Three-Dimensional Reconstruction of the Distribution of Neurons Contributing to Ophthalmic, Maxillary, and Mandibular Nerves in the Trigeminal Ganglion of Experimental Model

Clinical study of puncture technique in single division of the trigeminal ganglion intumescentia

OBJECTIVE

We explored the feasibility of single-division puncture in the ophthalmic division, maxillary division, and mandibular division of the trigeminal ganglion intumescentia (TGI) and the feasibility of radiofrequency treatment of trigeminal neuralgia.

METHODS

According to the previous anatomical image studies, 3D Slicer software was used to analyze the CT images of the patients. The trigeminal ganglion fossa (TGF) was used as the imaging sign. TGI was identified in the sagittal plane along the fiber. The puncture path starts from the TGI center-foramen ovale line, extending outward to the epidermis as the needle insertion point, and extending inward to the division boundary. For lateral puncture, which is blocked by the mandible, the positions of closed mouth, open mouth, and over-open mouth were used. Multiple targets were generated using straight electrodes and curved electrodes to achieve full coverage of TGI. According to the preoperative design, general anesthesia surgery was performed. Xper CT was used for imaging, and the puncture was guided by Xper Guide. Radiofrequency treatment of TGI was conducted.

RESULTS

In total, 45 patients with trigeminal neuralgia underwent 50 single-division TGI punctures. The procedure was smooth and the compliance with the design was good. Continuous radiofrequency (CRF) was performed, the VAS scores were 25 times at 70°C, 19 times at 65°C, two times at 60°C, and two times at 50°C (both in the ophthalmic division). Pulsed radiofrequency (PRF) was conducted two times. Within 24 h after the procedure, the VAS scores were all 0. From 1 to 7 days after the procedure, pain recurrence was found in three cases, of whom two cases received pulsed radiofrequency treatment. Patients were followed up for 1-24 months and there were no recurrence. After continuous radiofrequency at 65-70°C, the moderate tactile loss was observed, and nearly half of the patients had food residues on the surgical side after 6 months. After continuous radiofrequency at 60°C, there was mild tactile loss and no food residue. The tactile sensation was slightly decreased after continuous radiofrequency at 50°C, and the tactile sensation was normal the next day.

CONCLUSION

Trigeminal ganglion intumescentia single-division radiofrequency is effective and feasible for the treatment of trigeminal neuralgia.

Quantitative assessment of brainstem distortion in vestibular schwannoma and its implication in occurrence of hydrocephalus

PURPOSE

Anatomical distortion directly affects the clinical status of patients with vestibular schwannomas (VSs). It may vary for a given tumor size due to variability in posterior fossa anatomy. We aimed to quantitatively assess brainstem distortion (BSD) and review its role in occurrence of hydrocephalus associated with VSs.

METHODS

Sixty-six patients with small (<3 cm, n= 8; 12.1%); large (3-4 cm; n= 26; 39.4%) and giant (>4 cm; n= 32; 48.5%) VSs were included. Cystic VSs were excluded. Tumor size, tumor-extent, linear displacement (LD; distance between line bisecting pons (line 1) and posterior fossa midline (line 2)) and angular distortion (AD; angle subtended between lines 1 and 2) in axial-T2-MRI section through pons, and their effect on hydrocephalus were assessed.

RESULTS

Significant BSD occurred in a younger age (p value = .004/.003), larger-sized tumor (p value = .001/.002), hydrocephalus (p value = .001/.001), trigeminal (V) nerve palsy (p value = .004/.003) and long tract signs (p value = .001/.034). Tumors crossing midline had significant association with hydrocephalus (p value = .003). LD increased progressively even for 4-5 cm-sized tumors while AD stabilized. Receiver operating characteristic (ROC) curve revealed that diagnostic accuracy of LD (area under the ROC curve (AUROC): 78.9% (95% CI: 67.2%, 90.5%, p < .001)), AD (AUROC:77.6% (95% CI:65.8%, 89.5%, p < .001)) and LD × AD (AUROC:80.3% (95% CI: 69.2%, 91.2%, p < .001)) for predicting occurrence of hydrocephalus was better than tumor size (AUROC: 66.7% (95% CI: 53.5%, 79.9%, p < .05). Cut-off values of LD and AD for predicting occurrence of hydrocephalus were 6.25 mm and 14.6°, respectively. Hydrocephalus was significantly more when both LD was greater than  6.25 mm and AD was greater than 14.5° (p value = .034). The role of LD and AD in influencing hydrocephalus was greater than categorization based on tumor size (Spearman's correlation coefficient: 0.535 and 0.248, respectively). Hydrocephalus occurred at a lesser cut-off value of LD and AD when compared to long tract signs.

CONCLUSIONS

LD and AD values in VSs have a significantly greater influence in the development of hydrocephalus compared to tumor size, and may aid, more reliably, in the prediction of hydrocephalus.

False Localizing Trigeminal V2 Sensory Loss in Vestibular Schwannoma

False localizing signs involving cranial nerves are rare, even more so when involving the trigeminal nerve. Here we present the first case of trigeminal V2 sensory loss as a false localizing sign. The sensory dysfunction was caused by a large contralateral cystic vestibular schwannoma and subsequently improved after tumor resection. The clinical and radiographic features are described, and proposed mechanisms for this false localizing sign are discussed.