Microvascular decompression for trigeminal neuralgia
Microvascular decompression is a first-line neurosurgical approach for classical trigeminal neuralgia with neurovascular conflict, but can show clinical relapse despite proper decompression. Second-line destructive techniques like radiofrequency thermocoagulation have become reluctantly used due to their potential for irreversible side effects. Subcutaneous peripheral nerve field stimulation (sPNFS) is a minimally invasive neuromodulatory technique which has been shown to be effective for chronic localised pain conditions.
The most frequently used surgical management of trigeminal neuralgia is Microvascular decompression (MVD), followed closely by stereotactic radiosurgery (SRS). Percutaneous stereotactic rhizotomy (PSR) , despite being the most cost-effective, is by far the least utilized treatment modality 1).
Teflon™ and Ivalon® are two materials used in MVD for TN. It is an effective treatment with long-term symptom relief and recurrence rates of 1-5% each year. Ivalon® has been used less than Teflon™ though is associated with similar success rates and similar complication rates 2)
Although microvascular decompression (MVD) is the most effective long-term operative treatment for TN, its use in older patient populations has been debated due to its invasive nature.
Endoscope assisted microvascular decompression for trigeminal neuralgia
Compared with the standard microscope-assisted techniques, the 3D exoscopic endoscope-assisted MVD offers an improved visualisation without compromising the field of view within and outside the surgical field 3).
Fully endoscopic microvascular decompression for trigeminal neuralgia via keyhole approach
97 patients with primary trigeminal neuralgia (PTN) underwent fully endoscopic microvascular decompression (MVD) via keyhole approach in Capital Medical University Affiliated Beijing Shijitan Hospital from December 2014 to February 2019 was collected. During fully endoscopic MVD in PTN via keyhole approach, performer use natural clearance without grinding except developed rock bone crest or excessive retraction of the brain tissue, visually and panoramically observe and evaluate the CPA area, accurately identify the responsible vessels, to avoid the omission of responsible vessels or insufficient decompression. And the use of preplaced technology, bridging technology and submersible technology, ensure the efficacy of surgery and reduce the surgical side injuries. Barrow Neurological Institute Pain Intensity Score was used to evaluate the efficacy and identify the recurrence. The surgical efficacy was analyzed. The offending vessels were identified under endoscope in 96 cases. Among them, arterial compression was found in 77 cases, venous compression in 6 cases, and both arterial and venous compression in 13 cases. About the pain outcomes, 87 cases had immediate and complete relief of pain, 5 cases had almost relief of pain, 4 cases had partial relief of pain, and still needed medication control, but the dose was lower than that before operation, and 1 case had no obvious relief of pain. About complications, there were 4 cases of temporary facial numbness, 1 case of temporary hearing loss, both of them recovered after symptomatic treatment. There was no cerebral infarction or hemorrhage, intracranial or incision infection. All cases were followed up for 3.0-38.0 months with a median period of(22.4±2.2) months. During the follow-up periods, postoperative recurrence occurred in 3 cases. Fully endoscopic MVD for PTN through keyhole approach, provides panoramic view to avoid omission of offending vessels and reduce complications, seemed to be a safe and effective surgical method 4).
Systematic Review and Meta-Analysis
Using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, PubMed, Cochrane Library, and Scopus were queried for primary studies examining pain outcomes after MVD for TN published between 1988 and March 2018. Potential biases were assessed for included studies. Pain freedom (ie, Barrow Neurological Institute score of 1) at last follow-up was the primary outcome measure. Variables associated with pain freedom on preliminary analysis underwent formal meta-analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for possible predictors.
Outcome data were analyzed for 3897 patients from 46 studies (7 prospective, 39 retrospective). Overall, 76.0% of patients achieved pain freedom after MVD with a mean follow-up of 1.7 ± 1.3 (standard deviation) yr. Predictors of pain freedom on meta-analysis using random effects models included (1) disease duration ≤5 yr (OR = 2.06, 95% CI = 1.08-3.95); (2) arterial compression over venous or other (OR = 3.35, 95% CI = 1.91-5.88); (3) superior cerebellar artery involvement (OR = 2.02, 95% CI = 1.02-4.03), and (4) type 1 Burchiel classification (OR = 2.49, 95% CI = 1.32-4.67).
Approximately three-quarters of patients with drug-resistant TN achieve pain freedom after MVD. Shorter disease duration, arterial compression, and type 1 Burchiel classification may predict a more favorable outcome. These results may improve patient selection and provider expectations 5).