Artikel
Surgical resection of intra- and extramedullary tumors by the support of intraoperative ultrasound
Chirurgische Resektion von intra- und extramedullären Tumoren unter Verwendung des intraoperativen Ultraschalls
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Autoren
Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
Magnetic resonance imaging (MRI) is the elementary diagnostic tool in intra- and extramedullary pathologies. Intraoperative ultrasound (IOUS) was used in planning and controlling the operative resection of intradural spinal tumors, in order to define its diagnostic potential and limitations.
Methods
From 1997 to November 2003, 57 patients diagnosed with ependymoma (n=18), astrocytoma (n=6), haemangioblastoma (n=6), neurinoma (n=9), meningeoma (n=10) and filum terminale ependymoma (n=8) were examined using introperative transdural sonography. The sonographic results were correlated to the preoperative MRI-findings and histopathological work-up.
Results
Intramedullary tumors display a heterogeneous image with occasional cystic alterations, an indistinct demarcation as well as an accompanying intramedullary edema. They are therefore easily distinguishable from their extramedullary counterparts which show a homogeneous signal intensity and sharp demarcation. Adequately precise resection control appeared to be possible with all extramedullary tumors; while after the resection of intramedullary tumors a hyperechogenic margin was visible, which does not however enable any reliable statement regarding possible residual tumor tissue. A single hemilaminectomy is sufficient to facilitate the insertion of the scanner. Transdural ultrasound makes it possible to identify the extent of the tumor and its entire cranio-caudal expansion. The surgical approach had to be extended in 8 out of 57 (14%) cases so that the tumor poles could be examined and prepared.
Conclusions
In conclusion, IOUS allows a reliable diagnosis of intraspinal tumors allowing the distinction between intra- and extramedullary tumors through their respective signal characteristics corresponding to the MR-findings. Using IOUS, the extension of the surgical approach can be adopted to the true extent of the tumor, thus avoiding further bone work while the dura is already opened and the frequently edematous spinal cord protrudes through the opening. IOUS has turned out to reduce postoperative morbidity of intradural tumor patients, therefore it should be used as a standard intraoperative tool in these high risk surgical entities.