Small Posterior Cranial Fossa and Cerebellopontine Cistern Volumes Are Associated With Bilateral Trigeminal Neuralgia.

Objective: To investigate whether small volumes of the posterior cranial fossa and cerebellopontine cisterns are associated with bilateral trigeminal neuralgia (BTN) and to provide further knowledge regarding the etiology and treatment of this rare disease. Methods: We retrospectively analyzed clinical data and imaging examination results for 30 BTN patients between January 2009 and December 2019. Thirty age- and sex-matched healthy individuals and 30 patients with unilateral trigeminal neuralgia (UTN) were selected as two control groups. The volume of the posterior cranial fossa (VPCF) and volumes of the cerebellopontine cisterns were measured using ITK-SNAP 3.0, which considers the cerebrospinal fluid (CSF) volume based on the region of interest (ROI). Preoperative and postoperative statuses were based on visual analog scale (VAS) pain scores and Barrow Neurological Institute (BNI) scores. Results: A total of 30 patients (11 males; 19 females) were included, and the age of the BTN participants ranged from 41 to 77 (59.93 ± 9.89) years. The duration of TN ranged from 1 to 20 (5.36 ± 3.92) years, and the interval between the two sides ranged from 0 to 3 (1.10 ± 0.79) years. Three patients (10%) in the BTN group had familial trigeminal neuralgia, with no other hereditary history of neurological disorders. In BTN patients, with 25 (83.3%) cases on the left side and 26 (86.7%) on the right side, veins were identified in the operative field and regarded as the individual or offending vessel. The mean VPCF was significantly lower in the patients with BTN than in the healthy controls (4,813 ± 1,155 mm3 vs. 5,127 ± 1,129 mm3, p = 0.008). The volumes of the cerebellopontine cisterns on both sides were significantly smaller in the BTN patients than in the healthy controls (477 ± 115 mm3 vs. 515 ± 112 mm3 on the left side, p = 0.001; and 481 ± 114 mm3 vs. 515 ± 110 mm3 on the right side, p = 0.007). There was no significant difference between the BTN group and the UTN group in terms of the VPCF (4,843 ± 1,184 mm3 vs. 4,813 ± 1,155 mm3, p = 0.402), and there was also no significant difference between the two groups in terms of preoperative VAS pain scores or BNI scores. Conclusion: Overcrowding in the posterior fossa will lead to closer neurovascular relations and, a higher incidence of NVC, and ultimately may be more likely to lead to TN. Veins are the common offending vessels that cause BTN; they might be associated with abnormal vascular development leading to NVC. Microsurgical vascular decompression (MVD) is a safe and effective method for the treatment of BTN, similar to UTN.

Delayed Contralateral Trigeminal Neuralgia After Microvascular Decompression and Postoperative Changes in Venous Outflow.

A 66-year-old woman had presented with a 3-month history of left trigeminal neuralgia. She had undergone successful microvascular decompression for right-sided trigeminal neuralgia 8 years previously. To optimize visualization, microvascular decompression for trigeminal neuralgia has been commonly associated with sacrifice of the superior petrosal vein during surgery. The absence of sufficient collaterals can result in most of the posterior fossa venous drainage relying solely on the contralateral superior petrosal vein, leading to subsequent vessel enlargement and a compressive effect on the trigeminal nerve and causing iatrogenic contralateral trigeminal neuralgia. We have provided preoperative and intraoperative images illustrating nicely the adapted postoperative change in venous outflow causing contralateral compression of the trigeminal nerve. Consecutive treatment effects should be carefully considered when offering and performing surgical microvascular decompression.

Combined Hyperactive Dysfunction Syndrome of the Cranial Nerves: Analysis of 37 Cases and Literature Review.

BACKGROUND: Hyperactive dysfunction syndrome (HDS) of the cranial nerves, such as trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN), is commonly managed by microsurgical treatment. However, certain patients may present a combination of these syndromes in the neurosurgery department. Here, we aimed to retrospectively assess patients with combined HDS from a single center. METHOD: Of 1275 consecutive patients with HDS treated at our center between 2007 and 2017, 37 patients with combined HDS were enrolled, and their medical and surgical records were analyzed. RESULTS: The patients with combined HDS, accounting for 2.9% of all patients with HDS, included 22 patients with bilateral TN, 5 patients with TN-HFS, 8 patients with TN-GPN, and 2 patients with GPN-HFS. A comparison of patients with single and combined HDS indicated a significant difference in the mean age at initial diagnosis (63.57 vs. 56.18 years, P = 0.000) but no such difference in the sex ratio (0.54 vs. 0.59, P = 0.865) or incidence of hypertension (32.43% vs. 24.56%, P = 0.274). In total, 32 microvascular decompression (MVD) procedures were performed in the 27 patients with combined HDS, and repeated MVD was required in 5 patients with bilateral TN. Of the 27 patients who underwent MVD, 25 (92.6%) experienced clinical cure or obvious alleviation. CONCLUSIONS: Combined HDS involves a group of functional disturbance disorders affecting specific cranial nerves, and it may include TN, HFS, and GPN. In addition to gender and incidence of hypertension, age appeared to be a vital indicator for the development of combined HDS, although this finding was inconsistent in previous studies. MVD appears to be a safe and effective treatment for combined HDS, with a high rate of long-term success.