• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.367-375
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• 2019

Hemifacial spasm (HFS) is due to the vascular compression of the facial nerve at its root exit zone (REZ). Microvascular decompression (MVD) of the facial nerve near the REZ is an effective treatment for HFS. In MVD for HFS, intraoperative neurophysiological monitoring (INM) has two purposes. The first purpose is to prevent injury to neural structures such as the vestibulocochlear nerve and facial nerve during MVD surgery, which is possible through INM of brainstem auditory evoked potential and facial nerve electromyography (EMG). The second purpose is the unique feature of MVD for HFS, which is to assess and optimize the effectiveness of the vascular decompression. The purpose is achieved mainly through monitoring of abnormal facial nerve EMG that is called as lateral spread response (LSR) and is also partially possible through Z-L response, facial F-wave, and facial motor evoked potentials. Based on the information regarding INM mentioned above, MVD for HFS can be considered as a more safe and effective treatment.

• Journal of Korean Neurosurgical Society
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• v.52 no.4
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• pp.372-376
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• 2012

Objective : The purpose of this large prospective study is to assess the association between the disappearance of the lateral spread response (LSR) before and after microvascular decompression (MVD) and clinical long term results over two years following hemifacial spasm (HFS) treatment. Methods : Continuous intra-operative monitoring during MVD was performed in 244 consecutive patients with HFS. Patients with persistent LSR after decompression (n=22, 9.0%), without LSR from the start of the surgery (n=4, 1.7%), and with re-operation (n=15, 6.1%) and follow-up loss (n=4, 1.7%) were excluded. For the statistical analysis, patients were categorized into two groups according to the disappearance of their LSR before or after MVD. Results : Intra-operatively, the LSR was checked during facial electromyogram monitoring in 199 (81.5%) of the 244 patients. The mean follow-up duration was $40.9{\pm}6.9$ months (range 25-51 months) in all the patients. Among them, the LSR disappeared after the decompression (Group A) in 128 (64.3%) patients; but in the remaining 71 (35.6%) patients, the LSR disappeared before the decompression (Group B). In the post-operative follow-up visits over more than one year, there were significant differences between the clinical outcomes of the two groups (p<0.05). Conclusion : It was observed that the long-term clinical outcomes of the intra-operative LSR disappearance before and after MVD were correlated. Thus, this factor may be considered a prognostic factor of HFS after MVD.

• Journal of Korean Neurosurgical Society
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• v.49 no.3
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• pp.167-170
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• 2011

Isolated hypoglossal nerve paresis due to mechanical compression from a vascular lesion is very rare. We present a case of a 32-year-old man who presented with spontaneous abrupt-onset dysarthria, swallowing difficulty and left-sided tongue atrophy. Brain computed tomographic angiography and magnetic resonance imaging of the brainstem demonstrated an abnormal course of the left vertebral artery compressing the medulla oblongata at the exit zone of the hypoglossal rootlets that was relieved by microvascular decompression of the offending intracranial vertebral artery. This case supports the hypothesis that hypoglossal nerve palsy can be due to nerve stretching and compression by a pulsating normal vertebral artery. Microvascular decompression of the intracranial nerve and careful evaluation of the imaging studies can resolve unexpected isolated hypoglossal nerve palsy.

• Journal of Korean Neurosurgical Society
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• v.47 no.4
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• pp.271-277
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• 2010

Objective : The purpose of this study is to evaluate the clinical characteristics and surgical outcome of cerebellopontine angle (CPA) epidermoids presenting with trigeminal neuralgia. Methods : Between 1996 and 2004, 10 patients with typical symptoms of trigeminal neuralgia were found to have cerebellopontine angle epidermoids and treated surgically at our hospital. We retrospectively analyzed the clinico-radiological records of the patients. Results : Total resection was done in 6 patients (60%). Surgical removal of tumor and microvascular decompression of the trigeminal nerve were performed simultaneously in one case. One patient died due to postoperative aseptic meningitis. The others showed total relief from pain. During follow-up, no patients experienced recurrence of their trigeminal neuralgia (TN). Conclusion : The clinical features of TN from CPA epidermoids are characterized by symptom onset at a younger age compared to TN from vascular causes. In addition to removal of the tumor, the possibility of vascular compression at the root entry zone of the trigeminal nerve should be kept in mind. If it exists, a microvascular decompression (MVD) should be performed. Recurrence of tumor is rare in both total and subtotal removal cases, but long-term follow-up is required.

• Journal of Korean Neurosurgical Society
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• v.52 no.1
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• pp.42-47
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• 2012

Objective : The aim of this prospective study was to demonstrate the influence of some factors on the prognosis of microvascular decompression in 37 patients with trigeminal neuralgia. Methods : The results of microvascular decompression (MVD) in 37 patients with trigeminal neuralgia were evaluated at 6 months after surgery and were compared with clinical and operative findings. Results : The sex of the patient, the patient's age at surgery, the side of the pain, and the duration of symptoms before surgery did not play any significant roles in prognosis. Also, the visual analogue scale (VAS) of the patient, the duration of each pain attack, and the frequency of pain over 24 hours did not play any significant roles in prognosis. In addition, intraoperative detection of the type of conflicting vessel, the degree of severity of conflict, and the location of the conflict around the circumference of the root did not play any roles in prognosis. The only factors affecting the prognosis in MVD surgery were intraoperative detection of the site of the conflict along the root and neuroradiological compression signs on preoperative magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA). Conclusion : These findings demonstrated that if neurovascular compression is seen on preoperative MRI/MRA and/or compression is found intraoperative at the root entry zone, then the patient will most likely benefit from MVD surgery.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.44-50
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• 2001

Objectives : The objective of this study was to investigate the role of postoperative three dimensional short-range magnetic resonance angiography(3D-TOF MRA) in predicting the clinical outcomes following microvascular decompression(MVD) for the treatment of a hemifacial spasm(HFS). Material and Method : Postoperative magnetic resonance(MR) imaging was performed on 123 patients with a HFS between March 1999 and May 2000. All patients who had postoperative MR imaging were undertaken preoperative MR imaging. Of the 123 patients, 122 patients were included in this retrospective study. The degree of the detachment of vascular contact, and change of the position of offender were determined by pre- and postoperative 3D-TOF MRA. These findings were compared with the surgical findings and clinical outcomes. Results : Of 122 patients who had successful MVD, clear decompression of offenders of the root entry zone(REZ) of facial nerve was found in 106 patients(86.9%), partial decompression in 10 patients(8.2%) and contact of offenders to the REZ of facial nerve in 6 patients(4.9%) by the postoperative 3D-TOF MRA. Our patients demonstrated that the types of offender did not influence with the degree of decompression of REZ of facial nerve and with surgical outcomes(p>0.05). Also, there was no significant relationship between the degree of decompression of the REZ of facial nerve from offenders and an improvement of symptoms(p>0.05). Futhermore, there was no significant relationship between the degree of decompression of the REZ of facial nerve from offenders and an improvement time (p>0.05). Conclusion : Our data suggests that MVD of facial nerve alone may not be sufficient to resolve the symptoms in all patients with hemifacial spasm. Therefore, another unknown factors besides vascular compression may be involved to cause symptoms in certain patients and it may be necessary to remove these factors with MVD simultaneously to obtain the resolution of symptom.

• Journal of Korean Neurosurgical Society
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• v.44 no.6
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• pp.399-400
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• 2008

Hemifacial spasm induced by intracranial aneurysm is a rare clinical condition. A 45-year-old male patient presented with a 3-year history of progressive involuntary twitching movement on right face. On radiological study, a dilated vascular lesion compressing the brain stem was found at the junction of vertebral artery and posterior inferior cerebellar artery. On operative field, we found the posterior inferior cerebellar artery and the fusiform aneurysm compressing root exit zone of facial nerve. Microvascular decompression was performed and the facial symptom was relieved without complications.

• Journal of Korean Neurosurgical Society
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• v.39 no.3
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• pp.183-187
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• 2006

Objective : Hemifacial spasm has characteristic and specific electrophysiological finding, lateral spread response[LSR]. We study the correlation between change of lateral spread response during microvascular decompression[MVD] and clinical outcome after MVD. Methods : Sixty two patients with hemifacial spasm who were treated with microvascular decompression from March 2000 to February 2003 were included in this study. The monitoring of intraoperative facial electromyography[EMG] and brain stem auditory evoked potential were performed. Results : In 28 [44.7%] patients, there was persistence of lateral spread response after vascular decompression in root exit zone of facial nerve. Among these 28 patients, 9 had mild hemifacial spasm at discharge. Three out of 34 patients who had intraoperative disappearance of lateral spread response after MVD had mild hemifacial spasm. But Both groups, disappearance of LSR [Group I], and persistence [Group II] had only 2 patients with mild hemifacial spasm, and 5 patients at 3 months, respectively. Conclusion : Although intraoperative EMG monitoring is very useful in assessing the efficacy of MVD, the clinical outcome of MVD in patient with hemifacial spasm does not always correlate with EMG finding. The prognostic value of intraoperative LSR monitoring in the long-term results is questionable.

• Journal of Korean Neurosurgical Society
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• v.57 no.3
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• pp.221-224
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• 2015

Hemifacial spasm (HFS) is a clinical syndrome characterized by unilateral facial nerve dysfunction. The usual cause involves vascular compression of the seventh cranial nerve, but compression by an artery passing through the facial nerve is very unusual. A 20-year-old man presented with left facial spasm that had persisted for 4 years. Compression of the left facial nerve root exit zone by the anterior inferior cerebellar artery (AICA) was revealed on magnetic resonance angiography. During microvascular decompression surgery, penetration of the distal portion of the facial nerve root exit zone by the AICA was observed. At the penetrating site, the artery was found to have compressed the facial nerve and to be immobilized. The penetrated seventh cranial nerve was longitudinally split about 2 mm. The compressing artery was moved away from the penetrating site and the decompression was secured by inserting Teflon at the operative site. Although the facial spasm disappeared in the immediate postoperative period, the patient continued to show moderate facial weakness. At postoperative 12 months, the facial weakness had improved to a mild degree. Prior to performing microvascular decompression of HFS, surgeons should be aware of a possibility for rare complex anatomy, such as compression by an artery passing through the facial nerve, which cannot be observed by modern imaging techniques.

• Journal of Korean Neurosurgical Society
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• v.65 no.5
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• pp.615-621
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• 2022

Various treatments for trigeminal neuralgia (TN) are known to yield initial satisfactory results; however, the surgical treatment has excellent long-term outcomes and a low recurrence rate. Surgical treatment addresses the challenge of vascular compression, which accounts for 85% of the causes of TN. As for surgical treatment for TN, microvascular decompression (MVD) has become the surgical treatment of choice after Peter J. Jannetta reported the results of MVD surgery in 1996. Since then, many studies have reported a success rate of over 90% for the initial surgical treatment. Most MVDs aim to separate (decompress) the culprit vessel from the trigeminal nerve. To increase the success rate of surgery, accurate indications for MVD and management of the offender vessels without complications are critical. In addition, if there is no vascular compression, partial sensory rhizotomy or internal neurolysis can be performed to improve surgical outcomes.