The Chiari Malformations by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030448622
Publisher: Springer International Publishing

In contrast to our data, Danto et al. reported significant changes in SSEPs, mainly related to positioning, in 32% of 500 patients who underwent surgery for Chiari malformations [59]. Even though these findings could be attributed to the unique characteristics of the patient’s cohort, we did not experience comparable alterations in our series, although a significant number of our patients presented with syringomyelia and preoperative alteration of electrophysiological parameters [3, 52]. This could be attributed to the neurosurgeon’s experience in positioning the patient and the identification of high-risk patients with preoperative electrophysiological recordings, which could guide the surgeon to take special precautions during positioning. However , it should always be considered that there is no reliable relation between the extra- and intraoperative baseline measurements as multiple covariates influence the recordings (e.g., anesthesia, blood pressure, temperature, positioning, electrode impedance). In this respect, only one of the patients who showed electrophysiological changes during positioning in Danto’s series was considered at high risk and underwent preoperative electrophysiological evaluation [59].

As for the SSEP recording, there was a deterioration of the MEP parameters during positioning in 2/33 cases (5%) for which data of continuous monitoring of the upper (H-MEP) and lower extremities (L-MEP) were available in our published series [52]. There were no significant differences in the absolute baseline and final latencies of H-MEPs (p = 0.4126) and L-MEPs (p = 0.2167), as well as the final-to-baseline MEP latency ratio (p = 0.2175). Neither of the two patients who presented a MEP latency increase >10% during surgery developed new postoperative deficits. In contrast, a MEP latency decrease indicated a more favorable outcome, with an improvement in pain symptoms specifically observed during follow-up visits in these patients. Similarly, there was no significant difference of either the absolute baseline and final amplitudes of H-MEPs (p = 0.8427) and L-MEPs (p = 0.7466) or the final-to-baseline MEP amplitude ratios (p = 0.1610). None of the patients who presented a MEP amplitude reduction of >50% during surgery developed new postoperative deficits [52] (Fig. 24.5).

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