Spatial Distribution Study On Fibers In The Ipsilateral Trigeminal Roots Of Patients With Trigeminal Neuralgia

Part I Electrical stimulation for the ipsilateral trigeminal roots ofpatients with trigeminal neuralgia to observe the spatial distributionof sensory and motor fibersObjectiveTo investigate the spatial distribution of the fibers in the ipsilateral trigeminalroots of patients with idiopathic trigeminal neuralgia, for further direction on theetiology study in idiopathic trigeminal neuralgia and partial sensory rhizotomy.MethodsThe data of30patients with idiopathic trigeminal neuralgia, who underwentmicrovascular decompression (MVD) during September to December in2011, werecollected. Any patient had not underwent a trigeminal destructive operation. All thesurfaces, which were divided into eight zones by using microscope during theoperations, of patients’ ipsilateral trigeminal roots were individually stimulated with0.2mA current. Zone I,II and VIII were considered to belong to the outer flank. zoneIII and VII belong to the middle part. zone IV, V and VI accordingly belong to theinner flank. At the same time of Electrical stimulation, three kinds of compound nerveaction potentials (CNAP),which Respectively belong to the three branches of thetrigeminal sensory nerve, were accordingly recorded at the supraorbital foramen,infraorbital foramen, and mental foramen. On the other hand, explosiveelectromyographic activity called triggered EMG could be recorded in the masseterand temporalis. Finally, the spatial distribution of trigeminal sensory and motor fibersin the trigeminal nerve roots of patients could be determined according to the frequencies of three kinds of CNAPs and triggered EMG.ResultsIn all patients, stable waveforms that signified different responds of differentnerve fibers, were available. Responds were different when stimulating differentzones of nerve root’ surface. Triggered EMG of the masseter and temporalis muscles,as well as CNAPs of different trigeminal sensory branches, were all more likely tooccur at the same time frequently when stimulated zone IV, V or VI of posterior root.while rare responds occurred when stimulated zone I, II or VIII, especially theresponds of triggered EMG as well as CNAP of V1.When stimulated zone III and VII,frequencies of any responds occurrence and the degree of responds mixing turned outto be Medium.Conclusions1. CNAP and triggered EMG can map stably and quickly the Spatial distributionof fibers in the ipsilateral trigeminal roots of patients with trigeminal neuralgia.2. Any kinds of fibers in the ipsilateral trigeminal never root of patients withtrigeminal neuralgia turn out to have a trend of Spatial distribution, rather thankeeping a separate or absolutely fixed position. that is, fibers are more centrally andmixedly distributed in the inner flank, while more rarely or sporadically exist in theouter flank. In the outer flank of almost every posterior root, there existed an partwhich has no conduction function. Motor and first sensory fibers hardly occur in thispart, for they chiefly exist in the inner flank of posterior root.Part II Clinical application of fibers locating under Electricalstimulation in the ipsilateral trigeminal roots of patients withtrigeminal neuralgiaObjectiveTo reduce complication of partial sensory rhizotomy and improve the curative effect.MethodsData of46patients, who were determined to be idiopathic trigeminal neuralgiaduring October,2011to February2012, were collected. It involved38patients that hada relapse or underwent ineffective treatments, including12radiofrequencythermocoagulation，8gamma knife radiosurgery,9peripheral branch avulsion oftrigeminal nerve,2microvascular compression,7patients had received at least2kinds of surgical treatment.;4patients had special conditions, including2with zostervirus infection, one suffered trigeminal neuralgia with hemifacial spasm, and anothersuffered trigeminal neuralgia with glossopharyngeal neuralgia. All the patientsunderwent partial sensory rhizotomy after the location of motor and sensory fibershad been mapped with CNAP and triggered EMG. Postoperative follow-ups, of thecure rate, efficiency, recurrence rate of symptom, as well as the complication, wascompleted.ResultsSpatial distribution trend reflected from CNAP and triggered EMG of fibers intrigeminal root is the same as that found in part1of this dissertation, what is more,the whole frequency of electrophysiological responds in elderly patients turned outhigher than that in younger ones. After amputation, the wound and fibers in the outerflank of trigeminal root, which had been already cut off, reflected none responds. Onthe other hand, none of the strong responds reflected by fibers in the inner flankremained disappeared, while the whole level of their amplitude had declined. Thedegree of amputation in different patients was not the same, according to theelectrophysiological feedback and the different conditions of individuals. Finally, in15cases, less than1/3of the nerve root’s fibers had been cut off, and17cases of1/3~1/2, other14cases of1/2~2/3. After operation,45patients were thoroughly cured,one got a incomplete remission, and one patient had a relapse. The cure rate was97.8%; the efficiency of100%; the recurrence rate within a year was2.2%. NOcerebrospinal fluid leakage or intracranial hemorrhage happened, and none of thepatients suffered keratitis, corneal ulcer or chewing dysfunction.41patients had developed facial anaesthesia,3had dull Corneal reflex.Conclusions1. PSR, which is on the basis of spatial distribution trend reflected from CNAPand triggered EMG of fibers in the ipsilateral trigeminal roots of patients withtrigeminal neuralgia, is practical and feasible.2. Motor and the first sensory fibers, which must not be damaged, are both in theinner flank of the nerve root; while amputation of the fibers in the outer flank turnsout to be safe under intraoperative neurophysiological monitoring,and servercomplication rarely occur.3. PSR under intraoperative neurophysiological monitoring plays an importantrole in the treatment of trigeminal neuralgia, especially when used for curingcomplicated or refractory trigeminal neuralgia, its effect is irreplaceable.