Technical Considerations to Prevent Postoperative Endocrine Dysfunction after the Fenestration of Suprasellar Arachnoid Cyst

OBJECTIVE: The endocrine dysfunction after the operation for suprasellar arachnoid cysts is not rare. The careful operation to prevent structures can prevent this complication, but it is not enough and effective to prevent it. Authors present technical surgical considerations to prevent this complication with a review of our suprasellar arachnoid cyst patients who had postoperative endocrine dysfunction. METHODS: From January 2002 to December 2009, eight patients who had suprasellar arachnoid cysts with visual impairment underwent surgery. The mean age was 57.1 years (range, 33-77). Preoperatively, their endocrine function was clinically normal, and laboratory hormonal levels were within normal ranges. Cyst fenestration was performed by craniotomy (n=6) or by a neuro-endoscopic procedure (n=2), and, simultaneously, along with a cyst wall biopsy. RESULTS: The surgery was uneventful in all eight patients, and there were no neurological morbidities. However, in four patients, endocrine dysfunction occurred postoperatively. We compared these four patients (group A) to the other 4 patients without endocrine dysfunction (group B) with intraoperative findings and with the histopathological findings of the cyst wall biopsy. The group A patients had more abundant vasculature on the cystic wall than the group B patients according to both the intraoperative findings and the histopathological findings. CONCLUSION: When performing a surgical cyst wall fenestration, surgeons should try to minimize the destruction of the cystic wall vasculature and not to make the fenestration at a site that contains many vascular striae.

Tailored Surgical Approaches for Benign Craniovertebral Junction Tumors

OBJECTIVE: We report our surgical experience in the treatment of 16 consecutive patients with benign craniovertebral junction (CVJ) tumor, observed from 2003 to 2008 at our department. METHODS: We had treated 6 foramen magnum meningiomas, 6 cervicomedullary hemangioblastomas, 1 accessory nerve schwannoma, 1 hypoglossal nerve schwannoma, 1 C2 root schwannoma, and 1 cavernous hemangioma. Clinical results were evaluated by Karnofsky Performance Scale (KPS) and all patients underwent preoperative neuroradiological evaluation with computed tomography (CT) and magnetic resonance image (MRI). Angiography was performed in 15 patients and preoperative embolization was done in 2 patients. RESULTS: Five far-lateral, 1 supracondylar and 10 midline suboccipital approaches were performed. Gross total removal was achieved in 15 cases (94%) and subtotal removal in 1 patient (6%). None of the patients required occipitocervical fusion. Radiological follow-up showed no recurrence in cases totally removed. Postoperative decrease of KPS scores was recorded in only 1 patient. The treatment of cervicomedullary solid hemangioblastoma presented particular issues : by preoperative embolization, we removed tumor totally without an excessive bleeding or brainstem injury. In one of foramen magnum meningioma, we carried out subtotal removal due to hard tumor consistency and encasement of neurovascular structures. CONCLUSION: : The choice of surgical approaches and the extent of bone resection should be defined according to the location and size of individual tumors. Moreover, we emphasize that preoperative neuroradiological evaluations on presumptive tumor type could be helpful to the surgeon in tailoring the technique and providing the required exposure for different lesions, without unnecessary surgical steps.

Juvenile Pilomyxoid Astrocytoma in the Opticohypothalamus

Pilomyxoid astrocytoma (PMA) is a newly recognized variant of a pilocytic astrocytoma. This report describes a case of a pilomyxoid astrocytoma that occurred in the opticohypothalamus. The patient was a 18-year-old girl who complained decreased visual acuity and visual field over a period of two years. Magnetic resonance imaging (MRI) showed an irregular lobulated tumor with heterogeneous enhancement at the suprasellar region involving the hypothalamus. The mass was partially removed via the subfrontal approach. Its pathology was confirmed to be PMA. Adjuvant chemotherapy with cisplatin and vincristine was started following tumor resection. After four cycles, the mass showed a partial response to the chemotherapy. Although long-term outcome is yet to be determined, the administration of combined cisplatin and vincristine treatment seems to be an effective regimen for a pilomyxoid astrocytoma.

Correlation of Clinical and Immunohistochemical Diagnosis in Patients with Pituitary Adenomas

OBJECTIVES: Pituitary adenomas are common neurological lesions believed to account for 10% to 15% of all primary brain tumors. There can be diagnostic confusion due to discordance of the preoperative endocrine and the postoperative immunohistochemical diagnosis. In this study, the rate of discordance between preoperative and postoperative findings and their clinical implications were investigated. METHODS: From March 2005 to March 2006, 26 patients who underwent surgery for a pituitary adenoma were enrolled in this study. The preoperative pituitary hormone level and postoperative immunohistochemical results were compared and analyzed. RESULTS: The median age of the patients was 38 years (range 15-66 years). The male to female ratio was 8 to 18. The endocrine evaluation showed 16 hormonally-active and 10 hormonally-inactive adenomas. The immunohistochemical findings showed : 13 prolactin-positive, 1 GH-positive, 1 FSH-positive, 8 pleurihormone-positive and 3 stain-negative adenomas. The percentage of discordance observed between the preoperative endocrine and postoperative immunohistochemical diagnosis was 54%. Nine of 10 endocrine non-functioning adenomas showed : 3 PRL positive, 1 GH positive, 2 PRL+GH positive, 1 TSH+FSH positive, 1 FSH+ACTH+PRL positive and 1 FSH+LH+PRL positive adenomas by immunohistochemistry. Three endocrine PRL+GH secreting adenomas showed 2 PRL positive and 1 FSH+GH positive by immunohistochemistry. One endocrine PRL secreting and 1 GH secreting adenoma showed 1 PRL+TSH positive and 1 GH+PRL positive by immunohistochemistry, respectively. The diagnosis of the other 12 pituitary adenomas showed concordance. CONCLUSION: The results of this study showed 54% discordance rate between the preoperative endocrine and postoperative immunohistochemical diagnosis for pituitary adenomas.

Visual Outcome after Surgical Removal of Craniopharyngiomas

OBJECTIVE: In the present study, we evaluate visual outcomes after surgical removal of craniopharyngiomas and analyze the factors that are considered to affect visual outcomes. METHODS: This study includes 30 patients with craniopharyngioma, who underwent surgery in this clinic during the last 10 years. The changes of visual function (visual acuity and field) of the patients were assessed preoperatively and postoperatively, and paired data of this change were compared. Also, the factors that influence on this change were analysed. RESULTS: Among the 21 patients complaining of decreased vision before the operation, 8 patients were improved (38.0%), and 7 patients were worse (33.3%). However, Four out of 9 patients without any preoperative visual symptoms developed worse vision after the operation (44.4%). The average duration of symptom was 17.2 months in the improved group and 23.6 months in the aggravated group. The tumors recurred in only 5 patients after the gross total resection: Four of them showed the aggravation of visual function after surgical removal and 1 had improvement. CONCLUSION: After removal of craniopharyngiomas, the overall rate of vision improvement, no change and aggravation are 26.6%, 36.7% and 36.7%, respectively. Aggravation of postoperative visual function is higher in males, children and patients with a longer duration of symptom and the tumor recurres more frequently in patients who complained of worsened vision after surgical removal.

Surgery of a Solid Hemangioblastoma at the Cervicomedullary Junction

The surgical removal of solid deepseated hemangioblastomas remains challenging, because treatment of these lesions is often complicated by severe bleeding associated with the rich vascularity of this tumor, and by severe neural tissue injury associated with the difficulty of en bloc resection, especially when the tumor is located at the cervicomedullary junction. Therefore, preoperative embolization of deepseated solid hemangioblastomas may play an important role in successful surgical removal by reducing major bleeding and neural tissue damage. A 24-year-old woman, 28-weeks pregnant, was admitted to our hospital for the evaluation of quadriparesis, and brain magnetic resonance imaging(MRI) revealed intra-axial mass lesion in the cervicomedullary junction. After delivery, her neurologic symptoms became aggravated, and we decided to operate. Preoperative angiography revealed a hypervascular tumor in the posterior fossa, and embolization of the main feeding artery using gelfoam and microcoil, resulted in marked reduction of tumor vascularity. She underwent a midline suboccipital craniotomy involving the removal of the arch of C-1. The tumor was totally removed through a midline myelotomy, and at her 6-month follow-up she walked independently. We report on the combined use of the preoperative embolization of feeding vessels and subsequent operative resection in a patient with a solid hemangioblastoma at the cervicomedullary junction immediately after delivery.

Acute Hearing Loss in the Contralateral Ear after Vestibular Schwannoma Removal

Hearing loss in the contralateral functioning ear is a rare and distressing complication after vetibular schwannoma removal. Various possible mechanisms have been proposed, however, the etiology of hearing loss is not clear. Fortunately, this is an extremely rare occurrence, sporadic case reports have appeared in the literatures. We report two cases of acute contralateral hearing loss after vestibular schwannoma removal and discuss the possible mechanisms of the phenomenon. Although permanent deafness may result, in our cases, the hearing loss was temporary, returning to near preoperative level within one month. The etiology of hearing loss in one case is thought to be cerebrospinal fluid leakage. However, in the other case, the cause of hearing loss is not clear. A better understanding of these events may lead to preventive measures to avoid contralateral hearing loss after vestibular schwannoma removal.

Clip Reinforcement Technique by Circumferential Wrapping with Silastic Sheet for Treatment of Cerebral Aneurysms and Its Follow-Up Outcome / 대한뇌혈관외과학회지

OBJECTIVE: To describe the clip reinforcement technique by circumferential wrapping with silastic sheet for the treatment of unclippable cerebral aneurysms and evaluate its long term follow-up results. METHODS: The nature of 26 unclippable aneurysms were as follow:12 blister-like superior wall aneurysm of internal carotid artery (ICA), 6 microaneurysms (<2 mm), 4 fusiform aneurysms, 4 broad-based aneurysms. After aneurysm and the parent artery are circumferentially wrapped by silastic sheet, aneurysm clips are positioned on the sheet with parallel to the parent artery. The mean follow-up period was 37 months (range, 3-140 months). RESULTS: 25 of 26 patients had a favorable outcome and one patient had a severe disabled due to severe vasospasm at 3 months after operation. Of the 21 patients who underwent immediate angiographic examination, stenosis of parent artery was detected in 6 patients and remnant of aneurysm in 4 patients. Asymptomatic occlusion of parent artery was observed in one patient on follow-up angiographic examination. 22 of 24 patients followed-up for a long time had a favorable outcome and 2 patients had a severe disabled (one patient was due to previous severe disabled and the other was due to thalamic intracerebral hematoma developed during the follow-up period). CONCLUSION: In our study, there was no clip reinforcement technique-related clinical complications such as rebleeding of aneurysm or ischemic event during follow-up period. Clip reinforcement technique by circumferential wrapping with silastic sheet is simple and useful method for the unclippable cerebral aneurysm.

Parasagittal Meningiomas: Surgery & Postoperative Complications

OBJECTIVE: The authors report the evaluation of the surgical outcomes and postoperative complications for the 39 cases of parasagittal meningioma. METHODS: Thirty-nine patients have undergone operations for parasagittal meningioma between March 1994 and March 2002. The medical records and neuroimaging studies of thirty-nine patients were surveyed retrospectively to find out the perioperative clinical status, radiologic findings, operative methods, and postoperative complications. RESULTS: Preoperative symptoms were motor weakness(12), seizure(11), headache(11) and so on. The parasagittal meningioma was classified into lateral attachment(27), partial occlusion(4) or total occlusion(8) according to the degree of infiltration and into anterior one third(7), middle one third(28) or posterior one third(4) from the viewpoint of the origin site. The degree of tumor removal was classified into Simpson Grade: Grade I(13), Grade II(24), Grade III(2). Suture of the opened sinus was done in seven patients going through an operations. Four patients of them underwent sinus opening for mass removal and the others due to operative injury. Total removal of the sinus segment was carried out in six patients. The draining veins of six patients got injuried, those of four patients and the others respectively were coagulated and sutured. Postoperative complications were motor weakness(11), CSF leakage(9), seizure(1) and hemorrhage(1). CONCLUSION: However, most of the weakness is transient, the preservation of intracranial collateral circulation is important to minimize the motor weakness. The effort for complete tumor removal is required in parasagittal meningioma to take recurrence into account.

The Clinical Experience of Neuronavigation System in Brain Tumor Surgery

OBJECTIVE: Neurosurgical technique has recently entered a fantastic era of image guided surgery or neuronavigaton and application of this technology is beginning to have a significant impact on a variety of intracranial procedures. This study purports to investigate the effectiveness of this new technique in its application to the brain tumor surgery. METHODS: We used the BrainLab VectorVision neuronavigation system, which is an intraoperative, imageguided, frameless, and localization system. We operated 220 cases of different brain pathological conditions with its guidance. RESULTS: The mean of target localizing accuracy, mass size, and mass volume were 1.14mm, 3.04x3.78cm, 32.04cc respectively. These cases included 194 microsurgical craniotomies, 21 frameless stereotactic biopsies, 4 endoscopic procedure and 1 catheter placement. The common pathological diagnoses were meningioma in 61 cases, glioma in 59 and metastasis in 45. CONCLUSION: The neuronavigation system has shown to be very effective and user-friendly for routine microsurgical interventions. The application of this technique not only revealed benefits in operative planning, appreciation of anatomy, lesion location, and safety of surgery, but also greatly enhanced surgical confidence. The image guided surgical technology has a great potential to play an important role in contemporary neurosurgery and its various adoptions in practice will be realized in the near future.

Functional MR Imaging Using BOLD Technique in Patients with Brain Tumors

PURPOSE: To reveal clinical usefulness of functional MRI (fMRI) using sensorymotor and language stimuli for demonstrating anatomic relationship between sensorimotor or language cortices and lesions in the planning of brain tumor surgery. MATERIALS AND METHODS: This study included 12 right-handed patients with brain tumors in or around sensorimotor or language cortices. Eleven patients were evaluated with primary motor and sensory stimuli. Of these patients, six patients were also evaluated with language stimuli. One patient was evaluated with language stimuli only. For fMR imaging, a 1.5T scanner was used and the EPI BOLD technique was employed. For postprocessing image, the SPM99 program and a program made by our department was utilized. We evaluated whether sensorimotor and language stimuli activate sensorimotor and language cortices. And also, clinical efficacy of revealing anatomic relationship between cerebral cortices and lesions for planning neurosurgical operation were evaluated. Finally, we compared post-operative neurologic function with pre-operative neurologic function in same patients. RESULTS: The fMRI examination was successful in identifying the functional cortices and depicting anatomic relationship between functional cortices and lesions in all patients. In nine patients of 11 patients with identified sensorimotor cortices, postoperative grade of manual motor test was not changed, compared with preoperative grade. Whereas postoperative improved than preoperative grade in one patient of remaining two patients, postoperative aggravated than preoperative grade in the other. This result was due to atherosclerotic lacunar infarction, regardless of tumor resection. Postoperative deficit of language function was not found in seven patients with identified language cortices. CONCLUSION: fMRI could be a helpful method for determining the best approach to neurosurgical treatment in patients with brain tumors in or around sensorimotor or language cortices.

Syringomyelia Associated with Posterior Fossa Tumor: Case Report

The authors describe three patients of syringomyelia associated with posterior fossa tumor. The lesions were diagnosed by magnetic resonance imaging. Total removal of tumor without decompression of foramen magnum was done and regression of syringomyelia and improvement of symptoms were demonstrated. It is suggested that the blockage of cerebrospinal fluid flow at the foramen magnum by tonsilar herniation may play an important role in syrinx formation.

Outcome of Endoscopic Third Ventriculostomy

OBJECTIVE: The authors review 17 cases of obstructive hydrocephalus treated with endoscopic third ventriculostomy to elucidate the adequate age, indication, surgical technique and radiologic criteria. METHODS: From March 1998 to August 2002, 17 endoscopic third ventriculostomies were performed(11 male and 6 female patients). The operation records and neuroimaging studies of the patients were reviewed retrospectively. RESULTS: The age of the patients ranged from 2 months to 70 years(mean age 21 years). Hydrocephalus was caused by aqueductal stenosis in 8 patients, tumor in 8(pineal mass: 5, cystic mass in third ventricle: 2 cerebellar mass: 1), cavernous angioma in 1. The overall success rate was 64.7%(11/17). In the present study, the preoperative increased intracranial pressure symptom was a reliable indicator of surgical outcome. The lateral ventricular size and the III ventricle width reduction, the presence of a signal void on the third ventricle floor appeared to correlate with clinical success. But the cystic mass in the third ventricle was less likely to benefit. Complications were bleeding in 3, infections in 2 and transient III and VI nerve palsy in one case, but there was no permanent morbidity or mortality. CONCLUSION: Endoscopic third ventriculostomy is a safe, simple, effective alternative treatment option of obstructive hydrocephalus in appropriate patient selection.

Prognostic Factors in Patients with Brain Metastases

OBJECTIVE: Prognostic factors in 92 patients with brain metastases, treated in our hospital, are identified in order to determine subgroups of patients suitable for selection in future trials. METHODS: From January 1985 through March 1998, 117 patients with computed tomography(CT) or magnetic resonance(MR) image diagnosed brain metastases were referred to our department. The follow-up data of 92 cases were available in this study. One half of the patients were treated with conservative treatment(53.2%), the remainder were treated with surgery alone or surgery with radiation therapy. Information on potential prognostic factors was collected, and then univariate analysis was performed to determine significant prognostic factors. RESULTS: Overall median survival was 7.6 months, with 1-month, 1-year, and 2-year survival rates of 92.4%, 32.9% and 17.9% respectively. Age, performamce status and primary tumor treatment were significant prognostic factors on survival. Number and treatment modality of brain metastases were also identified as prognostic factors. Median survival in patients conservatively treated with steroid alone or with radiotherapy was significantly different from that in patients treated with surgery(p=0031). CONCLUSION: Age(80), number of brain metastases(single), treatmet modalities of primary tumor and brain metastases(surgical treatment) appeared to be statistically significant prognostic factors. These prognostic factors could be helpful to determine subgroups of patients suitable for selection in future trials.

Intracranial Hemorrhage from Pilocytic Astrocytoma in Pons

We report a case of brain-stem glioma with hemorrhage. A 24-year-old female presented with a 2-month history of headache, vomiting, right hemiparesis. Magnetic resonance image showed a 4X2.5cm sized mass with subacute stage hemorrhage in the left cerebellopontine angle. The mass and hemorrhage was surgically removed and pathological findings were consistent with pilocytic astrocytoma with recent hemorrhage. The patient discharged with mild neurological deficit.

Simultaneous Occurrence of Subarachnoid Hemorrhage due to Ruptured Aneurysm and Remote Hypertensive Intracerebral Hemorrhage: Case Report

Simultaneous occurrence of aneurysmal subarachnoid hemorrhage (SAH) and hypertensive intracerebral hemorrhage (ICH) is very rare and only two cases have been previously reported in the literatures. We present a case of 68-yr-old man with a history of untreated hypertension, who suffered from sudden onset of headache followed by right hemiparesis. Computed tomographic (CT) scan revealed SAH in the basal cistern and remote ICH at the left putamen. Cerebral angiography showed a saccular aneurysm at the anterior communicating artery. No other vascular anomaly could be found at left putaminal area. Nine days after the ictal attack of SAH, the neck of aneurysm was clipped via the left frontotemporal craniotomy. Because of the ICH at the left frontal lobe and intraventricular hematoma on postoperative CT, we performed hematoma removal and external ventricular drainage 3 hours after the first operation. Postoperative neurological status had been improved to be drowsy and he was discharged in a severely disabled state 4 weeks after surgery. We suggest that the rupture of aneurysm possibly caused a rapid increase in blood pressure and subsequently resulted in hypertensive ICH.

Uniportal Endoscopic Thoracic Sympathicotomy for Primary Hyperhidrosis

OBJECTIVE: Endoscopic thoracic sympathectomy is an effective procedure for primary hyperhidrosis. The author present a retrospective analysis of uniportal endoscopic thoracic sympathicotomy for primary hyperhidrosis. METHODS:P Twenty patients underwent bilateral uniportal endoscopic sympathicotomy since August 1999. After collapsing the lung, a 6mm skin incision was made at the third intercostal space in anterior axillary line or just behind the posterior border of the pectoralis major and perforated with operating sheath. The endoscopy was 6.5mm in diameter and has one working channel(Karl Storz). An insulated 2mm coagulating forceps was introduced and T1-2 sympathicotomy with(13 patients) or without T2-3 sympathicotomy(7 patients) was performed. After the lung was fully inflated, the scope and the operating sheath were removed without chest tube, followed by single stitch. RESULTS: Both sides were usually done within twenty minutes in a single stage. There was no postoperative complication except one case of pneumothorax and nineteen patients discharged at the following morning. Nineteen patients were satisfied with immediate and permanent relief of palmar perspiration. Recurrence of palmar hyperhidrosis has been noticed in one patient who underwent T1-2 sympathicotomy only, but the symptom was not so severe. There was no surgical mortality. CONCLUSION: The results of endoscopic sympathicotomy in patients suffering from severe palmar and axillary hyperhidrosis are favorable. Single-port technique is enough for the successful sympathicotomy with less postoperative discomfort and scars.

Study on the Protective Effects of 6R-Tetrahydrobiopterin on the Oxidative Neuronal Injury in Mouse Cortical Cultures

OBJECTIVE: 6R-Tetrahydrobiopterin(BH4) is a cofactor for the aromatic amino acid hydroxylases which is essential for the biosynthesis of catecholamines and serotonin. It also acts as a cofactor for nitric oxide synthase, and stimulates the release of some neurotransmitters such as dopamine, serotonin, acetylcholine and glutamate. Recently, it has been reported that BH4 could induce cellular proliferation and enhance neuronal survival. This study was performed to investigate the antioxidative effect of BH4 on the various oxidative insults in mouse cerebral cortical cell cultures. METHODS: Iron ion(FeCl2), zinc ion(ZnCl2), sodium nitroprusside(SNP) and buthionine sulfoximine(BSO, a glutathione depletor) were used as oxidants. Cell death was assessed by measurement of lactate dehydrogenase efflux to bathing media at the end of exposure. RESULT: All 4 oxidants induced neuronal cell death associated with cell body swelling, which was markedly inhibited by trolox(100nM), a vitamin E analog. BH4(10-100nM) markedly inhibited the neuronal cell death induced by all 4 oxidants(20nM Cu2+, 20nM Zn2+, 1nM SNP or 1mM BSO). However, BH4 failed to inhibit the neuronal cell death induced by 24hr exposure to 20nM NMDA. CONCLUSION: These results suggest that BH4 has antioxidative action independently of any actions of enzyme cofactor.

The Variation of Position of the Conus Medullaris in Korean Adults - A Magnetic Resonance Imaging Study -

OBJECTIVES: There have been several studies documenting the changing level of the conus throughout infancy and childhood, but there is only a little detailed study that documents the range of conus positions in a living adult population, especially in Korean, without spinal deformity. METHODS: we made a sequential study of magnetic resonance images of the lumbar spine to determine the variation in position of the conus medullaris in 650 living korean adults population without spinal deformity who checked MRI to identify the cause of low back pain. The study population consisted of patients over the age of 16 years. A T1-weighted, midline, sagittal image was reviewed for identifying the postion of conus. This location was recorded in relation to the upper, middle, or lower third of the adjacent vertebral body or the adjacent intervertebral disc. RESULTS: The study group consisted of 305 men(47%) and 345 women(53%) with a mean age 45.9 years(range, 16-79 years). The conus existed commonly at the middle third of L1(131cases, 20.2%), at the L1-2 intervertebral space(129cases, 19.8%), and the lower third of L1(123cases, 18.9%). The mean position of conus was the lower third of L1(range, middle third of T12 to middle third of L3). Conclusions:The mean position of conus was at the lower third of L1(range, middle third of T12 to middle third of L3). This results was same as that of foreign study. Our results of living korean adult population could allow for safe clinical procedures such as lumbar puncture, spinal anesthesia, and help to explain the differences among observed neurologic injuries from fracture-dislocation at the thoracolumbar junction.

Results of Microvascular Decompression in Hemifacial Spasm

OBJECTIVES: Hemifacial spasm is painless uncommon disorder characterized by involuntary paroxysmal movement on one side of face. It is known that hemifacial spasm is mainly due to pulsatile compression by vessels at the root exit zone(REZ) of the facial nerve. Microvascular decompression at REZ of the facial nerve has become the standard treatment modality for hemifacial spasm. The authors have analized patients with hemifacial spasm treated with microvascular decompression to evaluate operation result and clinical course after operation. PATIENTS AND METHODS:From 1992 to 1999, 41 patients with hemifacial spasm underwent this operation. Retrospective analysis of operation results and clinical recovery patterns was done. The length of observation had been more than 6 months in all cases. RESULTS: The ratio of male to female was 1: 1.4, and age at operation ranged from 24 to 66 years. Their mean age was 47.6 years and the mean preoperative duration of symptoms was 7.2 years. Most common offending vessels were AICA in 18 cases(48%) and second most common were PICA in 13 cases(31.7%). The rest of them were 3 case in vertebral artery, and 7 cases(13%) in multiple offending vessels. Patterns of improvement after surgery could be divided into 4 clinical types. There was complete recovery in 3 days after operation in 24 cases(58.6%, Immediate complete recovery). There was complete recovery in 3 days after operation, and symptom was recurred partially, which was gradually subsided in 2 weeks after operation in 4 cases(9.8%, Delayed complete recovery type I). There was partial recovery after operation and symptom was compretely disappeared gradually in 6 months after operation in 7 cases(17.1%, Delayed complete recovery type II). Finally, there was partial recovery after operation, and symptom was somewhat remained after 6 months later(14.5%, Delayed partial recovery). CONCLUSION: In conclusion, microvascular decompression for hemifacial spasm is a safe and reliable treatment modality with good results of improvement and there are 4 recovery patterns in clinical course after operation in our series. Therefore, follow-up observation after microvascular decompression is necessary to evaluate the operative results and complication, especially in the delayed resolved cases.