Stretched and fractured Neuroform Atlas® stent during a stent­assisted coil embolization: A case report.

The Neuroform Atlas® stent is one of the most recently developed stents for coil embolization, with advancements in a lower-profile delivery system, enhanced trackability, smaller cell size, and increased wall conformability. Because of these advantages, the Neuroform Atlas® stent shows high technical success with few procedure-related complications. However, the present study reported a rare complication of a stretched and partially fractured Neuroform Atlas® stent due to unexpected partial withdrawal of microcatheter during deployment for coil embolization of an intracranial aneurysm. The measured length of the stent was ~30 mm, which was greater than the normal length (21 mm). An additional stent was inserted into the distal part of the deployed stent to stabilize the damaged stent and remodel the aneurysm neck. This complication was considered to potentially result from the combination of several factors, including: Curved vessel; open-cell stent; unexpected microcatheter withdrawal during stent deployment; and hooking of the aneurysm selecting microcatheter with stent strut. Understanding the stent design and careful manipulation while avoiding unexpected withdrawal of the microcatheter could prevent this complication.

Direct Cannulation of a Calvarial Diploic Vein for Embolization of a Symptomatic Intraosseous Arteriovenous Fistula: A Case Report.

Diploic arteriovenous fistulas (AVFs) or intraosseous dural AVFs are rare arteriovenous shunts. A diploic AVF is formed between a meningeal artery and an intraosseous diploic vein or the transosseous emissary vein, and the nidus is located exclusively within the bone. Currently, endovascular embolization with a transvenous approach is considered the treatment of choice for most dural AVFs. However, in the absence of an accessible venous channel, an alternate treatment approach should be considered. Herein, we report a case of a diploic AVF that was treated using embolization with transosseous direct cannulation.

Proper Head Rotation when Performing Microvascular Decompression for Hemifacial Spasm: An Orthometric Consideration Based on Preoperative MRI.

BACKGROUND: The classic surgical position for microvascular decompression (MVD) is lateral decubitus with the head rotated 10 degrees away from the affected side. In this study, we measured the angles of the posterior fossa, specifically focusing on the surgical corridors used in MVD surgery for hemifacial spasm (HFS), to identify the proper surgical position. METHOD: The following parameters were assessed on preoperative magnetic resonance images (MRI): petrous angle (PA), sigmoid angle (SA), sigmoid diameter (SD), and root exit zone-sigmoid sinus edge angle (REZ-SEA). RESULTS: The mean PA was 59.7 ± 5.6 degrees, SA was 16.8 ± 8.6 degrees, SD was 13.4 ± 3.5 mm, and the mean REZ-SEA was 59.6 ± 5.8 degrees. The difference between the maximum SA to avoid cerebellar hemisphere injury and the minimum REZ-SEA required to verify the facial nerve REZ is assumed to be the usable range of angles for the operative microscope; the average midpoint of this range was 38.2 ± 6.4 degrees. CONCLUSION: Turning the patient's head 10 degrees away from the affected side was generally appropriate for performing MVD surgery because it provided a mean microscope angle of 48 degrees. However, some patients had corner values for the sigmoid angle, REZ-SEA, and sigmoid sinus diameter. Rotating a patient's head based on precise calculations from preoperative MRI helps to achieve successful surgery.

Treatment for Hemifacial Spasm Associated with a Dissecting Vertebral Artery Aneurysm Requiring Microvascular Decompression in Addition to Endovascular Trapping: A Case Report with Literature Review.

BACKGROUND: The treatment protocol for hemifacial spasm (HFS) associated with dissecting vertebral artery aneurysm (DVAA) has not been established. CASE DESCRIPTION: A-42-year-old man with left HFS underwent endovascular trapping for a DVAA that was identified on brain imaging. Although the dissecting segment was treated successfully, the HFS persisted for 3 months, and subsequently microvascular decompression (MVD) was needed. The posteroinferior cerebellar artery (PICA) was found to be interposed between the root exit zone of the facial nerve and DVAA during surgery. After pulling out the PICA, the HFS ceased immediately. CONCLUSION: HFS associated with DVAA should be considered carefully before formulating a treatment strategy. Moreover, the cause of pulsatile compression may not be visible on brain imaging, and MVD surgery may be indicated in such cases.

The clinical outcomes of mechanical thrombectomy for proximal M1 occlusion involving lenticulostriate perforators: Is it worse than distal M1 occlusion? Retrospective observational study.

ABSTRACT: Although the success rate of recanalization in acute intracranial artery occlusion is high, there is a poor rate of improvement in functional clinical outcome. The purpose of this study was to assess the functional outcome of mechanical thrombectomy for proximal M1 occlusion involving lenticulostriate arteries (LSAs) compared with distal M1 occlusion-sparing the LSAs.A retrospective analysis was conducted in patients with middle cerebral artery (MCA) M1 occlusions who had a successful recanalization subsequent to mechanical thrombectomy. The recanalization results were estimated using the thrombolysis in cerebral infarction grade assessed by digital subtraction angiography. To confirm the ischemic change resulting from the lenticulostriate artery occlusion, we reviewed the neuroimaging findings from magnetic resonance imaging 1 day after mechanical thrombectomy. The functional outcomes were then evaluated using the modified Rankin scale at 90 days.In total, 28 patients with MCA M1 occlusion had successful recanalization outcomes with thrombolysis in cerebral infarction grades IIa, IIb, and III. Among the 28 patients, 17 had proximal M1 occlusions and 11 had distal M1 occlusions. Demographic factors, including initial National Institutes of Health Stroke Scale score, time from symptom to recanalization, and recanalization rate did not differ considerably between patients with proximal and distal M1 occlusions. Regarding infarctions in the basal ganglia, internal capsule, and corona radiata, there were statistically significant differences between the proximal and distal M1 occlusions. However, there were no significant differences in good functional outcome (modified Rankin scale ≤2) observed between the groups at 90 days after mechanical thrombectomy.Although proximal M1 occlusion had more frequent infarctions associated with the LSA territories, these were not related to poor functional outcomes. Both proximal and distal M1 occlusion demonstrated comparably good outcomes.

Rescue balloon-assisted remodeling technique for protrusion of coil loop: A case report.

RATIONALE: Among the possible complications during endovascular embolization of intracranial aneurysms, coil protrusion into the parent artery is associated with parent artery occlusion or thromboembolic of the distal arteries. There is no clearly established management strategy for coil protrusion. This report demonstrates our experience with balloon-assisted remodeling to reposition a protruded coil loop. PATIENT CONCERNS: A 53-year-old man was admitted to our hospital with severe bursting headache, nausea, and vomiting. Computed tomography showed subarachnoid hemorrhage and digital subtraction angiography revealed an anterior communicating artery aneurysm. We decided to obliterate the aneurysm with endovascular embolization using detachable coils. DIAGNOSIS: A small loop protruded into the parent artery during the removal of the microcatheter. INTERVENTIONS: We performed successful repositioning of the protruded coil loop using balloon inflation. CONCLUSION: The rescue balloon-assisted remodeling technique was useful in the management of protrusion of a small coil loop into the parent artery during endovascular coil embolization of an intracranial aneurysm. The procedure was associated with minimal complications.

Facial Nerve Indentation in Hemifacial Spasm: An Analysis of Factors Contributing to the Formation of and Consequent Effects Associated with Indentation.

BACKGROUND: An indentation, designating a furrowed hole on the facial nerve, has been used in many studies for locating pathophysiology and assessing relevant clinical outcomes after microvascular decompression for hemifacial spasm (HFS). In this study, we sought to elucidate the contributing factors forming indentation on the facial nerve and the consequent effect of having indentation on the clinical course. METHODS: We divided the patients into 2 groups: group A, the patients who had no indentation on the root exit zone of the facial nerve; and group B, the patients who had an indentation. Demographic data, intraoperative findings, and clinical outcomes were analyzed from retrospective review of the medical records. RESULTS: Of the 132 patients, 47.0% had an indentation on the facial nerve. Our statistical analyses showed that the preoperative symptom period, compression location, and compression pattern were associated with the occurrence of the indentation. Also, we showed that HFS reappearance developed more frequently in patients in group B, who needed more time for the resolution of HFS. The final clinical outcome was less influenced by the existence of the indentation, although it was slightly poorer for group B than for group A. CONCLUSIONS: The indentation on the facial nerve was associated with longer duration of symptoms, the presence of compression in the proximal segment of the root exit zone, and loop-type pattern of compression. More patients with indentation experienced the HFS reappearance phenomenon, which lasted longer than in those who had no indentation.

Predicting Arachnoid Membrane Descent in the Chiasmatic Cistern in the Treatment of Pituitary Macroadenoma.

OBJECTIVE: Preoperative prediction of the arachnoid membrane descent in pituitary surgery is useful for achieving gross total removal and avoiding cerebrospinal fluid leakage resulting from tearing of the arachnoid membrane in the chiasmatic cistern. In this study, we analyzed the patterns of arachnoid membrane descent during or after pituitary tumor surgery and identified the factors related to this descent. METHODS: Analysis was restricted to pituitary macroadenomas not extending into the third ventricle or over the internal carotid artery. To minimize confounding factors, patients who underwent revision surgery, those who had a torn arachnoid during operation or small medial diaphragma sellae (DS) opening, and subtotal resections were excluded. We enrolled 41 consecutive patients in this retrospective analysis. The degree of arachnoid descent was categorized using intraoperative videos. Preoperative magnetic resonance findings, including tumor height, suprasellar extension, and variables including DS area and medial opening size, tumor composition, and displacement of the pituitary stalk and gland were evaluated to determine their correlations with arachnoid membrane descent. RESULTS: Arachnoid membrane descent was significantly correlated with DS area and medial opening size. Based on T2-weighted images (T2WI) magnetic resonance (MR) images, tumor composition was significantly associated with arachnoid membrane descent. Other factors were not significantly correlated with arachnoid membrane descent. CONCLUSION: T2WI of tumor composition and preoperative MR imaging of DS area and medial opening provided valuable information regarding arachnoid membrane descent. These parameters may serve as fundamental measures to facilitate complete resection of pituitary macroadenomas.

Correlation between gray matter volume loss followed by aneurysmal subarachnoid hemorrhage and subarachnoid hemorrhage volume.

PURPOSE: Aneurysmal subarachnoid hemorrhage (SAH) can chronically affect cognitive function, and SAH has been suggested to result in regional brain damage. This study aimed to assess regional structural damage according to initial clinical status including SAH volume. METHODS: A total of 63 consecutive patients treated with coil embolization for intracranial aneurysms for more than 6 months were enrolled. Of these, 35 patients had SAH and 28 patients who were treated for unruptured aneurysms served as controls. Volumetric T1-weighted images were acquired with 1 mm isotropic voxel. The SAH volume was measured semi-automatically from the initial brain CT scan. Voxel-based group comparison was conducted to assess regional gray matter volume (GMV) changes. Voxel-based multiple regression was conducted to analyze regional GMV change and SAH volume. The clinical factors (Glasgow Coma Scale (GCS), SAH volume, systolic blood pressure, and serum laboratory findings) associated with regional GMV were also analyzed by using multiple regression. RESULTS: The SAH group had significantly lower GMV in the left hippocampus and higher GMV in the visual cortex than controls (Alphasim-corrected p < 0.05, voxel level of p < 0.001). The GMV of the bilateral hippocampi, thalami, and left medial orbital gyrus was negatively correlated with the initial SAH volume (FDR-corrected p < 0.05). SAH volume and GCS were associated with the hippocampal GMV in multiple regression (p < 0.05). CONCLUSIONS: Chronic regional GMV change after SAH was related to the severity of initial clinical status including SAH volume. This finding supports the pathophysiological hypothesis of SAH-induced microstructural brain injury.

Progressive Multifocal Leukoencephalopathy Diagnosed by Brain Biopsy, not by the DNA Test for JC Virus.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by a lytic infection of oligodendrocytes due to the presence of JC polyomavirus (JCV). The disease occurs mostly in immunocompromised patients and is associated with a high mortality rate. The diagnosis of PML is based on a polymerase chain reaction (PCR) assay for JC viral DNA in cerebrospinal fluid (CSF). However, case reports of the diagnosis of PML established with brain biopsy despite negative JCV CSF PCR analysis when clinical and neuroimaging features are suggestive of PML have been published. A 44-year-old male with a 6-year history of acquired immunodeficiency syndrome developed mental confusion and memory impairment despite 3 months of highly active antiretroviral therapy. Magnetic resonance imaging revealed multiple subcortical white matter lesions in bilateral hemispheres and subcortical nuclei including the thalamus and basal ganglia. JCV DNA was not detected in CSF study, but a brain biopsy showed a high JCV DNA titer. The diagnosis of PML was established with brain biopsy. An early brain biopsy may be important in the diagnosis of PML in patients with clinical manifestations and neuroimaging findings if JCV DNA is undetectable in the CSF PCR.

Management of Pulse Generators in a Breast Cancer Patient with in Situ Subthalamic Nucleus Deep Brain Stimulation.

Although deep brain stimulation (DBS) has been used for > 25 years in the treatment of movement disorders, no report has been published on the management of DBS pulse generators implanted in the anterior chest in patients with breast cancer who require mastectomy, radiotherapy, and future imaging studies.We describe a 62-year-old female patient with advanced Parkinson's disease (PD) who was dependent on bilateral subthalamic nucleus (STN) DBS. She was diagnosed with cancer in her left breast. To avoid difficulties in imaging studies, surgery, and radiotherapy related to the breast cancer, bilateral pulse generators for STN DBS previously implanted in the anterior chest wall were repositioned to the anterior abdominal wall with replacement of long extension cables. During mastectomy and the relocation of the pulse generators, we were not aware of the risks of an open circuit and neuroleptic malignant-like syndrome due to our limited knowledge about how to manage DBS hardware.Coincident breast cancer and the need for STN DBS is underreported. Considering the uncertainties in the management of pulse generators and the incidence of breast cancer, guidelines for handling DBS hardware in the setting of cancer are needed. More careful attention should be paid to performing magnetic resonance imaging in DBS-dependent patients with chronic PD.

Hemifacial Spasm Caused by Vascular Compression in the Cisternal Portion of the Facial Nerve: Report of Two Cases with Review of the Literature.

Although primary hemifacial spasm (HFS) is mostly related to a vascular compression of the facial nerve at its root exit zone (REZ), its occurrence in association with distal, cisternal portion has been repeatedly reported during the last two decades. We report two patients with typical HFS caused by distal neurovascular compression, in which the spasm was successfully treated with microvascular decompression (MVD). Vascular compression of distal, cisternal portion of the facial nerve was identified preoperatively in the magnetic resonance imaging (MRI). It was confirmed again with intraoperative findings of compression of cisternal portion of the facial nerve by the meatal loop of the anterior inferior cerebellar artery (AICA) and absence of any offending vessel in the REZ of the facial nerve. Immediate disappearance of lateral spread response (LSR) after decompression and resolution of spasm after the operation again validated that HFS in the current patients originated from the vascular compression of distal, cisternal portion of the facial nerves. According to our literature review of 64 patients with HFS caused by distal neurovascular compression, distal compression can be classified by pure distal neurovascular compression (31 cases, 48.4%) and double compression (both distal segment and the REZ of the facial nerves, 33 cases [51.6%]) according to the presence or absence of simultaneous offender in the REZ. Eighty-four percent of 64 identified distal offenders were the AICA, especially its meatal and postmeatal segments. Before awareness of distal neurovascular compression causing HFS and sophisticated MRI imaging (before 2000), the rate of reoperation was high (58%). Preoperative MRI and intraoperative monitoring of LSR seems to be an essential element in determination of real offending vessel in MVD caused by distal offender.

Chronic Unilateral Temporo-Occipital Headache Attributed to Unilateral C3 Radiculopathy.

Although C1-C3 upper cervical radiculopathy can cause a headache, most case reports are occipital neuralgia (ON), not headache. Here, we report a unique case of chronic temporo-occipital headache due to C3 radiculopathy. A 62-year-old male presented with a chronic left-sided temporo-occipital headache with duration of 4 years. The headache was aching and pressure like in nature. It had a typical radiating pattern on every occasion. It started in the posterior temporal area above the ear. It then extended to retroauricular area, then suboccipital area, and lateral neck. No hypesthesia, allodynia, or limitation in neck motion was noted. Myelographic computed tomography revealed a left-sided C2/C3 foraminal stenosis. Subsequent foraminotomy and decompression of the left C3 completely alleviated the chronic left-sided temporo-occipital headache. Unilateral C3 radiculopathy can cause chronic temporo-occipital headache besides ON. The present case might be a typical example of "headache attributed to upper cervical radiculopathy" (A11.2.4) rather than cervicogenic headache according to the International Classification of Headache Disorders, 3rd edition (beta version).

Characteristic Signs on T2*-Based Imaging and Their Relationship with Results of Reperfusion Therapy for Acute Ischemic Stroke: A Systematic Review and Evidence to Date.

PURPOSE: Characteristic signs - the susceptibility vessel sign (SVS) and the prominent hypointense vessel sign (PHVS) - on T2*-based magnetic resonance imaging (T2*MRI) can be seen for acute ischemic stroke with large artery occlusion. In this study, we investigated the evidence to support our hypothesis that these findings may help to predict outcomes after reperfusion therapy. MATERIALS AND METHODS: We searched for papers describing SVS and PHVS in patients treated with reperfusion therapy for acute ischemic stroke, and their functional/radiologic outcomes were systematically reviewed. RESULTS: Nine studies on the SVS and six studies on the PHVS were included. The pooled odds ratio (OR) of recanalization after intravenous thrombolysis or mechanical thrombectomy was not significantly different with the presence of SVS (OR, 0.615; 95% confidence interval [CI], 0.335-1.131 and OR, 0.993; 95% CI, 0.629-1.567). The OR of favorable functional outcome after reperfusion therapy in terms of the presence of PHVS varied (0.083 to 1.831) by study. CONCLUSION: Our meta-analysis of the published data showed that a SVS was not a predictive factor for recanalization after reperfusion therapy for acute ischemic stroke. Currently, the data available on T2*MRI are too limited to warrant reperfusion therapy in routine practice. More data are needed from studies with randomized treatment allocation to determine the role of T2*MRI.

A Case of Diffuse Leptomeningeal Glioneuronal Tumor Misdiagnosed as Chronic Tuberculous Meningitis without Brain Biopsy.

Here we report a rare case of diffuse leptomeningeal glioneuronal tumor (DLGNT) in a 62-year-old male patient misdiagnosed as having tuberculous meningitis. Due to its rarity and radiologic findings of leptomeningeal enhancement in the basal cisterns on magnetic resonance imaging (MRI) similar to tuberculous meningitis, DLGNT in this patient was initially diagnosed as communicating hydrocephalus from tuberculous meningitis despite absence of laboratory findings of tuberculosis. The patient's symptoms and signs promptly improved after a ventriculoperitoneal shunting surgery followed by empirical treatment against tuberculosis. Five years later, mental confusion and ataxic gait developed in this patient again despite well-functioning ventriculoperitoneal shunt. Aggravation of leptomeningeal enhancement in the basal cisterns was noted in MRI. An additional course of antituberculosis medication with steroid was started without biopsy of the brain. Laboratory examinations for tuberculosis were negative again. After four months of improvement, his mental confusion, memory impairment, dysphasia, and ataxia gradually worsened. A repeated MRI of the brain showed further aggravation of leptomeningeal enhancement in the basal cisterns. Biopsy of the brain surface and leptomeninges revealed a very rare occurrence of DLGNT. His delayed diagnosis of DLGNT might be due to prevalence of tuberculosis in our country, similarity in MRI finding of prominent leptomeningeal enhancement in the basal cisterns, and extreme rarity of DLGNT in the elderly. DLGLT should be considered in differential diagnosis of medical conditions presenting as communicating hydrocephalus with prominent leptomeningeal enhancement. A timely histologic diagnosis through a leptomeningeal biopsy of the brain and spinal cord in case of unusual leptomeningeal enhancement with uncertain laboratory findings is essential because cytologic examination of the cerebrospinal fluid in DLGNT is known to be negative.

Technical Implications in Revision Surgery for Deep Brain Stimulation (DBS) of the Thalamus for Refractory Epilepsy.

BACKGROUND AND PURPOSE: Implantation of deep brain stimulation (DBS) electrodes in the anterior nucleus of the thalamus (ANT) or the centromedian nucleus (CM), for the treatment of refractory epilepsy, is technically demanding. To enhance the accuracy of electrode placement within the ANT and CM, we analyzed our experience with electrode revision surgery in ANT and CM DBS and investigated the cause of misplacement and verifying methods for accurate placement. METHODS: A retrospective analysis of the medical records of 23 patients who underwent DBS for refractory epilepsy during the period from 2013 to 2016 was performed. RESULTS: Misplacement of the electrode occurred in 1 (25%) of 4 ANT DBS and 2 (14.3%) of 14 patients with CM DBS performed in our institute, and revision surgery was performed in three patients. During this period, we performed three revision surgeries for misplaced electrodes in ANT DBS that were performed at another hospital. Therefore, we performed six revision surgeries (four in ANT, two in CM) for mistargeted DBS electrodes for thalamic DBS. Transventricular lead placement and an anatomical targeting of the ANT was the cause of misplacement in the ANT and intraoperative brain shift was found to be the cause in the CM. For verification of the location of lead placement, magnetic resonance imaging (MRI) was superior to computed tomography and electroencephalography (EEG). CONCLUSIONS: To reduce the rate of electrode misplacement for refractory epilepsy, image-based targeting of the ANT according to individual anatomical variation, and efforts to minimize intraoperative brain shift are essential. To verify the location of the electrode, MRI examination is mandatory in DBS for refractory epilepsy.

Compression of Thoracic Spinal Cord with Decreased Cerebrospinal Fluid Space After Implantation of Paddle Lead Spinal Cord Stimulation at T9: A Three-Dimensional Myelographic Computed Tomography Study.

OBJECTIVES: To investigate the extent of spinal cord compression and cerebrospinal fluid (CSF) space after T9 paddle lead spinal cord stimulation (SCS) using three-dimensional myelographic computed tomography scans. METHODS: Preoperative and postoperative three-dimensional myelographic computed tomography scans were performed in 15 patients with paddle lead SCS at T9 for neuropathic back and leg pain. Four axial levels between each row of the electrodes were selected and the cross-sectional areas of thecal sac and spinal cord, the width of anterior and posterior CSF space, and contact angle of the lead within T9 spinal canal were measured with 12-month pain relief assessment. RESULTS: The cross-sectional areas of thecal sac and spinal cord under each contact of paddle leads decreased significantly (23.89 ± 11.48% and 9.45 ± 4.80%; P < 0.05, respectively). The width of posterior CSF space decreased by 38.65 ± 20.97% and that of anterior CSF space showed a greater reduction by 59.09 ± 18.39% (P < 0.05). We achieved a mean pain relief of 45.49 ± 13.73% at 12-month follow-up and found a significant correlation with percentage reduction in the area of the spinal cord. CONCLUSIONS: Significant reduction in the cross-sectional area of spinal cord and anterior CSF space as well as thecal sac and posterior CSF space resulted in deformation of the spinal cord under paddle leads at T9 within 7 postoperative days. Close approximation to the dorsal column and the mass effect of paddle leads may determine the clinical outcome of paddle lead SCS and also raise safety concerns.

Hemifacial Trigeminal Pain Referred from Occipital Neuralgia Due to Compression of the Greater Occipital Nerve by the Occipital Artery.

Although pathologic vascular contact between the occipital artery and the greater occipital nerve (GON) at the crossing point in the nuchal subcutaneous layer can cause occipital neuralgia, referred hemifacial trigeminal pain from chronic occipital neuralgia owing to this cause is extremely rare.A 61-year-old female patient with left-sided occipital neuralgia for 4 years presented with a new onset of left-sided hemifacial pain. Decompression of the left GON from pathologic contacts with the occipital artery resulted in immediate relief for hemifacial pain and chronic occipital neuralgia. The present case implies that sensitization and hyperactivity of the trigeminocervical complex that receives the convergent input from trigeminal and high cervical occipital nociceptive pathways can be a pathogenic mechanism in referred hemifacial pain from occipital neuralgia. In the present case, a branching tributary of the occipital artery at the crossing point forming a constricting loop above the course of the GON was found to be the cause of entrapment. Because the occipital artery is reported to be consistently located superficial to the GON at the crossing point, a spatial relationship between the occipital artery and the GON rather than a mere adhesion or contact might have pathologic significance in the development of occipital neuralgia.

Intraoperative monitoring of Z-L response (ZLR) and abnormal muscle response (AMR) during microvascular decompression for hemifacial spasm. Interpreting the role of ZLR.

BACKGROUND: Z-L response (ZLR) has been suggested to a new electromyographic (EMG) potential recorded from the facial muscle of patient with hemifacial spasm (HFS) during microvascular decompression (MVD). Although ZLR has been suggested to be useful, experience of ZLR monitoring is limited and its significance during MVD is still unclear. METHODS: To investigate the significance of ZLR, both ZLR and abnormal muscle response (AMR) were simultaneously recorded before and after decompression of root exit zone (REZ) in 20 consecutive patients with HFS. RESULTS: All 19 AMRs elicited before REZ decompression disappeared immediately after decompression of REZ. ZLRs were also observed before decompression of REZ in 19 (95%) of 20 patients. Despite negative conversion of AMR after decompression in 19 patients, ZLR disappeared in only 13 (68.4%) of 19 patients. Among six sustained ZLRs, three showed reduction in the intensity of ZLRs while the other three remained unchanged. There were nine cases featuring attachment of the distal, non-offending portion of offending vessels to the distal course of the facial nerve in addition to attachment to REZ. Negative ZLR conversion and presence of peripheral contact of offending vessels to distal facial nerves showed significant correlations (p < 0.05). ZLR could be elicited by electrical stimulation at non-REZ-offending portion of the offending arterial wall, attached to the distal course of the facial nerve. HFS disappeared immediately in all 20 patients. CONCLUSIONS: Although ZLR might be helpful in cases with multiple offenders, interpretation of ZLR needs caution for non-specific transmission of electric current through vessel wall to facial nerve.

Globus Pallidus Internus Deep Brain Stimulation for Disabling Diabetic Hemiballism/Hemichorea.

Unilateral hemichorea/hemiballism (HH) associated with contralateral neuroimaging abnormalities of the basal ganglia, which is characterized by T1 hyperintensity on magnetic resonance imaging (MRI) and is secondary to diabetic nonketotic hyperglycemia, is a rare and unique complication of poorly controlled diabetes mellitus (DM). Although almost all prior reports have documented rapid resolution of HH within days after normalization of blood glucose levels, medically refractory persistent HH has been noted. The experience of surgical intervention for persistent HH is limited. A 46-year-old, right-handed female patient with type 2 DM presented with refractory diabetic HH on the left side of 6 months' duration despite DM control and neuroleptic medication usage. Image-guided deep brain stimulation (DBS) on the right globus pallidus internus (GPi) was performed. A mechanical micropallidotomy effect was observed and chronic stimulation of GPi was quite effective in symptomatic control of diabetic HH until a 16-month follow-up visit. DBS of the GPi can be an effective treatment for medically refractory diabetic HH.