Neurological outcome after surgical management of adult tethered cord syndrome

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Object

Although postsurgical neurological outcomes in patients with tethered cord syndrome (TCS) are well known, the rate and development of neurological improvement after first-time tethered cord release is incompletely understood. The authors reviewed their institutional experience with the surgical management of adult TCS to assess the time course of symptomatic improvement, and to identify the patient subgroups most likely to experience improvement of motor symptoms.

Methods

The authors retrospectively reviewed 29 consecutive cases of first-time adult tethered cord release. Clinical symptoms of pain and motor and urinary dysfunction were evaluated at 1 and 3 months after surgery, and then every 6 months thereafter. Rates of improvement in pain and motor or urinary dysfunction over time were identified, and presenting factors associated with improvement of motor symptoms were assessed using a multivariate survival analysis (Cox model).

Results

The mean patient age was 38 ± 13 years. The causes of TCS included lipomyelomeningocele in 3 patients (10%), tight filum in 3 (10%), lumbosacral lipoma in 4 (14%), intradural tumor in 3 (10%), previous lumbosacral surgery in 2 (7%), and previous repair of myelomeningocele in 14 (48%). The mean ± SD duration of symptoms before presentation was 5 ± 7 months. Clinical presentation included diffuse pain/parasthesias in both lower extremities in 13 patients (45%), or perineal distribution in 18 (62%), lower extremity weakness in 17 (59%), gait difficulties in 17 (59%), and bladder dysfunction in 14 (48%). Laminectomy was performed in a mean of 2.5 ± 0.7 levels per patient, and 9 patients (30%) received duraplasty. At 18 months postoperatively, 47% of patients had improved urinary symptoms, 69% had improved lower extremity weakness and gait, and 79% had decreased painful dysesthesias. Median time to symptomatic improvement was least for pain (1 month), then motor (2.3 months), and then urinary symptoms (4.3 months; p = 0.04). In patients demonstrating improvement, 96% improved within 6 months of surgery. Only 4% improved beyond 1-year postoperatively. In a multivariate analysis, the authors found that patients who presented with asymmetrical lower extremity weakness (p = 0.0021, hazard ratio 5.7) or lower extremity hyperreflexia (p = 0.037, hazard ratio = 4.1) were most likely to experience improvement in motor symptoms.

Conclusions

In the authors' experience, pain and motor and urinary dysfunction improve postoperatively in the majority of patients. The rate of symptomatic improvement was greatest for pain resolution, followed by motor, and then urinary improvement. Patients who experienced improvement in any symptom had done so by 6 months after tethered cord release. Patients with asymmetrical motor symptoms or lower extremity hyperreflexia at presentation were most likely to experience improvements in motor symptoms. These findings may help guide patient education and surgical decision-making.

Abbreviations used in this paper: EMG = electromyography; HR = hazard ratio; IQR = interquartile range; MMEP = muscle motor evoked potential; MMS = modified McCormick scale; SSEP = somatosensory evoked potential; TCS = tethered cord syndrome.

Article Information

Address correspondence to: Matthew J. McGirt, M.D., 600 North Wolfe Street, Meyer 8-161 Baltimore, Maryland 21287. email: mmcgirt1@jhmi.edu.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    Kaplan-Meier curve depicting the incidence of improvement in motor, sensory, and bladder dysfunction after 29 consecutive cases of first-time adult spinal cord untethering. By 18 months postoperatively, 81% of patients had improved pain, 70% had improved motor weakness, and 50% had improved bladder dysfunction. The rate of improvement was greatest for pain, then motor weakness, then urinary dysfunction (p = 0.040).

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    Kaplan-Meier curves depicting incidence of motor symptom improvement after surgery in patients presenting with either hyperreflexia (A) or mostly unilateral lower extremity weakness (B). Patients presenting with either hyperreflexia (p = 0.037, HR = 4.1) or mostly unilateral lower extremity weakness (p = 0.0021, HR = 5.7) were more likely to experience improvements in motor symptoms.

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    Case 1. Preoperative T2-weighted MR image obtained in a 45-year-old woman with TCS. There was caudal displacement of the conus medllaris to ~ L4–5. The thecal sac extended into a dysraphic defect in the sacral spine.

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    Case 2. Preoperative T2-weighted MR image obtained in a 25-year-old woman who required a second untethering surgery for a symptomatic tethered spinal cord. The medullary conus in this patient extended into the previous surgical defect at ~ L5–S1. The thecal sac was displaced slightly to the right and posterior within a lipoma.

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