A Series Of Studies On The Treatment Of Trigeminal Neuralgia By Microvascular Decompression

A Series of Studies on the Treatment of Trigeminal Neuralgia by Microvascular DecompressionAs modern microneurosurgery progresses and advances continuously, Microvascular Decompression (MVD) has increasingly been the first choice for the treatment of Trigeminal Neuralgia(TN) in the field of the neurosurgery. Whereas, how to determine the sound indication selection, standardize and regulate treatment method, improve efficacy and lower the occurrence of complications still remain the unsettled issue followed with interests by the clinicians undertaking neurosurgery. Given the topic stated above, we conducted a series of fundamental and clinical studies on the treatment of TN by MVD.Here follow the key points closely concerned with the studies above:①investigation on the anatomical features of the petrous venous and arteries along with its nutrient vessels that enclosing trigeminal nerve root directly pertinent to MVD and the trochlear and abducent nerve involved in MVD potentially.②sound preoperative appraisal and appropriate case selection in the light of the clinical manifestation and its correspondent presentation of the neuroimaging examination.③methodical combination between the observation information on the origin, type, site and severity of neurovascular conflict (NVC) during the operation with the clinical manifestation of TN for better treatment.④adoption of the statistical principle to systemically analyze the key factor that may exerts great influences on treatment efficacy in virtue of the datum gleaning in the follow-up survey for valuable instruction to ameliorate clinical treatment.In sum, it is promised to further regulate the indication for TN treatment by MVD, improve the efficacy of pain relief or even mitigation and avoid the occurrence of post-operative complications by means of the study here focused.Part One:Microanatomic study in the Treatment of Trigeminal Neuralgia by Microvascular DecompressionObjective:To provide micranatomic datum concerned with petrous venous and arterial vessels as well as trochlear and abducent nerve for the treatment of TN by MVD.Material and Methods:We dissected 20 cadaver skulls(40 hemispheres): To begin with, opened the calvaria and removed the entire cerebrum, then opened the tentorium of cerebellum and observed by microscope: (1) the morphology and course of petrous vein as well as its syntopy with trigeminal nerve; (2) the syntopy between the trigeminal nerve and its peripheral blood vessels such as SCA, AICA, BA and so on; (3) the anatomical features on the syntopy between subtentorial trochlear and abducent nerve with trigeminal nerve.Results:(1) In terms of the microsurgical anatomic features such as course and divisions of petrous vein and distance measurement relating to the operation program, we advance the treatment indication and optimal management of the petrous vein during MVD period;(2)There are some blood vessels closely related to trigeminal nerve root including SCA, AICA and pontine branch of basilar artery. And, there are about 87.5% (35/40) of the junction points between SCA trunk and division that are nearest to trigeminal nerve root. Nutrient artery of the Trigeminal nerve root mainly stems from the pontine branch, AICA and SCA of the basilar artery;(3)4.0mm±14.1mm and 6.30mm±1.38mm are the shortest distance measurement between trochlear, abducent nerve and trigeminal nerve respectively.Conclusions:(1) Since petrous venous is contiguous to the trigeminal nerve root, with definite illustration of its anatomical features available, we can manage the petrous venous in a better way so as to initiate a favorable exposure and create a favorable condition for operation;(2) As a coin has two sides, the divisional blood vessels such as SCA, AICA and the pontine branch of basilar artery, while passing by the trigeminal nerve root, may not only compress the nerve root, but also spread its branch to nourish the trigeminal nerve root. It is the shortest span from the trigeminal nerve to the junction point where SCA trunk and its division intersects than any other exhibit;(3) Within the MVD we should attach importance to the anatomical features of trochlear and abducent nerve for better protection.Part Two:Pre-operative Appraisal on the Treatment of Trigeminal Neuralgia byMicrovascular DecompressionObjectives:To explore and argue the indication on the treatment of TN by MVD according to the pre-operative appraisal.Material and Methods:To analyze the clinical manifestation,pain onset, duration, anamnesis and the neuroimaging examination of the 62 patients who once suffered from TN and undergone MVD later and subsequently propose the classification criteria for typical and atypical TN and thereby conduct detailed and comprehensive pre-operative assessment.Results:Of 45 patients with typical trigeminal neuralgia,the mean duration is 3.1 years and the mean age of pain onset is 60.3 years.Single trigeminal division was involved in 20 patients(44.4%),and 2 or 3 divisions were involved in the other 25 patients(55.6%).As for 17 patients with atypical trigeminal neuralgia,the mean duration and the mean age of pain onset is 8.7 years and 55.5 years respectively.2 or 3 trigeminal divisions were involved in all of atypical patients. There is remarkable statistical discrepancy (p＜0.01) between the two groups of patients listed above.Conclusions: (1) the location of trigger point does correspond to the distribution region of the neuralgia;(2) As the duration of TN progresses, we can disclose a trend of transition from typical to atypical TN;(3) MRTA is of unique application in the diagnosis on the etiology of TN.Part Three:Intraoperative observation during the treatment of Trigeminai Neuralgia by Microvascular DecompressionObjectives:Relying on elaborate observation, it is expected to explore and argue each potential affecting factor in MVD treatment efficacy.Material and Methods:Observe and record all detailed datum about the type, site and severity of the neurovascular conflict along with decompression condition carefully in the MVD treatment of 62 patients who once suffered from TN. Neurovascular conflicts(NVC) were classified into five categories: single contact,contact and indentation,single adhesion,adhesion and indentation,and trigeminal nerve atrophy.Results:Of the 62 cases, 47 are classified as arterial vessel compressed by those such as SCA, AICA, PICA, etc; 13 are of arterial and venous simultaneously; 2 are of unidentified. It is the lateral and medial position where neurovascular compression frequently observed.During operation of typical TN, artery compression was found in 39 patients(86.7%),and the combined artery and venous compression was found in 6 patients(13.3%).As for 17 patients with atypical TN,artery compression occurred in 10 patients(58.8%),and the combined artery and venous compression were found in 7 patients(41.2%).Of the all 62 TN, 14 are single contact, 7 are contact and indentation; 15 are adhesion and indentation, 8 are adhesion, indentation and nerve atrophy. Of the 62 cases who underwent MCD, complete decompression were achieved in 50(80.6%)patients while the remaining 12(19.4%) got incomplete decompression.Conclusion:Any microvascualr compression on the intracranial trigeminal nerve root is conducive to lead to onset of TN, therefore,careful exploration should be considered along the root of trigeminal nerve to avoid any offending vessel,especially in the region of medial to trigeminal root and lateral portion of trigeminal root near Meckel's cave. And it is also promised to rationalize, substantiate and validate the operative scheme when MVD responds to the specific compression on the basis of the quanlification and classification of compression degree and severity of NVC.Part Four:Post-operative study on the Treatment of Trigeminal Neuralgia by Microvascular DecompressionObjectives:By means of comprehensive post-operative assay and analysis,we explore the potential influencefactors during operation to regulate the indication of MVD in the treatment of TN. Material and Methods:As for the 62 TN cases underwent MVD, we adopt single and multi-factor statistical analysis to explicate the relationship on the basis of the datum such as gender, age, duration, clinical presentation, intraoperative presentation and treatment efficacy, whereafter, we frame the efficacy appraisal structure scales which far tally with the clinical practice than before:post-operative complete pain relief(excellent),delayed post-operative complete pain relief(better),significant pain relief(good) and no response to MVD(poor).Results:It is remarkably demonstrated that typical TN cases get more notable mitigation treatment than that of the atypical ones, moreover, which are apt to transit into atypical TN especially those with duration of over 3 years, we conduct Logistic multi-factor linear regression analysis for the initial age of pain onset, duration, manifestation and degree of the compression and decompression, which suggest the positive correlation between the five factors mentioned above and the treatment efficacy—positive correlation between clinical manifestation and efficacy (P＜0.05) and significant positive correlation between the remaining four and efficacy (P＜0.01).Conclusions:To better treatment efficacy, it is more appropriate to conduct MVD surgery before the transition from the typical TN developing into atypical TN, which is the most opportune to implement. So, it is far favorable for neurosurgeon to make correct judgment and adjust treatment plan in time so as to improve the overall efficacy when the establishment of the brand-new appraisal system and scales comes into being.