Target temperature management in traumatic brain injury with a focus on adverse events, recognition, and prevention.

Traumatic brain injury (TBI) is a critical cause of disability and death worldwide. Many studies have been conducted aimed at achieving favorable neurologic outcomes by reducing secondary brain injury in TBI patients. However, ground-breaking outcomes are still insufficient so far. Because mild-to-moderate hypothermia (32°C-35°C) has been confirmed to help neurological recovery for recovered patients after circulatory arrest, it has been recognized as a major neuroprotective treatment plan for TBI patients. Thereafter, many clinical studies about the effect of therapeutic hypothermia (TH) on severe TBI have been conducted. However, efficacy and safety have not been demonstrated in many large-scale randomized controlled studies. Rather, some studies have demonstrated an increase in mortality rate due to complications such as pneumonia, so it is not highly recommended for severe TBI patients. Recently, some studies have shown results suggesting TH may help reperfusion/ischemic injury prevention after surgery in the case of mass lesions, such as acute subdural hematoma, and it has also been shown to be effective in intracranial pressure control. In conclusion, TH is still at the center of neuroprotective therapeutic studies regarding TBI. If proper measures can be taken to mitigate the many adverse events that may occur during the course of treatment, more positive efficacy can be confirmed. In this review, we look into adverse events that may occur during the process of the induction, maintenance, and rewarming of targeted temperature management and consider ways to prevent and address them.

Clinical Utility of Angiographic CT with a Flat-detector Angiographic System during Endovascular Procedure.

OBJECTIVE: We evaluated the feasibility of angiographic computed tomography (ACT) for visualizing stent material in patients who underwent intracranial or extracranial stent placement to treat atherosclerotic lesions or stent assisted coil embolization. MATERIALS AND METHODS: We performed intrarterial and intravenous ACT on biplane angiography system equipped with flat panel detectors (Axiom Arits dBA; Siemens Medical Solutions, Forchheim, Germany). Vistipaque 320 was injected for contrast medium, total 150 mL at flow rate of 5 mL/s through artery and 77 mL at flow rate of 3.5 mL/s through vein. RESULTS: ACT is a new imaging modality that provides a clear visualization of stent strut. CONCLUSION: Therefore this new application has potential to become the noninvasive option for follow-up after endovascular surgery using stents.

Treatment Strategies to Attenuate Perihematomal Edema in Patients With Intracerebral Hemorrhage.

Spontaneous intracerebral hemorrhage (SICH) continues to be a significant cause of neurologic morbidity and mortality throughout the world. Although recent advances in the treatment of SICH have significantly decreased mortality rates, functional recovery has not been dramatically improved by any intervention to date. There are 2 predominant mechanisms of brain injury from intracerebral hemorrhage: mechanical injury from the primary hematoma (including growth of that hematoma), and secondary injury from perihematomal inflammation. For instance, in the hours to weeks after SICH as the hematoma is being degraded, thrombin and iron are released and can result in neurotoxicity, free radical damage, dysregulated coagulation, and harmful inflammatory cascades; this can clinically and radiologically manifest as perihematomal edema (PHE). PHE can contribute to mass effect, cause acute neurologic deterioration in patients, and has even been associated with poor long-term functional outcomes. PHE therefore lends itself to being a potential therapeutic target. In this article, we will review 1) the pathogenesis and time course of the development of PHE, and 2) the clinical series and trials exploring various methods, with a focus on minimally invasive surgical techniques, to reduce PHE and minimize secondary brain injury. Promising areas of continued research also will be discussed.

Risk Factors for Early Hemorrhagic Progression after Traumatic Brain Injury: A Focus on Lipid Profile.

The purpose of this study was to identify the risk factors related to the hemorrhagic progression (HP) of brain contusion in patients after traumatic brain injury (TBI). Recently, many studies have reported abnormal lipid levels associated with hemorrhagic stroke. Unlike hemorrhage stroke, however, the lipid profiles in patients with TBI have not been examined. Therefore, we evaluated the risk factors of HP in patients with TBI and focused on lipid profiles. Fifty-six patients with TBI with mild to moderate injuries (Glasgow Coma Scale ≥9) who initially did not need surgical intervention were enrolled in this study. Patients underwent repeated computed tomography (CT) scans at 4 h and 24 h after injury. Magnetic resonance imaging (MRI) was performed 7 days after the initial injury. In each noncontrast CT scan, the hemorrhage volume was quantified using the ABC/2 technique. Clinical features, previous medical history, initial CT, and microbleeding on follow-up MRI were analyzed retrospectively. There were 31 (55%) patients in whom significant HP developed (volume >30%). Current smoking (p=0.034), higher initial systolic blood pressure (p=0.035), and lower triglyceride levels (p=0.039) were significantly associated with HP. Current smoking and a triglyceride (TG) level <150 mg/dL were the only statistically significant predictors of HP in the multivariate analysis (p=0.019, p=0.021, respectively). HP with TBI is common in patients who currently smoke and have lower TG levels (150 mg/dL). These patients should be monitored closely, and surgery may be considered before deterioration occurs.

Metastatic Brain Neuroendocrine Tumor Originating from the Liver.

A 67-year-old male presented with left temporal hemianopsia and left hemiparesis. A contrast-enhanced magnetic resonance image revealed a 4.5×3.5×5.0 cm rim-enhancing mass with central necrosis and associated edema located in the left occipital lobe. Of positron emission tomography and abdominal computed tomography, a 9-cm mass with poor enhancement was found in the right hepatic lobe. Craniotomy and right hemihepatectomy was performed. The resected specimen showed histological features and immunochemical staining consistent with a metastatic neuroendocrine tumor (NET). Four months later, the tumors recurred in the brain, liverand spinal cord. Palliative chemotherapy with etoposide and cisplatin led to complete remission of recurred lesions, but the patient died for pneumonia. This is the first case of a metastatic brain NET originating from the liver. If the metastatic NET of brain is suspicious, investigation for primary lesion should be considered including liver.

Rapid Growing Eosinophilic Granuloma in Skull after Minor Trauma.

The authors present a case of rapidly progressing eosinophilic granuloma (EG) of the skull without hemorrhage after minor trauma. A 6-year-old boy presented with a soft mass on the midline of his forehead. He had a surgery for EG 19 months ago. One month earlier, computed tomography (CT) and bone scans were performed to evaluate the possible recurrence of EG, and there was no evidence of recurrence in CT. However, a slightly increased uptake in the bone scan was noted on the midline of the forehead. A rapid growing mass developed in a new spot after a minor trauma 7 days before the patient arrived at the clinic. His physical examination was unremarkable, except for a non-tender, soft, and immobile mass. A plain skull X-ray and CT showed a lytic bony defect on the midline of the frontal bone. Magnetic resonance imaging showed a 1.4 cm sized enhancing mass. Surgical resection and cranioplasty were done. The role of trauma in the development of EG is unclear. However, our case suggests that minor trauma is an aggravating factor for EG formation. Careful observation with regular follow-up is necessary in patients with EG after minor trauma.

Predictors of malignant brain edema in middle cerebral artery infarction observed on CT angiography.

Patients with middle cerebral artery (MCA) infarction accompanied by MCA occlusion with or without internal carotid artery (ICA) occlusion have a poor prognosis, as a result of brain cell damage caused by both the infarction and by space-occupying and life-threatening edema formation. Multiple treatments can reduce the likelihood of edema formation, but tend to show limited efficacy. Decompressive hemicraniectomy with duroplasty has been promising for improving functional outcomes and reducing mortality, particularly improved functional outcomes can be achieved with early decompressive surgery. Therefore, identifying patients at risk for developing fatal edema is important and should be performed as early as possible. Sixty-four patients diagnosed with major MCA infarction with MCA occlusion within 8 hours of symptom onset were retrospectively reviewed. Early clinical, laboratory, and computed tomography angiography (CTA) parameters were analyzed for malignant brain edema (MBE). Twenty of the 64 patients (31%) had MBE, and the clinical outcome was poor (3month modified Rankin Scale >2) in 95% of them. The National Institutes of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early Computed Tomography Score, Clot Burden Score, and Collateral Score (CS) showed statically significant differences in both groups. Multivariable analyses adjusted for age and sex identified the independent predictors of MBE: NIHSS score >18 (odds ratio [OR]: 4.4, 95% confidence interval [CI]: 1.2-16.0, p=0.023) and CS on CTA <2 (OR: 7.28, 95% CI: 1.7-30.3,p=0.006). Our results provide useful information for selecting patients in need of aggressive treatment such as decompressive surgery.

Analysis of the factors affecting graft infection after cranioplasty.

BACKGROUND: The predictors of graft infection after cranioplasty (GIC) following decompressive craniectomy are not well established. Knowledge of the risk factors for GIC will allow development of preventive measures designed to reduce infection rates. Therefore, the objective of this study was to identify risk factors for the development of GIC. METHODS: A total of 85 patients underwent reconstructive cranioplasty after decompressive craniectomy between January 2009 and July 2011 and had a follow-up period of > 1 year; charts were reviewed retrospectively. Although autograft was used whenever possible, artificial bone was used for cranioplasty. GIC was defined as infection requiring removal of the bone graft. RESULTS: GIC occurred in six patients (7.05 %). GIC was not related to the indications for craniectomy, the interval of cranioplasty, graft material, or the size of the bone defect (p = 0.433, p = 0.206, p = 0.665, and p = 0.999, respectively). The GIC rate was significantly related to previous temporalis muscle resection, preoperative subgaleal fluid collection, operative times > 120 min, and postoperative wound disruptions (p = 0.001, p < 0.001, p = 0.035, and p = 0.016, respectively). Multiple logistic regression showed that the presence of a subgaleal fluid collection before cranioplasty significantly increased the risk of GIC (OR: 38.53; 95 % CI: 2.77-535.6; p = 0.006). CONCLUSIONS: The results of this study suggest that long operative times (> 120 min), craniectomy with temporalis muscle resection, the presence of preoperative subgaleal fluid collection, and postoperative wound disruption may be risk factors for graft infection after cranioplasty. Surgical techniques should be developed to reduce operative time and to avoid temporalis muscle resection when possible. In addition, meticulous dural closure aimed at reducing the formation of subgaleal fluid collection is important for the prevention of graft infections after cranioplasty.

A new possible mechanism of hearing loss after microvascular decompression for hemifacial spasm.

OBJECTIVE: Hearing loss is a well-known complication that may occur during microvascular decompression (MVD) for hemifacial spasm (HFS). Cause and risk factors are highly variable. We present cases of hearing loss induced by saline overinfusion after MVD. STUDY DESIGN: Retrospective review in a tertiary referral center. INTERVENTION: Three hundred thirty-one patients with HFS underwent MVD from March 2009 to October 2010. MAIN OUTCOME MEASURES: Brain stem auditory evoked potential (BAEP) was monitored during the surgery. Before completion of the dural closure, the surgical field was routinely filled with warm saline to avoid postoperative pneumocephalus and epidural hematoma. RESULTS: Seven patients experienced a change in wave V amplitude and latency after the dural closure. In 2 patients, the amplitudes decreased by less than 50%, and latencies were delayed by less than 1.0 ms, ipsilaterally in 1 patient and contralaterally in the other. In 1 patient, decreased amplitude and delayed latency appeared bilaterally with more severity on the operated side, accompanied by delayed ipsilateral permanent hearing loss. In 4 of the 7 patients, an ipsilateral response of BAEP was completely absent. Of these 4 patients, 2 experienced permanent hearing loss, and another 2 patients who underwent dural reopening and saline drainage had restoration of their normal hearing. CONCLUSION: Intradural compression due to overinfusion of saline may lead to postoperative hearing loss, although the incidence is low, and immediate decompression by drainage may be required.

Treatment of a traumatic leptomeningeal cyst in an adult with fibrinogen-based collagen.

Reports of traumatic leptomeningeal cysts (TLMC) are rare in adults. The standard treatment approach is craniectomy with careful exposure of the intact dural edges, followed by duroplasty. However, occasionally, the location of the TLMC makes achieving watertight duroplasty impossible. Herein, we report the case of a 28-year-old male who presented with a soft growing mass on the vertex of his head 16 months after the head trauma. Upon enhanced CT examination, a bony defect involving both the inner and outer table of the cranium was observed close to the sagittal sinus, and a well-defined cystic mass, 5 cm in diameter, was nested within the defect. The risks associated with extension craniotomy were high because the lesion was located superficial to the sagittal sinus, we opted to use fibrinogen-based collagen fleece (TachoCombR®) to repair the dural defect. Two months after surgery, the patient remained asymptomatic with a good cosmetic result. In cases like ours, when the defect is near the major sinuses and the risk of rupturing the sinus during watertight dural closure is high, fibrinogen-based collagen fleece (TachoComb®) is an effective alternative approach to standard dural suture techniques.

Long-term prognostic factors for microvascular decompression for trigeminal neuralgia.

The purpose of this retrospective study was to identify preoperative imaging characteristics and surgical findings that predict pain relief after microvascular decompression (MVD) for trigeminal neuralgia (TN). This study included 141 patients with follow-up ranging from 6 months to 10 years (mean follow-up=26.3 months). Preoperative images were assessed in 90 patients who were evaluated with constructive interference in steady-state (CISS) MRI in the last 6 years. These findings were compared with the severity of neurovascular conflict (NVC) found at operation to identify imaging findings useful for prognosis. Using Kaplan-Meier analysis, we found that the success rate of MVD was 91.1 ± 2.5% at 1 year and was 76.3 ± 7.5% after 5 years. A higher degree of NVC at operation (p=0.000), no vein compression (p=0.049) and single vessel compression (p=0.000) were good prognostic factors for pain relief. Two meaningful positive MRI findings, specifically, the "cerebrospinal fluid rim sign" and the "deviation sign" were statistically significantly associated with the severity of NVC at operation and MVD success (p=0.000). In this study, 34 patients (24.1%) complained of facial numbness postoperatively, and the oral herpes simplex virus was reactivated in 19 patients (13.4%). The involvement of a single arterial offender in NVC is the most important prognostic factor for MVD in TN, and the positive MRI findings described in this report may be helpful in selecting patients for MVD.

Meningeal supratentorial hemangioblastoma in a patient with von hippel-lindau disease mimicking angioblastic menigioma.

Hemangioblastomas are sporadic tumors found in the cerebellum or spinal cord. Supratentorial hemangioblastomas are rare, and those with meningeal involvement are extremely rare and have been reported in only approximately 130 patients. Here, we report the case of a 51-year-old female patient with supratentorial meningeal hemangioblastoma detected 5 years after surgical resection of an infratentorial hemangioblastoma associated with von Hippel-Lindau disease. Patients with von Hippel-Lindau syndrome are at risk for developing multiple hemangioblastomas, with new tumor formation and growth and possible meningeal infiltration. Regular lifelong follow-up in at-risk patients is recommended and should include the differential diagnosis of dural-based tumors such as angioblastic meningioma and metastatic renal cell carcinoma.

Microvascular decompression for hemifacial spasm: long-term outcome and prognostic factors, with emphasis on delayed cure.

The postoperative course of microvascular decompression (MVD) for hemifacial spasm (HFS) is variable, and the optimal time for assessing the results is unclear. From April 1997 to October 2007, MVD for HFS was performed in 801 patients. Patients were divided into two groups (cured or failed) according to subjective patient assessments over a 3-year period. We analyzed patient characteristics and surgical findings to determine prognostic factors. Medical records were analyzed retrospectively over the 3-year follow-up period. Of the 801 patients who underwent surgery, 743 (92.8 %) appeared to be cured, 70 (8.7 %) had residual or recurrent spasms more than 1 year after surgery, 11 (1.3 %) had gradual improvement over 3 years, and 1 (0.1 %) had delayed improvement more than 3 years after surgery. Fifty-eight patients (7.2 %) had residual or recurrent spasms more than 3 years after surgery, of which 19 (2.4 %) had recurrence after initial relief. The mean time to spasm recurrence was 18.9 months. Intraoperative resolution of the lateral spread response (LSR) after decompression (p = 0.048) and severe indentation (p = 0.038) were significant predictors of good long-term outcome after MVD for HFS. In our series, 70 patients (8.7 %) had residual or recurrent spasms more than 1 year after surgery, of which 12 (17.1 %) improved gradually after 1 year. If the surgeon can confirm intraoperative resolution of the LSR and severe indentation, reoperation can be delayed until 3 years after MVD.

Treatment outcomes of pediatric craniopharyngioma : a 15-year retrospective review of 35 cases.

OBJECTIVE: The aim of this study was to describe a single center's experience in the management of craniopharyngiomas in children over a 15-year period. METHODS: The clinical records of pediatric patients treated for craniopharyngiomas between December 1995 and February 2011 were reviewed. Thirty-five pediatric patients diagnosed with craniopharyngioma were treated, and their medical records and imaging data were analyzed retrospectively. RESULTS: The mean follow-up duration was 76 months (range, 10-195). Overall survival and local control rates at 10 years were 94.7±5.1% and 37.1±11.9%, respectively. The female-to-male ratio was 16 : 19, and the mean age was 8.6 years (range, 1-17). Initially, gross total resection (GTR) was performed in 30 patients; subtotal resection (STR) followed by radiotherapy was performed in 5 patients. Of the 14 cases that showed recurrence after GTR, 5 patients were treated with GTR, 1 with radiation therapy (RT), 4 with gamma knife radiosurgery (GKRS), and 4 with subtotal resection followed by RT. No patients who underwent RT or GKRS had recurrences. Two cases with recurrence after STR followed by RT were treated with GTR. One patient died of hormonal insufficiency 64 months after the first surgery. The overall median time progression was 51.2 months (range, 3-182) : 49.7 months in the patients who underwent GTR and 60.2 months in the patients who underwent STR followed by RT. CONCLUSION: If safe resection is possible, GTR at the initial treatment should be attempted to reduce the tumor recurrence. However, if the tumor recurs after the first surgery, RT or GKRS with/without reoperation may be an effective salvage treatment for recurrent craniopharyngioma.

Using the new clinical grading scale for quantification of the severity of hemifacial spasm: correlations with a quality of life scale.

BACKGROUND: To date, no consensus has been reached regarding validated and practical tools to quantify the severity of hemifacial spasm (HFS) before and after surgery. OBJECTIVE: The aim of this study has been to establish objective parameters for determining the preoperative severity of HFS and to assess the correlation with quality of life (QoL) in HFS patients. METHODS: Patients who experienced HFS between April and August 2010 were reviewed. The patients were divided into four groups according to the severity of spasm (SMC grade): grade I - localized spasm around the periocular area; grade II - involuntary movement spreads to other parts of the ipsilateral face and it affects other muscle groups, i.e. the orbicularis oris, zygomaticus, frontalis or platysma muscle; grade III - interference with vision because of frequent tonic spasms, and grade IV - disfiguring asymmetry. We interviewed each patient using an HFS-7 questionnaire containing a short self-rating QoL scale. We estimated the measure of agreement across observers and examined the relationships between SMC grade and other factors, including HFS-7 responses. RESULTS: Preoperative evaluation using the SMC grading system showed 25 patients with grade I, 48 patients with grade II, 33 patients with grade III, and 12 patients with grade IV HFS. The HFS-7 scores indicating QoL were 9 (range: 0-17) in grade I, 12 (range: 1-25) in grade II, 16 (range: 2-23) in grade III, and 17 (range: 3-24) in grade IV subjects. SMC grade was correlated with symptom duration (p < 0.0001) and HFS-7 score (p = 0.02). In addition, higher SMC grade was closely associated with longer duration of persisting symptoms (p < 0.05). CONCLUSIONS: An SMC grading system is useful as a means of quantifying spasms to allow for more precise descriptions of a patient's condition including QoL, and to improve the accuracy of communication between medical teams.

The role of radiosurgery in patients with brain metastasis from small cell lung carcinoma.

OBJECTIVE: The purpose of this retrospective study was to evaluate the outcome of gamma knife radiosurgery (GKRS) and/or whole brain radiation therapy (WBRT) for the treatment of small cell lung carcinoma (SCLC) metastasis to the brain. METHODS: From 2000 to 2010, 50 patients underwent GKRS for metastatic brain lesions originating from SCLC. Among these patients, 11 received prophylactic cranial irradiation (PCI) before the development of metastatic lesions (PCI group), and GKRS was performed as an initial treatment for newly diagnosed lesions in 12 patients who had not received PCI (primary GKRS group). In addition, GKRS was performed as a salvage treatment for progressive lesions after WBRT in 27 patients (salvage GKRS group). The medical records and imaging data of all patients were retrospectively analyzed. RESULTS: The overall survival of the 50 patients was 20.8 months (range 1-53) after the diagnosis of primary tumor and 12.0 months (range 1-47) after the development of cerebral metastasis. Median survival after GKRS was 4.8 months (range 1-15) in the PCI group, 4.6 months (range 0-18) in the primary GKRS group, and 7.6 months (range 0-33) in the salvage GKRS group. Further treatment for progressive lesions after GKRS was necessary in 15 patients, after a mean interval of 3.8 months. Causes of death were systemic organ failure in 15 patients, deterioration of neurological state in 13 patients, and unknown or combined causes in 16 patients. The local control rate of the lesions treated with GKRS was 76.4% (decreased in 13 patients and stable in 16 patients at the final imaging follow-up (mean 5.60 months). CONCLUSION: GKRS is an effective local treatment for brain metastasis from SCLC both as an initial treatment for newly diagnosed lesions after PCI and as a salvage treatment for recurrent or progressive lesions. However, the survival benefit is not significant because most patients die of systemic multi-organ failure with a short life expectancy.

Microsurgical resection of deep-seated lesions using transparent tubular retractor: pediatric case series.

BACKGROUND: To facilitate effective resection of deep-seated brain lesions without causing significant trauma to the overlying cortex, the authors used a transparent plastic tubular retractor to approach these lesions. METHODS: Between July 2009 and January 2011, we used an 11-mm diameter transparent plastic tubular retractor in combination with a frameless stereotactic navigation system to remove 18 deep lesions. RESULTS: Gross total resection of the lesions was achieved in 14 of 18 patients, and subtotal removal occurred in four patients. Effective resection of lesions was achieved in all patients through small size craniotomy window and small cortical incision. The histopathologic diagnosis was established in all 18 patients: 3 hematomas, 3 cavernous angioma, 7 low-grade glioma, 2 dysembryoplastic neuroepithelial tumor, 1 choroid plexus papilloma, 1 abscess, and 1 meningioma. CONCLUSION: Microsurgery using a transparent tubular retractor guided by a neuronavigation system facilitated accurate and effective removal of these deep-seated brain lesions.

Efficacy of endoport-guided endoscopic resection for deep-seated brain lesions.

Surgery for deep-seated brain lesions without causing significant trauma to the overlying cortex is difficult because brain retraction is required to approach these lesions. The aim of this study was to determine the efficacy of endoport-guided endoscopic or microscopic removal for deep-seated lesions using the neuronavigation system. Between October 2008 and December 2009, 21 patients (17 men and 4 women; average age, 40.8 years) underwent endoport-guided endoscopic tumor removal. We adapted the transparent tubular conduit, so-called "endoport," to target the lesions under the guidance of neuronavigation. We then determined the efficacy and limitations of this technique with fully endoscopic removal, compared with standard approaches using a spatula retractor. Gross total resection of the lesions was achieved in 14 of 21 patients (66%), and partial removal occurred in four (19%) patients. However, there was failure to remove the lesion through the endoport in three patients (14.3%), requiring the use of blade spatula retractors. In reviewing the seven cases with either failure or partial removal, it was found that a large tumor size (≥ 3 cm) and calcified lesions were the major factors limiting the application of this technique. Endoport-guided endoscopic surgery facilitated an accurate and minimally invasive technique for removal of these deep-seated brain lesions. This procedure required a protracted learning curve although, when successful, this approach can minimize brain retraction and provide satisfactory visualization.

Metronidazole-induced encephalopathy in a patient with infectious colitis: a case report.

INTRODUCTION: Encephalopathy is a rare disease caused by adverse effects of antibiotic drugs such as metronidazole. The incidence of metronidazole-induced encephalopathy is unknown, although several previous studies have addressed metronidazole neurotoxicity. Here, we report the case of a patient with reversible cerebellar dysfunction on magnetic resonance imaging, induced by prolonged administration of metronidazole for the treatment of infectious colitis. CASE PRESENTATION: A 71-year-old Asian man, admitted to our hospital with hematochezia, underwent Hartmann's operation for the treatment of colorectal cancer three years ago. He was diagnosed with an infectious colitis by colonoscopy. After taking metronidazole, he showed drowsiness and slow response to verbal commands. Brain magnetic resonance imaging showed obvious bilateral symmetric hyperintensities within his dentate nucleus, tectal region of the cerebellum, and splenium of corpus callosum in T2-weighted images and fluid attenuated inversion recovery images. Our patient's clinical presentation and magnetic resonance images were thought to be most consistent with metronidazole toxicity. Therefore, we discontinued metronidazole, and his cerebellar syndrome resolved. Follow-up magnetic resonance imaging examinations showed complete resolution of previously noted signal changes. CONCLUSION: Metronidazole may produce neurologic side effects such as cerebellar syndrome, and encephalopathy in rare cases. We show that metronidazole-induced encephalopathy can be reversed after cessation of the drug. Consequently, careful consideration should be given to patients presenting with complaints of neurologic disorder after the initiation of metronidazole therapy.

The patterns and risk factors of hearing loss following microvascular decompression for hemifacial spasm.

OBJECTIVE: The aim of this study was to reveal the risk factors including intraoperative brain stem auditory evoked potential (BAEP) changes and to define parameter and warning values of BAEP beyond which the probability of hearing impairment rises significantly. METHODS: From April 1997 to February 2009, 1156 patients underwent microvascular decompression (MVD) for hemifacial spasm (HFS) and their medical records and audiologic data. The intraoperative BAEP monitoring was performed in all operations during surgery from the time of administration of general anesthesia until the time of skin closure. Pure tone audiometry (PTA) and Speech Discrimination Score (SDS) were performed on all patients before and after surgery for categorizing the patterns of hearing loss. There were 825 females and 331 males with a mean age of 48.7 years (range 17-75 years). The mean symptom duration was 67.8 months (range 1-420 months). RESULTS: At the 1-year follow-up examination, 1091 (94.4%) patients of the total 1156 patients exhibited a cured state, and 65 (5.6%) patients had residual spasms. Hearing loss occurred in 46 patients (3.9%). In 26 patients, PTA was decreased more than 15 dB with a proportional decrease of the SDS. In 10 patients, poor SDS without hearing loss occurred. Total deafness was developed in 10 patients. A higher incidence of BAEP change and a poor recovery especially amplitude in wave V during surgery was observed in patients with poor SDS (eight patients) and total deafness (seven patients) (p = 0.000). Reduction of amplitude more than 50% in wave V was a strong indicator for a worse outcome of the hearing capacity. The difference in other risk factors according to hearing loss pattern was not statistically significant (p > 0.05). Only female was significant (p = 0.005). CONCLUSIONS: The intraoperative BAEP change and a poorer recovery, especially reduction of amplitude more than 50% in wave V, was a strong indicator for a worse outcome of the hearing capacity. Vigilant intraoperative monitoring of the BAEP and adequate steps for recovery of the BAEP change could prevent hearing loss after MVD for HFS.