Danyluk et al. retrospectively studied trigeminal neuralgia patients undergoing surgical treatment with microvascular decompression. Preoperative magnetic resonance imaging was used for manual tracing of trigeminal nerves and automated segmentation of hippocampus, amygdala, and thalamus. Nerve and subcortical structure volumes were compared between responders and non-responders and assessed for ability to predict postoperative pain outcome.
In all, 359 trigeminal neuralgia patients treated surgically from 2005-2018 were identified. A total of 34 patients met the inclusion criteria (32 with classic and two with idiopathic trigeminal neuralgia). Across all patients, thalamus volume was reduced ipsilateral compared to contralateral to the side of pain. Between responders and non-responders, non-responders exhibited larger contralateral trigeminal nerve volume, and larger ipsilateral and contralateral hippocampus volume. Through receiver-operator characteristic curve analyses, contralateral hippocampus volume correctly classified treatment outcome in 82% of cases (91% sensitive, 78% specific, p = 0.008), and contralateral nerve volume correctly classified 81% of cases (91% sensitive, 75% specific, p < 0.001). Binomial logistic regression analysis showed that contralateral hippocampus and contralateral nerve volumes together classified outcome with 84% accuracy (Nagelkerke R2 = 65.1).
Preoperative hippocampal and trigeminal nerve volume, measured on standard clinical magnetic resonance images, may predict early non-response to surgical treatment for trigeminal neuralgia. Treatment resistance in medically refractory trigeminal neuralgia may depend on the structural features of both the trigeminal nerve and structures involved in limbic components of chronic pain 1).
In a retrospective study, 28 patients older than 65 years (elderly cohort: mean age 70.9 ± 3.6 years) and 38 patients < 65 years (younger cohort: mean age 51.7 ± 6.3 years) underwent MVD via the keyhole retrosigmoid approach for type 1 TN (typical) or type 2a TN (typically chronic) from November 2011 to November 2017. A 75-year-old patient and three nonelderly patients with type 2b TN (atypical) were excluded. Elderly and younger cohorts were compared for outcome and complications.
At a mean follow-up 26.0 ± 5.5 months, 25 patients of the elderly cohort (89.3%) reported a good outcome without the need for any medication for pain versus 34 (89.5%) of the younger cohort. Twenty-three elderly patients with type 1 TN were compared with 30 younger patients with type 1 TN, and no significant difference in outcomes was found (p > 0.05). Five elderly patients with type 2a TN were compared with eight younger patients with type 2a TN, and no significant difference in outcomes was noted (p > 0.05). There was one case of cerebrospinal fluid leak and one of a cerebellar hematoma, both in the younger cohort. Mortality was zero in both cohorts.
In a Single-center, retrospective analysis of patients undergoing RFR for trigeminal neuralgia (TN) from 1995-2016. The primary end-point was subsequent procedure. Associations with rhizotomy parameters and covariates were assessed using Cox regression analysis.
The study included 338 patients, average age 65 years old and 61% female. Temperature was significantly associated with both degree of immediate post-operative pain relief and the duration of pain relief, as well as in subgroup analyses by multiple sclerosis status and RFR procedural count. Ablation duration was also independently significant, though not when analyzed alongside age, sex, and race. Duration of pain relief was generally shorter in patients with multiple sclerosis and in repeat RFR.
Higher temperatures may be necessary to achieve pain relief in some patients given the progressive nature of the facial pain, but are not associated with longer duration of pain relief in patients who have recurrent pain. Modulation of the ablation duration does not seem to affect the short-term or long-term outcomes 3).
97 patients with primary Trigeminal neuralgia (TN) underwent preoperative 3D constructive interference in steady state (CISS) MRI. Image analysis was performed by an independent observer blinded to the operative findings and then compared with surgical data. The 3D reconstruction was assessed dynamically using MIMICS software (Materialise Inc., Leuven, Belgium).
The 3D relationship between visible structures seen on MRI was consistent with the intraoperative findings in all patients. All cases were divided into three groups by the degree of trigeminal nerve encroachment by Superior petrosal vein (SPV). Statistical analysis revealed that the distance from the SPV to the trigeminal nerve was significantly different among the three groups. The diameter of the SPV also differed among the three groups.
Preoperative 3D imaging provides reliable and detailed information about the intraoperative anatomical relationship between the trigeminal nerve and the SPV. This evaluation is useful for preoperative planning 4)
Zheng et al. from Fuzhou retrospectively analyzed forty-four patients with type Ⅰ trigeminal neuralgia who had undergone percutaneous RFT treatment in our hospital from June 2014 to December 2016.The patients were divided into fluoroscopy group and navigation group according to the intraoperative guiding manners for foramen ovale cannulation.We compared groups in terms of the duration of the whole RFT procedure and times of intraoperative fluoroscopy.We also analyzed the immediate and late outcome accessing by Barrow Neurological Institute (BNI) pain scale, as well as the complication rates in groups. Result: There were 32 patients in the fluoroscopy group and 12 in the navigation group.The duration of the surgical procedure in navigation group was less than that in fluoroscopy group (46±12 min versus 67±16 min, P=0.00), and times of intraoperative fluoroscopy was reduced (6.3±2.2 versus 1.3±1.6, P=0.00). The learning curve of navigation-aid RFT was not steep in the present study overall.There was no significant difference between groups regarding pain reduction at the immediate (P=0.07) or late follow-up (P=0.400) time points.However, the rate of pain reduction to BNI-Ⅰ grade was greater in navigation group (P=0.026). No significant difference in the complication rate between both groups, and no serious complications were observed in the both groups. Conclusion: Neuronavigation may be encouraged in trigeminal Gasserian ganglion RFT with better operating efficiency and less radiation exposure.The immediate and late therapeutic effects for craniofacial pain control were positive, whereas further studies are necessary 5).
Surgical and anesthesia records of 27 Trigeminal neuralgia patients who underwent surgical treatment with Internal neurolysis (IN) between March 2010 and September 2016 were retrospectively analyzed. Patients were divided into 2 groups on the basis of the occurrence of trigeminocardiac reflex (TCR) during surgery, and clinical characteristics were compared. Pain intensity was assessed by the Barrow Neurological Institute Pain Scale and Barrow Neurological Facial Numbness Scale.
TCR was observed in 23 of 27 patients (85.2%); it manifested as obvious changes in mean arterial pressure and heart rate by at least 20% of the baseline values. Trigeminal nerve atrophy was found in 9 patients (33.3%). The immediate pain-free rate was 96.3%, and the “excellent” rate was 72.1% for follow-up, with a rate of numbness or hypesthesia of 97.1%. These outcomes were retrospectively compared between the TCR and non-TCR groups, and there was a nonsignificantly higher “excellent” rate in the TCR group than in the non-TCR group.
This study demonstrated that IN is an effective treatment for TN without NVC and has a close relationship with intraoperative TCR. This is the first research describing TCR during IN 6).
Forty-three patients with trigeminal neuralgia were recruited, and diffusion tensor imaging was performed before radiofrequency rhizotomy. By selecting the cisternal segment of the trigeminal nerve manually, they measured the volume of trigeminal nerve, fractional anisotropy, apparent diffusion coefficient, axial diffusivity, and radial diffusivity. The apparent diffusion coefficient and mean value of fractional anisotropy, axial diffusivity, and radial diffusivity were compared between the affected and normal side in the same patient, and were correlated with pre-rhizotomy and post-rhizotomy visual analogue scale pain scores. The results showed the affected side had significantly decreased fractional anisotropy, increased apparent diffusion coefficient and radial diffusivity, and no significant change of axial diffusivity. The volume of the trigeminal nerve on affected side was also significantly smaller. There was a trend of fractional anisotropy reduction and visual analogue scale pain score reduction (P = 0.072). The results suggest that demyelination without axonal injury, and decreased size of the trigeminal nerve, are the microstructural abnormalities of the trigeminal nerve in patients with trigeminal neuralgia caused by neurovascular compression. The application of diffusion tensor imaging in understanding the pathophysiology of trigeminal neuralgia, and predicting the treatment effect has potential and warrants further study 7).
Between January 2003 and December 2013, 360 patients with idiopathic TN and 39 patients with tumor-related TN who had undergone microsurgery were retrospectively studied. Kaplan-Meier survival curves were generated and compared by Log-rank test, and the possible prognostic factors were analyzed by the Cox proportional-hazards regression.
Patients with tumor-related TN exhibited a younger age of pain onset (46.28 ± 18.18y vs. 53.03 ± 11.90y, p = .006), a briefer symptom duration (3.20 ± 4.38y vs. 7.01 ± 6.04y, p = .000), and much more preoperative neuropathic deficits (61.54 vs. 24.17, p = .000), as compared with patients with idiopathic TN. Using Kaplan-Meier analysis, we found microsurgery was effective in 72.3% of patients with idiopathic TN, and in 86.4% of cases with tumor-related TN at six years follow-up postoperatively. Prognostic analysis suggested that a clear-cut neurovascular compression in patients with idiopathic TN (HR = 3.098, 95%CI: 1.800-5.311; p = .000) and total tumor removal in patients with tumor secondary TN (HR = 7.662, 95%CI: 0.098-36.574; p = .044) were positively correlated with excellent long-term outcomes.
The occurrences of TN at younger age, a shorter duration and preponderance of preclinical neuropathic symptoms are the characteristics of TN patients secondary to intracranial tumor, in contrast to patients with TN caused by a compressed vessel. Microsurgery is an effective and safe treatment modality for TN regardless of the disease etiology, the involvement of a clear-cut vascular offender and total tumor resection are the most important predictors of excellent outcome for microsurgery in idiopathic and tumor-related TN patients, respectively 8)