Microsurgical management of spinal schwannomas: evaluation of 128 cases

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Object

The authors conducted a study to evaluate the clinical characteristics and surgical outcomes in patients with spinal schwannomas and without neurofibromatosis (NF).

Methods

The data obtained in 128 patients who underwent resection of spinal schwannomas were analyzed. All cases with neurofibromas and those with a known diagnosis of NF Type 1 or 2 were excluded. Karnofsky Performance Scale (KPS) scores were used to compare patient outcomes when examining the anatomical location and spinal level of the tumor. The neurological outcome was further assessed using the Medical Research Council (MRC) muscle testing scale.

Results

Altogether, 131 schwannomas were treated in 128 patients (76 males and 52 females; mean age 47.7 years). The peak prevalence is seen between the 3rd and 6th decades. Pain was the most common presenting symptom. Gross-total resection was achieved in 127 (97.0%) of the 131 lesions. The nerve root had to be sacrificed in 34 cases and resulted in minor sensory deficits in 16 patients (12.5%) and slight motor weakness (MRC Grade 3/5) in 3 (2.3%). The KPS scores and MRC grades were significantly higher at the time of last follow-up in all patient groups (p = 0.001 and p = 0.005, respectively).

Conclusions

Spinal schwannomas may occur at any level of the spinal axis and are most commonly intradural. The most frequent clinical presentation is pain. Most spinal schwannomas in non-NF cases can be resected totally without or with minor postoperative deficits. Preoperative autonomic dysfunction does not improve significantly after surgical management.

Abbreviations used in this paper: GTR = gross-total resection; KPS = Karnofsky Performance Scale; MRC = Medical Research Council; NF1 = neurofibromatosis Type 1; NST = nerve sheath tumor; STR = subtotal resection.

Article Information

Address correspondence to: Volker K. H. Sonntag, M.D., Neuroscience Publications, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013. email: neuropub@chw.edu.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    A: Bar graph showing the distribution of sex and age in 128 patients with spinal schwannomas. B: Preoperative axial contrast-enhanced T1-weighted MR image showing an intradural T-8 schwannoma (arrow). C and D: Preoperative and postoperative sagittal contrast-enhanced T1-weighted MR images, respectively, of the same intradural thoracic lesion (arrow).

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    Bar graphs. A: Duration of symptoms for different anatomical locations. There was no statistical difference among these locations (p > 0.05). The 2 intramedullary lesions (asterisk) were not included in the statistical analysis. High variability in the duration of symptoms is reflected in the error bars. B: Duration of symptoms for various tumor levels. There was no statistical difference among these levels (p > 0.05). C: Duration of hospitalization for different tumor locations. There was no statistical difference among different durations of stay (p > 0.05). Although the duration of hospital stay was longer for intramedullary lesions (asterisk), the 2 cases were not included in the statistical analysis. D: Duration of hospital stay for different tumor levels. There was no statistically significant difference among the levels (p > 0.05). Error bars indicate standard deviation.

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    Bar graphs. A: Preoperative and postoperative KPS scores in patients with intradural, extradural, intradural–extradural, and intramedullary spinal schwannomas. Although not significant, the KPS scores at discharge (D/C) were higher than the preoperative KPS scores. At the time of the last follow-up (F/U), however, these scores were significantly higher (asterisk) than the preoperative KPS scores for all tumor locations. B: Preoperative, discharge, and follow-up KPS scores in patients with tumors at various levels. Similar to the different tumor locations in A, the discharge KPS scores were not significantly higher than the preoperative scores. However, the scores were significantly higher at last follow-up for all tumor levels. C and D: Preoperative and postoperative MRC grades of motor strength in patients with spinal schwannomas at various locations (C) and levels (D). Asterisk indicates statistically significant increase (p < 0.05). Error bars indicate standard deviation.

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    Axial MR imaging studies. A: Preoperative T1-weighted contrast-enhanced image of an intradural–extradural C1–2 schwannoma (black arrows). B: Postoperative T1-weighted contrast-enhanced image obtained after surgical management. C and D: Preoperative and postoperative images, respectively, of a large extradural C-7 schwannoma.

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