Tag: Dorsal column mapping

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Dorsal column mapping in resection of intramedullary spinal cord tumors: a prospective comparison of two methods and neurological follow‑up

Acta Neurochirurgica (2023) 165:3493–3504

In surgery for intramedullary spinal cord tumors (imSCT), distortion of the anatomy challenges the visual identification of dorsal columns (DC) for midline myelotomy. Dorsal column mapping (DCM) and spinal cord stimulation (SCS) can identify DC neurophysiologically. We compare application and feasibility of both methods.

Methods Patients with surgically treated imSCT were prospectively included between 04/2017 and 06/2019. The anatomical midline (AM) was marked. SSEPs at the DC after stimulation of tibial/median nerve with an 8-channel DCM electrode and cortical SSEP phase reversal at C3/C4 after SCS using a bipolar concentric probe were recorded. Procedural and technical aspects were compared. Standardized neurological examinations were performed preoperatively, 1 week postoperatively and after more than 12 months.

Results The DCM electrode detected the midline in 9/13 patients with handling limitations in the remaining patients. SCS was applicable in all patients with determination of the midline in 9/13. If both recordings could be acquired (6/13), concordance was 100%. If baseline SSEPs were poor, both methods were limited. SCS was less time-consuming (p = 0.001), cheaper, and easier to handle. In 92% of cases, the AM and neurophysiologic midlines were concordant. After myelotomy, 3 patients experienced > 50% reduction in amplitude of SSEPs. Despite early postoperative worsening of DC function, longterm follow-up showed significant recovery and improvement in quality of life.

Conclusion DCM and SCS may help confirm and correct the AM for myelotomy in imSCT, leading to a favorable longterm neurological outcome in this cohort. SCS evolved to be superior concerning applicability, cost-effectiveness, and time expenditure.

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Dorsal Column Mapping via Phase Reversal Method: The Refined Technique and Clinical Applications

Dorsal Column Mapping via Phase Reversal Method

Neurosurgery 74:437–446, 2014

Safe resection of intramedullary spinal cord tumors can be challenging, because they often alter the cord anatomy. Identification of neurophysiologically viable dorsal columns (DCs) and of neurophysiologically inert tissue, eg, median raphe (MR), as a safe incision site is crucial for avoiding postoperative neurological deficits. We present our experience with and improvements made to our previously described technique of DC mapping, successfully applied in a series of 12 cases.

OBJECTIVE: To describe a new, safe, and reliable technique for intraoperative DC mapping.

METHODS: The right and left DCs were stimulated by using a bipolar electric stimulator and the triggered somatosensory evoked potentials recorded from the scalp. Phase reversal and amplitude changes of somatosensory evoked potentials were used to neurophysiologically identify the laterality of DCs, the inert MR, as well as other safe incision sites.

RESULTS: The MR location was neurophysiologically confirmed in all patients in whom this structure was first visually identified as well as in those in whom it was not, with 1 exception. DCs were identified in all patients, regardless of whether they could be visually identified. In 3 cases, negative mapping with the use of this method enabled the surgeon to reliably identify additional inert tissue for incision. None of the patients had postoperative worsening of the DC function.

CONCLUSION: Our revised technique is safe and reliable, and it can be easily incorporated into routine intramedullary spinal cord tumor resection. It provides crucial information to the neurosurgeon to prevent postoperative neurological deficits.

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