Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression

Abstract

Background We investigated the understudied anatomical variations of the superior petrosal vein (SPV) complex (SPVC), which may play some role in dictating the individual complication risk following SPVC injury. Methods Microvascular decompressions of the trigeminal nerve between September 2012 and July 2016. All operations utilized an SPVC preserving technique. Preoperative balanced fast field echo (bFFE) magnetic resonance imaging, or equivalent sequences, and operative videos were studied for individual SPVC anatomical features. Results Applied imaging and operative SPVC anatomy were described for fifty patients (mean age, 67.18 years; female sex and right-sided operations, 58% each). An SPVC component was sacrificed intentionally in 6 and unintentionally in only 7 cases. Twenty-nine different individual variations were observed; 80% of SPVCs had either 2 SPVs with 3 or 1 SPV with 2, 3, or 4 direct tributaries. Most SPVCs had 1 SPV (64%) and 2 SPVs (32%). The SPV drainage point into the superior petrosal sinus was predominantly between the internal auditory meatus and Meckel cave (85.7% of cases). The vein of the cerebellopontine fissure was the most frequent direct tributary (86%), followed by the pontotrigeminal vein in 80% of SPVCs. Petrosal-galenic anastomosis was detected in at least 38% of cases. At least 1 SPV in 54% of the cases and at least 1 direct tributary in 90% disturbed the operative field. The tributaries were more commonly sacrificed. Conclusions The extensive anatomical variation of SPVC is depicted. Most SPVCs fall into 4 common general configurations and can usually be preserved. BFFE or equivalent sequences remarkably facilitated the intraoperative understanding of the individual SPVC in most cases.

Vein-related Trigeminal Neuralgia: How to Determine the Treatment Method of the Causative Vein: A Technical Note

“…Hence, the contact patterns of bridging veins and their tributaries can be infinite in both number and direction. 1,7,11,12) Matsushima et al classified veins around the trigeminal nerve into the following four groups: group 1: anterior pontomesencephalic draining; group 2: posterior mesencephalic draining; group 3: tentorial cerebellar surface draining; and group 4: petrosal fissure draining. 11) Preoperative imaging should be used to assess the group to which the causative vein belongs, and treatment should be decided after identifying its perfusion range and collateral venous outflow.…”

Deadly complication of sacrificing superior petrosal vein during cerebellopontine angle tumor resection: A case report and literature review

“…group updated the classification as Type1, Type 2, and Type 3 based on relationship of its site of entry into the SPS, Meckel cave, and the internal acoustic meatus (IAM) [ Figure 4 ]. [ 4 , 20 , 27 ] In Type 1, the SPV complex empties in to the superior petrosal sinus (SPS) or lateral to the IAM. In Type 2, SPV complex empties into the SPS between the lateral limit of the trigeminal nerve and the medial limit of facial nerve.…”

“…SPS: Superior petrosal sinus, SPV: Superior petrosal vein, V: Fifth cranial nerve, VII/VIII: Seventh and eight cranial nerves. [ 4 ]…”

“…ALMv: Anterior lateral marginal vein, PTv: Pontotrigeminal vein, SPS: Superior petrosal sinus, SPV: Superior petrosal vein, SPVC: Superior petrosal vein complex, SPV1: First superior petrosal vein, SPV2: Second superior petrosal vein, SPV3: Third superior petrosal vein, TPv: Transverse pontine vein, v.CPF: Vein of cerebellopontine fissure, v.MCP: Vein of the middle cerebellar peduncle, V: Trigeminal nerve, VII/ VIII: Seventh and eighth cranial nerves. [ 4 ]…”

“…[ 16 ] Injury of a part of the SPVC has been frequently reported in large case series, with an incidence ranging from 55% to 84% of cases. [ 4 ]…”