Fully endoscopic microvascular decompression of the hemifacial spasm: our experience.

PURPOSE: Microvascular decompression (MVD) surgery has been accepted as a potentially curative method for hemifacial spasm (HFS). The primary cause of failure of MVD is incomplete decompression of the offending vessel due to inadequate visualization. This study is aimed at evaluating the benefit of endoscopic visualization and the value of fully endoscopic MVD. METHODS: From March 2016 to March 2018, 45 HFS patients underwent fully endoscopic MVD in our department. From opening the dura to preparing to close, the assistant held the endoscope and the surgeon operated. Abnormal muscle response (AMR) and brainstem auditory evoked potentials (BAEP) were monitored. For every patient, the offending vessel was transposed or interposed and achieved complete decompression. AMR was used to evaluate the adequacy of decompression at the end of the surgery. The intra-operative findings and postoperative outcomes and complications were analyzed. RESULTS: Immediately after surgeries, 39 patients (86.7%) achieved excellent result; 2 cases (4.4%) had good result. So the postoperative effective rate was 91.1% (41/45). During 12-36 month follow-up, the outcomes were excellent in 42 cases (93.3%) and good in 2 cases (4.4%), and the effective rate reached to 97.8% (44/45). No recurrence was noted. The postoperative complications were found in 2 patients (4.4%). One patient (2.2%) showed delayed facial palsy on the tenth day but was fully recovered 1 month later. Intracranial infection was noticed in 1 patient (2.2%) and was cured by using intravenous antibiotics for 2 weeks. There was no hearing impairment, hoarseness, or other complications. CONCLUSIONS: Fully endoscopic MVD is both safe and effective in the treatment of HFS. Electrophysiological monitoring is helpful to gain a good result and reduce hearing impairment.

Posterior Fossa Re-Exploration for Recurrent Trigeminal Neuralgia: Operative Findings and Surgical Techniques.

OBJECTIVE: Microvascular decompression (MVD) is considered the first choice for the surgical treatment of trigeminal neuralgia (TN). However, recurrence after MVD is still a problem and a challenge for neurosurgeons. In this study, we share our experience in the posterior fossa re-exploration of the recurrent cases. METHODS: From January 2014 to January 2015, 15 recurrent TN patients who received fossa re-exploration were retrospectively studied. Surgeries were performed by retrosigmoid suboccipital approach. Brainstem auditory evoked potentials (BAEP) were monitored throughout the operation. Intraoperative findings and surgical techniques were recorded. Postoperative outcomes and complications were analyzed. RESULTS: Among the 15 patients, Teflon adhesion was found in 14. Teflon felt displacement was found in 4 patients, and additional Teflon felt was used to interpose. New offending vessels were found in 5 patients. Three of them were small arteries and the other 2 were petrosal veins. After dissected, small pieces of wet gelatin sponge and Teflon felt were implanted respectively to ensure complete decompression. The remaining 6 patients had no vascular compression except severe adhesion, and nerve combing was performed. After surgery, 12 achieved complete pain relief, 2 gained partial pain relief, and 1 failed. Six patients experienced facial numbness postoperatively. There was no hearing impairment or other complications. During the mean 26-month follow-up, no recurrence occurred and all of 6 cases with facial numbness after surgery improved. CONCLUSIONS: Teflon adhesion is a significant cause of recurrent TN. Wet gelatin-assisted method is good for Teflon interposition. If no vascular compression is found during re-exploration, trigeminal nerve combing can be used. Intraoperative BAEP monitoring is helpful to reduce the incidence of hearing loss.

Management of vessels passing through the facial nerve in the treatment of hemifacial spasm.

BACKGROUND: In hemifacial spasm, it is extremely rare to find a vessel passing through the facial nerve. In this study, we present our experience of the surgical treatment of four such patients. METHODS: From January 2010 to Match 2015, we treated 2,576 hemifacial spasm patients with microvascular decompression in our department. Of these, four had an intraneural vessel. Intraoperative findings and treatment were recorded, and postoperative outcomes were analyzed. RESULTS: In three patients, the intraneural vessel was the anterior inferior cerebellar artery, which we wrapped with small pieces of wet gelatin and Teflon sponge. A small vein found in the fourth patient was treated with facial nerve combing. Complete decompression was achieved and abnormal muscle response disappeared. Three patients got an excellent result and one patient got a good result. One patient had postoperative facial paralysis, which improved over 10 months of follow-up. CONCLUSION: If an artery passes through the facial nerve, it can be decompressed by wrapping the vessel with wet gelatin and Teflon sponge. If a vein passes through the facial nerve, combing can be used. Intraoperative abnormal muscle response monitoring is very helpful in achieving complete decompression.

Microvascular Decompression for Trigeminal Neuralgia: Zone Exploration and Decompression Techniques.

OBJECTIVE: The aim of this study is to introduce zone exploration of the trigeminal nerve and decompression techniques for different types of vasculars. METHODS: The trigeminal nerve was sectioned into 5 zones. Zone 1, 2, 3, 4 was located at the rostral, caudal, ventral, and dorsal part of the nerve root entry zone (REZ) respectively, and zone 5 was located at the distal of the nerve root. This study contained 86 patients with trigeminal neuralgia underwent microvascular decompression. Every zone was exposed through preoperative imaging. During the operation, offending vessels were explored from zone 1 to zone 5, and different decompression techniques were used for different types of vessels. RESULTS: Through zone exploration, the sensitivity of preoperative imaging was 96.5% and specificity was 100%. Location of the neurovascular conflict was in the zone 1 in 53.5% of the patients, zone 2 in 32.6%, zone 3 in 45.3%, zone 4 in 29.1%, and zone 5 in 34.9%. In total, 2 zones were both involved in 59.3%, and 3 zones were involved in 18.6%. All offending arteries were moved away and interposed with Teflon sponge. Offending veins of 11 patients were too small to interpose, and coagulated and cut was adopted. The other offending veins were interposed with wet gelatin and Teflon sponge, respectively. CONCLUSIONS: Zone exploration is helpful in finding offending vessels and adequate decompression can be achieved by choosing different methods according to different types of offending vessels.

Clear cell meningioma: clinical features, CT, and MR imaging findings in 23 patients.

BACKGROUND: Clear cell meningioma (CCM) is a rare meningioma, with radiologic features not well characterized in literature. The purpose of this study was to describe and characterize the clinical features and imaging findings of CCM. MATERIALS AND METHODS: The computed tomography (n = 16) and magnetic resonance (n = 23) images of 23 patients (12 men and 11 women; mean age, 34.6 years) were retrospectively reviewed. All of the patients underwent surgical resection. Follow-up was performed through clinical observations. RESULTS: Cerebellopontine angle was the most frequently presenting location (n = 10). The tumors were isointense (n = 12) or hypointense but associated with isointense (n = 7) appearance to gray matter on T1-weighted images. However, the tumors seemed to be isointense (n = 6) or isointense and hyperintense (n = 13) on T2-weighted images. On gadolinium-enhanced T1-weighted images, heterogeneous enhancement was seen in 14 lesions. Four lesions had amorphous calcifications, 18 showed peritumoral edema, 14 had cystic areas, 2 had bone hyperostosis, and 8 manifested bone destruction. On initial surgery, 17 patients underwent complete resection, whereas 5 patients underwent subtotal resection of their tumors. The operative result for the remaining patient was unknown. Follow-up was possible in 22 patients. Eleven patients had recurrence and 2 had died. CONCLUSIONS: Clear cell meningioma is a rare subtype of meningioma that occurs in younger patients and often recurs. Cerebellopontine angle is the most affected area in this series. The extent of initial surgical resection is the most important prognostic factor. In radiological studies, CCM tends to have marked heterogeneous enhancement, prominent peritumoral edema, intratumoral cystic components, and involvement of the adjacent bone.

Discovery of a new waveform for intraoperative monitoring of hemifacial spasms.

BACKGROUND: Surgeons often rely on intraoperative electrophysiological monitoring to determine whether decompression is sufficient during microvascular decompression surgery for hemifacial spasms. A new monitoring method is needed when an abnormal muscle response is occasionally not available or is unreliable. This study was an observational clinical trial exploring a new waveform recorded from the facial muscles while the offending artery wall was electrically stimulated. METHODS: Thirty-two patients with typical hemifacial spasm and 12 with trigeminal neuralgia as a control were included. The facial muscle response was recorded during microvascular decompression surgery while the offending artery wall was stimulated (2 mA × 0.2 ms). The latency, amplitude, and effective refractory period were analyzed. RESULTS: A waveform was recorded from the facial muscles of patients with hemifacial spasm when the offending artery wall was stimulated and was named the "Z-L response." The latency was 7.3 ± 0.8 ms, the amplitude was 0.08 ± 0.02 mV, and the effective refractory period was 3.5-4 ms. The Z-L response disappeared immediately after microvascular decompression. No waveform was recorded from the facial muscles of patients with trigeminal neuralgia while the anterior inferior cerebellar artery, which adheres to the facial nerve, was stimulated (2 mA × 0.2 ms). CONCLUSION: We found a new waveform for intraoperative monitoring of hemifacial spasm. The Z-L response was useful when the abnormal muscle response was absent before decompression or persisted after all vascular compressions were properly treated. Particularly, the Z-L response may help neurosurgeons determine the real culprit when multiple offending vessels exist.

Surgical treatment of pediatric hemifacial spasm patients.

PURPOSE: To study the clinical features and outcomes of pediatric primary hemifacial spasm patients who underwent microvascular decompression procedures. METHODS: In this retrospective study, five pediatric (<18 years old) primary hemifacial spasm patients underwent microvascular decompression. After surgery, resolution of spasms and surgical complications were observed. Their social adaptability was evaluated using a social adaptation scale, which was designed specially for Chinese middle-school students. RESULTS: Four typical hemifacial spasm patients had immediate excellent or good relief. However, the microvascular decompression procedure did not help the atypical patient much (50% relief of spasm). The score of social adaptation of the pediatric hemifacial spasm patients was 111.6 ± 8.2. Compared with the ordinary healthy Chinese middle-school students, whose score is 170.8 ± 25.4, the patients experienced great difficulty in social adaptation (P < 0.01). After surgery, the scores of two patients increased to a normal level; however, the other three patients remained unchanged. CONCLUSIONS: Microvascular decompression is effective and safe to typical primary hemifacial spasm patients younger than 18 years old. Hemifacial spasm is harmful to the children's social adaptation. However, only some of the patients recovered to the normal social adaptation level even when the spasms were cured.

Study on surgical approaches and electrode implantation of oculomotor nerve and inferior obliquus in beagle dogs.

OBJECTIVES: To study the surgical anatomy and approaches of intracranial oculomotor nerve (OMN) and inferior obliquus (IO), and the methods of their electrode implantation in dogs. METHODS: The research was performed on 30 adult beagle dogs at Shanghai Jiaotong University Medical College, Shanghai, China from November 2007 to August 2008. All animals were subjected to a right transfrontotemperal approach to intracranial OMN, a transconjunctival route to IO, and the neuro-stimulating and recording electrode implantation under general anaesthesia. The OMN was stimulated and the electromyography of IO recorded and analyzed with the Powerlab System. The security and reliability of the implanted electrodes were investigated. RESULTS: The surgical anatomy and approaches of both the OMN from its exit from midbrain to the entrance into cavernous sinus and the IO were described. Moreover, the implantation methods of OMN stimulating electrode and the electromyographic recording electrode of IO were displayed. The implanted electrodes were safe and reliable. Some electrophysiologic data of IO were obtained in the healthy dogs. Also, some perioperative precautions for intracranial and ophthalmic surgical procedures in dog were exhibited. The mortality rate of the dogs was 0%, and no operative complications were observed. CONCLUSION: With the data provided, these surgical approaches and the methods of electrode implantation offer a choice to construct an animal model for studying various aspects of OMN regeneration.

Balloon-Assisted Fistula Sealing Procedure for Symptomatic Tarlov Cysts.

OBJECTIVE: Tarlov cyst is an abnormal expansion of the spinal nerve sleeve, and it communicates with the subarachnoid cavity via a perineural fistula. This study presents our experience of a balloon-assisted fistula sealing procedure in treating Tarlov cyst. METHODS: Twenty-two patients with symptomatic Tarlov cysts were surgically treated. An emulsion balloon was placed into the lumbar subarachnoid cistern through a trocar, so as to temporarily block cerebrospinal fluid flow, then the thecal sac was opened and the inlet of the fistula was sealed by suture of a muscular patch and reinforced by fibrin glue. Finally, the cyst wall was imbricated and the bony cavity was filled with pedicled muscle flaps. RESULTS: Comparing the preoperative and postoperative pain scores according to visual analog scale, 2 patients were slightly improved and 18 patients were substantially improved, including 3 completely pain-free cases. Only 2 patients were unchanged in pain, and both of them had multiple cysts. As a whole, the postoperative pain score was much better than the preoperative score (2.4 vs. 7.5; P < 0.01). Bladder weakness was slightly improved, and bowel dysfunction was almost unchanged after operation. During follow-up, cyst recurrence was found in 1 patient. CONCLUSIONS: The balloon-assisted fistula sealing procedure is safe and effective for Tarlov cyst, especially for the single cyst. It is a good complement to the cyst wall imbricating procedure.

Good Surgical Outcomes of Hemifacial Spasm Patients with Obvious Facial Nerve Indentation and Color Change.

OBJECTIVES: Hemifacial spasm results from vascular compression of the facial nerve. It remains controversial whether severe compression and subsequent nerve indentation predict a good or a poor surgical outcome. Here, to illustrate the relationship between the degree of neurovascular compression and surgical outcome, we conducted a retrospective case-cohort study focused on patients whose facial nerve was seriously compressed. METHODS: This study included 2 groups. The nerve-indentation group included 48 patients with hemifacial spasm whose facial nerves had obvious indentation and color change at the site of neurovascular conflict. The control group included 48 randomly selected patients with hemifacial spasm without facial nerve indentation or color change who were surgically treated by the same team during the same period. The surgical findings, intraoperative lateral spread response results, and clinical outcomes were compared. RESULTS: Single-vessel compression was found more frequently in the nerve-indentation group (87.5%) than in the control group (60.4%, P < 0.05). The lateral spread response (LSR) resolution rate of the nerve-indentation group was 91.7%, and that of the control group was 87.5% (P > 0.05). The rates at which the microvascular decompression procedure was successful were equal in the nerve-indentation and the control groups (93.8% vs. 91.7%, P > 0.05). CONCLUSIONS: Severe vascular compression and subsequent nerve indentation were correlated with a greater possibility of single compression and a lower incidence of multiple neurovascular conflicts in patients with hemifacial spasm, making the microvascular decompression procedure more accurate and easier. Therefore nerve indentation might predict good surgical outcomes.

Management of different kinds of veins during microvascular decompression for trigeminal neuralgia: technique notes.

OBJECTIVE: During microvascular decompression surgery for trigeminal neuralgia, surgeons will encounter various kinds of veins that block the approach to or compress the trigeminal nerve. The aim of this study was to present our experience in managing different kinds of veins. METHODS: This was a retrospective study of 21 patients with trigeminal neuralgia, in whom one or more veins were encountered during surgery. The techniques used in treating 4 types of veins during microvascular decompression were assessed, and the surgical outcomes and operative complications were analysed. RESULTS: For the first type, large veins blocking the approach towards the root entry zone (REZ) of the trigeminal nerve were bypassed via cerebellar fissure approach. Second, veins lying on the brainstem surface and compressing the REZ were detached using a gelatin-assisted dissecting technique and then interposed. Third, veins rising from the surface of the brainstem and crossing the cisternal portion of the trigeminal nerve were interposed. Fourth, intraneural veins, which were generally small, were coagulated and cut. In this series, there was no intentional sacrifice or unintentional rupture of large veins, and the sacrifice rate of medium and small veins was only 19.0%. Thirteen patients (61.9%) gained complete pain relief immediately after surgery (i.e. "excellent" result), while the remaining eight patients (38.1%) achieved "good" pain relief. CONCLUSION: Different surgical techniques were used based on the different kinds of veins encountered. This allowed preservation of almost all the large veins. There were no serious complications postoperatively.

Experimental study on the effect of electrostimulation on neural regeneration after oculomotor nerve injury.

The oculomotor nerve can regenerate anatomically and histologically after injury; however, the degree of functional recovery of extraocular muscles and the pupil sphincter muscle was not satisfactory. Electrostimulation was one potential intervention that was increasingly being studied for use in nerve injury settings. However, the effect of electrostimulation on regeneration of the injured oculomotor nerve was still obscure. In this study, we studied the effects of electrostimulation on neural regeneration in terms of neurofunction, myoelectrophysiology, neuroanatomy, and neurohistology after oculomotor nerve injury and found that electrostimulation on the injured oculomotor nerve enhanced the speed and final level of its functional and electrophysiological recovery, promoted neural regeneration, and enhanced the selectivity and specificity of reinnervation of the regenerated neuron, the conformity among the electrophysiological and functional recovery of extraocular muscles, and neural regeneration, and that the function of extraocular muscles recovered slower than electrophysiology. Thus, we speculated that electrostimulation on the injured oculomotor nerve produced a marked effect on all phases of neural regeneration including neuronal survival, sprout formation, axonal elongation, target reconnection, and synaptogenesis. We think that neural electrostimulation can be used in oculomotor nerve injury.

Oculomotor nerve injury induces nuerogenesis in the oculomotor and Edinger-Westphal nucleus of adult dog.

Technical developments have extensively promoted experimental and clinical studies on cranial nerve regeneration, but intracranial nerve recovery is still an unexplored research area compared to peripheral nerve repair. In this study, we researched whether neurogenesis occurs in adult oculomotor (OMN) and Edinger-Westphal nucleus (EWN) or not after oculomotor nerve injury. To assess cell proliferation in response to unilateral oculomotor nerve crush (ONC) in adult beagle dog, repetitive 5-bromo-2'-deoxyuridine (BrdU) intravenous injections were performed during 3 or 7 days before the dogs were euthanized 2 h after the last injection on days 3, 7, 14, and 28 post-ONC. The proliferating cell types were investigated with three cell phenotypic markers and confocal microscopy on serial sections throughout the whole extent of OMN and EWN. BrdU-positive nuclei were detected in bilateral OMNs and EWNs from 3 to 28 days after ONC with the peak value at 3 days. Confocal analysis revealed that partial BrdU-positive cells colocalized with nestin or ßIII-tubulin or GFAP, and the number of every kind of double-labeled cell maintained an increased tendency from 3 to 28 days post-ONC. Neither single-labeled BrdU-positive nuclei nor double-labeled cells were detected in the subependymal layer of cerebral aqueduct (SELCA) of all unilateral ONC dogs; also, they were not observed in the OMNs, EWNs, and SELCA of intact and sham-operated dog. These findings demonstrate that ONC can trigger continual mitotic activity, proliferation of NSCs, neurogenesis, and astrogliogenesis in the OMN and EWN of adult dogs.

A standardized method to create peripheral nerve injury in dogs using an automatic non-serrated forceps.

This study describes a method that not only generates an automatic and standardized crush injury in the skull base, but also provides investigators with the option to choose from a range of varying pressure levels. We designed an automatic, non-serrated forceps that exerts a varying force of 0 to 100 g and lasts for a defined period of 0 to 60 seconds. This device was then used to generate a crush injury to the right oculomotor nerve of dogs with a force of 10 g for 15 seconds, resulting in a deficit in the pupil-light reflex and ptosis. Further testing of our model with Toluidine-blue staining demonstrated that, at 2 weeks post-surgery disordered oculomotor nerve fibers, axonal loss, and a thinner than normal myelin sheath were visible. Electrophysiological examination showed occasional spontaneous potentials. Together, these data verified that the model for oculomotor nerve injury was successful, and that the forceps we designed can be used to establish standard mechanical injury models of peripheral nerves.

Management of intraneural vessels during microvascular decompression surgery for trigeminal neuralgia.

OBJECTIVE: To present the authors' experience in surgical treatment of patients with trigeminal neuralgia (TN) with intraneural vessels. METHODS: The study included three patients with TN and an intraneural artery (superior cerebellar artery) and eight patients with TN and an intraneural vein. The patients underwent microvascular decompression (MVD) procedures. The intraneural arteries were wrapped by a thin piece of Teflon sponge. The intraneural veins all were coagulated and divided. Clinical outcomes and postoperative complications were analyzed. RESULTS: Eight patients were free of facial pain soon after surgery, achieving excellent outcomes; two patients had good outcomes; and one patient had a failed first operation but experienced pain relief after reoperation, achieving an excellent outcome. Three patients had postoperative facial numbness because the trigeminal nerves were impaired owing to coagulation or mechanical injury. However, no dense corneal numbness or loss of corneal reflex occurred. CONCLUSIONS: If the intraneural vessel is an artery, it can be decompressed by wrapping techniques. Otherwise, intraneural veins should be coagulated and divided. Most patients can achieve excellent or good pain relief with this approach; facial numbness is uncommon.

Hemifacial spasm caused by cross type vascular compression.

OBJECTIVES: The meatal segment of anterior inferior cerebellar artery usually crosses over the gap between cranial nerves VII and VIII, and may compress the cisternal portion (CP) of the facial nerve. This is defined as cross type compression, which is easy to be neglected and thus leads to poor outcome. Here our experience in treating patients of cross type hemifacial spasm (HFS) is reported. METHODS: Twenty-one patients of HFS due to cross type compression were treated with microvascular decompression (MVD) surgery with the aid of abnormal muscle response monitoring. RESULTS: In addition to cross type compression at CP, there were typical vascular compressions on the root exit zone and attached segment in 20 cases. After MVD surgery, 17 patients were cured, 3 patients achieved good resolution of spasm, and the other 1 patient got delayed resolution. Three patients had postoperative transient hearing loss and/or tinnitus. DISCUSSION: Even there are apparently typical vascular compressions at proximal portion of the facial nerve, the surgeon should be aware that cross type compression at the CP may co-exist. With the aid of abnormal muscle response (AMR) monitoring, MVD is efficient for patients due to cross type compression.