diagnostic yield with pectoralis major (PM) recordings, as compared with combined first dorsal interossei and abductor hallucis recordings. Our findings show that CMCT measurement with PM recordings is of value as a diagnostic adjunct in the electrophysiological evaluation of myelopathy in CS.