Article
Preoperative pathological silent periods correlate with the size of the concomitant syrinx in intramedullary tumors
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Published: | June 8, 2016 |
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Objective: Intramedullary ependymomas are a challenge due to their eloquent location and sometimes invasive growth pattern. Silent periods (SPs) are a method of evaluation of the spinothalamic tract. SP are used in syringomyelia diagnostics. Less is known about the role of SPs in intramedullary tumors. Therefore we analyzed preoperative SPs in our surgical series of cervical intramedullary tumors and investigated possible correlations with symptoms and outcome.
Method: We retrospectively reviewed preoperative electrophysiological parameters of 22 cervical intramedullary tumors that were operated between 2008 and 2014. All patients received a full preoperative electrophysiological work-up, including cutaneous SPs (CSPs), mixed nerve SPs (MNSPs), SEPs and MEPs. Clinical charts were reviewed regarding pain, sensibility, motor function, gait ataxia and reflexes. Tumor diameters and syrinx were measured in preoperative MRI scans.
Results: 22 patients were included in this study. 16 patients had an ependymoma, 2 a cavernoma, 2 an astrocytoma, 1 a hamartoma and 1 a haemangioblastoma. All 16 ependymoma showed a concomitant syrinx. 13 patients showed pathologic CSPs and MNSPs and 10 out of the 14 showed at least 2 pathological SEP or MEP; 3 showed normal preoperative CSPs and MNSPs with no or only insignificant change in SEP or MEP. The length of the syrinx correlated with presence of pathological SPs (p<0.05). All patients with pathological CSPs had a syrinx > 87 mm (mean 183,7 range 87,8 - 275,64 ). The 4 patients with normal CSPs had a syrinx length < 75 mm (mean 48,72 range 29,44 – 74,94 ). Tumor diameters did not correlate with pathological SPs. Neither did presence of pain, dysaesthesia, paresis, gait ataxia and pathological reflexes correlate with pathological SPs. The 7 patients with non-ependymoma intramedullary tumors, all showed pathological CSPs and MNSPs, independently from the size of the tumor and syrinx.
Conclusions: The onset of measurable pathological CSPs and MNSPs in the preoperative evaluation of intramedullary tumors depends on the size of the syrinx and not on the tumor size. Thus SPs do not predict tumor extent or have a predictive value regarding the clinical outcome.