Endoscope-assisted neurovascular decompression of the trigeminal nerve: a cadaveric study


Endoscopes are increasingly used to examine cranial nerves in microvascular decompression (MVD) operations. The superior petrosal vein (SPV) is often purposely sacrificed to gain adequate exposure to the trigeminal nerve (TN) during MVD. Recently, the importance of preserving the SPV has been emphasized due to potential complications associated with its sacrifice. Our focus is to study the ability to operate on the TN with preservation of the SPV by using endoscope-assisted microsurgery. We studied both cerebellopontine angles in seven cadaveric heads which vascular system had been injected with colored silicon material. MVD procedures were simulated using the operative microscope (Moeller-Wedel, Cologne, Germany) and two fixed-angled (0°and 30°) rigid endoscopes (Aesculap, PA, USA). To compare the practical advantages of microscopic MVD (MMVD) and endoscope-assisted MVD (EAMVD), we divided the approaches into four subcategories (microscopic without and with SPV sacrifice and endoscope-assisted without and with SPV sacrifice) and compared the maneuverability associated with each category using a numerical grading system. EAMVD scored significantly better than MMVD both without and with cutting of the SPV (p < 0.001). Only in MMVD did cutting of the SPV improve the maneuverability especially in the superior quadrant of the nerve (p = 0.012). Based on the proposed scoring system, use of the endoscope in an assisted mode facilitates visualization and mobilization of the vascular loop associated with the TN without need to sacrifice the SPV. Sacrifice of the SVP may help maneuverability in the superior quadrant of the nerve in MMVD.

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Correspondence to Mario Ammirati.

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Patra Charalampaki, Graz, Austria

The authors described a well designed study about the importance and possibility to protect the superior petrosal vein during trigeminal nerve decompression by using endoscopic assistance in addition to microscopic surgical performance. The study results shows that protection of important structures in the CPA, like SPV, could be possible with the use of an endoscope, because of better visualization and inspection performed with different angled endoscopic tools.

In fact, microscopic vascular decompression for various compression syndromes in the posterior fossa is today a routine procedure performed with very high safety and a low morbidity rate. Therefore, the question may arise whether there is an indication at all for the intraoperative use of endoscopes, and if there is an advantage using them or not? Indeed, most of the microvascular decompressions may be performed without an endoscope-assisted technique. However, the complex syndromes of more than one vessel or cranial nerve involved in the conflict in the same patient may be treated in a safer fashion with the application of intraoperative endoscopy. Studies performed for various compression syndromes in the posterior fossa showed the importance and the high identification rate (almost 100%) of the conflicts with the use of different angled endoscopes for inspecting the pathoanatomic situation in the CPA.

Although we cannot suggest that the outcomes of the endoscope-assisted technique are much superior to the modern microsurgical procedure, there are benefits of reduced morbidity and enhanced efficiency from using endoscopy in cases of vascular decompression. Furthermore, the minimal exploration of the healthy brain without retraction of the cerebellum or manipulation on the neural structures, the circumferential examination of the nerve of interest without manipulation on it, the protection of SPV as one of the important structures in the region, all reduce the complication rates enormously. The endoscope-assisted techniques enable a wide surgical corridor, according to the fisheye like widening of the visual field, as needed to enhance the neurosurgeon's ability to maneuver and simultaneously reduce the injury of normal brain tissue in the surrounding region preserving important structures, like the SPV, as showed in this study.

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A video clip showing a 2-mm diamond burr was applied to drill the suprameatal tubercle under the inspection of a 0° endoscope. After adequate exposure, the root entry zone and further distal portion of the trigeminal nerve were seen. Note: the transpontine vein and AICA loop were explored at the root entry zone just right behind the tubercle. (MPG 22712 kb)


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A video clip showing a 2-mm diamond burr was applied to drill the suprameatal tubercle under the inspection of a 0° endoscope. After adequate exposure, the root entry zone and further distal portion of the trigeminal nerve were seen. Note: the transpontine vein and AICA loop were explored at the root entry zone just right behind the tubercle. (MPG 22712 kb)

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Tang, C., Baidya, N.B. & Ammirati, M. Endoscope-assisted neurovascular decompression of the trigeminal nerve: a cadaveric study. Neurosurg Rev 36, 403–410 (2013) doi:10.1007/s10143-012-0447-5

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  • Cerebellopontine angle
  • Endoscope
  • Microvascular decompression
  • Superior petrosal vein
  • Trigeminal neuralgia