Anatomical considerations and surgical manipulation of the rhomboid lip in microvascular decompression for hemifacial spasm.

BACKGROUND: In microvascular decompression (MVD) procedures for hemifacial spasm (HFS), surgeons often encounter a rhomboid lip which may obscure the root exit zone (REZ) of the facial nerve. This study aims to explore the anatomical variations of rhomboid lips and their surgical implications to improve safety and effectiveness in MVD surgeries. METHODS: A retrospective analysis was conducted on 111 patients treated for HFS between April 2021 and March 2023. The presence of a rhomboid lip was assessed through operative video records, and its characteristics, dissection methods, and impact on nerve decompression outcomes were further examined. Preoperative magnetic resonance imaging (MRI) scans were reviewed for detectability of the rhomboid lip. RESULTS: Rhomboid lips were identified in 33% of the patients undergoing MVD, with a higher prevalence in females and predominantly on the left side. Two distinct types of rhomboid lips were observed: membranous and cystic variations. The membranous type was noted for its smaller size and position ventral to the choroid plexus. In contrast, the cystic variation was distinguished by its larger size and a thin membrane that envelops the choroid plexus. Preoperative MRI successfully identified rhomboid lips in only 21% of the patients who were later confirmed to have them in the surgical procedures. Surgical approaches primarily involved incisions on the dorsal wall and along the glossopharyngeal nerve root, with only limited need for extensive dissection from lower cranial nerves. Immediate spasm relief was observed in 97% of the patients. One case exhibited a lower cranial nerve deficit accompanied by brainstem infarction, which was caused by the dissection from the lower cranial nerves. CONCLUSIONS: Recognizing the two variations of the rhomboid lip and understanding their anatomical structures are essential for reducing lower cranial nerve injuries and ensuring effective nerve decompression.

[Microsurgical Procedures of Microvascular Decompression for Trigeminal Neuralgia].

Microvascular decompression for trigeminal neuralgia was successfully performed following the secure surgical steps. The most crucial step involves creating a safe operative field in the dural opening. The petrotentorial junction should be identified without cerebellar retraction before proceeding to the deeper areas. Dissecting the petrosal vein and opening the horizontal fissure contributed to the expansion of the operative field. Bleeding often occurs from the dorsal cerebellar bridging vein and junction of the petrosal vein into the superior petrosal sinus. Transposition of the most common offenders, the superior and anterior inferior cerebellar arteries, is effectively achieved by dissecting both the proximal and distal sides of the neurovascular compression site. Teflon should be placed at a sufficient distance to prevent contact with the nerve, which can lead to recurrence. Treating vertebrobasilar artery-related cases is challenging and involves the risk of cranial nerve injuries. Multiple offending vessels are commonly involved. In such cases, it is essential to be aware of the course of the trochlear and abducens nerves during decompression. Applying the most effective and least risky maneuver is necessary for treating cases involving the vertebrobasilar artery.

Potential reasons for failure and recurrence in microvascular decompression for hemifacial spasm.

BACKGROUND: To examine the factors contributing to persistent and recurrent hemifacial spasms (HFS) following a microvascular decompression (MVD) procedure and to suggest technical improvements to prevent such failures. METHODS: A retrospective review was conducted on fifty-two cases of repeat surgery. The extent of the previous craniotomy and the location of neurovascular compression (NVC) were investigated. The operative findings were categorized into two groups: "Missing Compression" and "Teflon Contact". The analysis included long-term outcomes and operative complications after repeat MVD procedures. RESULTS: Missing compression was identified in 29 patients (56%), while Teflon contact was observed in 23 patients (44%). Patients with missing compression were more likely to experience improper craniotomy (66%) compared to those with Teflon contact (48%). Medially located NVC was a frequent finding in both groups, mainly due to compression by the anterior inferior cerebellar artery. In the missing compression group, during the repeat MVD, Teflon sling retraction was utilized in 79% of cases, while in the Teflon contact group, the most common procedure involved removing the Teflon in contact (65%). After the repeat MVD procedure, immediate spasm relief was achieved in 42 patients (81%), with six (12%) experiencing delayed relief. After a median follow-up of 54 months, 96% of patients were free from spasms. Delayed facial palsy, facial weakness, and hearing impairment were more frequently observed in the Teflon contact group. CONCLUSIONS: A proper craniotomy that provides adequate exposure around the REZ is crucial to prevent missing the culprit vessel during the initial MVD procedure. Teflon contact on the REZ should be avoided, as it poses a potential risk of procedure failure and recurrence.

Common trunk anomaly of the anterior and posterior inferior cerebellar artery in hemifacial spasm.

BACKGROUND: The common trunk anomaly of the anterior and posterior inferior cerebellar artery (APC) is a variant artery that causes a hemifacial spasm (HFS). The anatomical characteristics include a large diameter of the trunk and the existence of the bifurcation near the facial nerve root entry zone (REZ). Despite APC being encountered at a constant rate in microvascular decompression (MVD), the anatomical and technical issues of transposing APC have not been entirely focused on yet. METHODS: We reviewed our 68 cases with APC involvement. Patient background, radiological findings, and operative video recordings were reviewed retrospectively. The location of the bifurcation of APC and the distribution of perforators were investigated. Surgical outcomes were assessed in the long term. RESULTS: APC involvement was diagnosed preoperatively in all cases by careful observation with MRI. Three-dimensional images determined the anatomical characteristics of APC and depicted the relationship with the facial nerve. All patients had a bifurcation close to the root entry zone that was required to transpose, including the common trunk and the distal branches, to achieve sufficient decompression. While adequate transposition from the REZ was accomplished in most cases, it was difficult to complete transposition due to short perforators in 6 patients (8.8%), resulting in interposition. Fifty-three patients (77.9%) became spasm free immediately after surgery, 66 patients (97.1%) were after 6 months, and all patients (100%) became spasm free within a year. Spasm-free status was maintained during the follow-up period (4.7 years) in all patients except one in whom facial spasm recurred 2 years after the initial surgery. CONCLUSIONS: Transposing the common trunk with the bifurcation and distal branches contributes to obtaining favorable surgical outcomes in APC-related HFS.

Effect of high-dose delivery on the attachment of meningiomas in Gamma Knife surgery: a retrospective study.

BACKGROUND: Meningiomas have vascular supply from the tumor attachment on the dura mater. Gamma Knife radiosurgery (GKS) is known to have a vascular obliterating effect. This study aims to determine the benefits of high-dose irradiation to the tumor attachment compared to conventional dose planning in the long-term control of tumor growth with GKS. METHODS: Two different dose plannings were retrospectively compared in 75 patients with meningioma treated with GKS as a primary treatment. Forty-three patients were irradiated over 20 Gy to the tumor attachment. The remaining 32 patients were treated with conventional-dose planning. Tumor growth control, reduction of enhancement on the gadolinium-enhanced magnetic resonance imaging (MRI), and neurological status were retrospectively assessed. RESULTS: The maximum dose on the tumor attachment was significantly higher in the high-dose group (23 Gy) than in the conventional group (16 Gy). The tumor margin was irradiated with the median of the 50% isodose line in both groups. The prescription doses resulted in 14 Gy and 12 Gy, respectively. The tumor control rate achieved 91% in both groups during the median follow-up period of 54 months. A decrease of enhancement on follow-up MRI was noted in one patient in each group. Kaplan-Meier analysis revealed no statistical difference in the progression-free survival between the two groups. The number of patients with improved neurological status showed no statistical difference. CONCLUSIONS: No obvious benefit of high-dose irradiation to the tumor attachment and margin was found in tumor control and neurological status in the long term.

Indication for a skull base approach in microvascular decompression for hemifacial spasm.

BACKGROUND: A thorough observation of the root exit zone (REZ) and secure transposition of the offending arteries is crucial for a successful microvascular decompression (MVD) for hemifacial spasm (HFS). Decompression procedures are not always feasible in a narrow operative field through a retrosigmoid approach. In such instances, extending the craniectomy laterally is useful in accomplishing the procedure safely. This study aims to introduce the benefits of a skull base approach in MVD for HFS. METHODS: The skull base approach was performed in twenty-eight patients among 335 consecutive MVDs for HFS. The site of the neurovascular compression (NVC), the size of the flocculus, and the location of the sigmoid sinus are measured factors in the imaging studies. The indication for a skull base approach is evaluated and verified retrospectively in comparison with the conventional retrosigmoid approach. Operative outcomes and long-term results were analyzed retrospectively. RESULTS: The extended retrosigmoid approach was used for 27 patients and the retrolabyrinthine presigmoid approach was used in one patient. The measurement value including the site of NVC, the size of the flocculus, and the location of the sigmoid sinus represents well the indication of the skull base approach, which is significantly different from the conventional retrosigmoid approach. The skull base approach is useful for patients with medially located NVC, a large flocculus, or repeat MVD cases. The long-term result demonstrated favorable outcomes in patients with the skull base approach applied. CONCLUSIONS: Preoperative evaluation for lateral expansion of the craniectomy contributes to a safe and secure MVD.

Location of the abducens nerve stretched by a tortuous vertebrobasilar artery in trigeminal neuralgia.

BACKGROUND: Trigeminal neuralgia (TGN) caused by the vertebrobasilar artery (VBA) is uncommon. The abducens nerve root is frequently dislocated by a tortuous VBA near the trigeminal nerve root. This unusual location of the root is not well known. This study aimed to investigate the location of the stretched abducens nerve root. METHODS: The objective is 26 patients with VBA-related TGN who underwent microvascular decompression (MVD). We retrospectively investigated the course of the abducens nerve root with magnetic resonance imaging (MRI) with three-dimensional (3D) imaging and surgical findings. The displacement of the abducens nerve root on the affected side was compared to the contralateral side. RESULTS: The abducens nerve root was distorted by a tortuous VBA (46.2%) or the anterior inferior cerebellar artery (53.8%). The average length of the cisternal segment was stretched to 23.4 mm versus 12.4 mm on the contralateral side. The peak point of the elevated abducens nerve root was mostly located rostro-medial (65.4%) or caudo-medial (34.6%) to the neurovascular compression site of the trigeminal nerve with a mean distance of 9.1 mm. Contact with the trigeminal nerve root was observed in 7 patients (26.9%). Three-dimensional imaging was consistent with the surgical findings and useful in predicting the location of the abducens nerve root. No abducens nerve palsy was noted in our series. CONCLUSIONS: The abducens nerve root is located near the trigeminal nerve root in VBA-related TGN. Preoperative understanding of the unusual course of the abducens nerve root contributes to avoiding accidental nerve injury during MVD.

Microvascular decompression for trigeminal neuralgia attributable to the vertebrobasilar artery: decompression technique and significance of separation from the nerve root.

BACKGROUND: Separation of the vertebrobasilar artery (VBA) from the trigeminal nerve root in microvascular decompression (MVD) is technically challenging. This study aimed to review the clinical features of VBA involvement in trigeminal neuralgia and evaluate surgical decompression techniques in the long term. METHODS: We retrospectively reviewed the surgical outcomes of 26 patients (4.4%) with VBA involvement in 585 consecutive MVDs for TGN using a Teflon roll for repositioning the VBA. The final operative status of the nerve decompression was categorized into two groups: the separation group and the contact group. Separation of the VBA from the nerve root was completed in 13 patients in the separation group, and slight vascular contact remained in the remaining 13 patients of the contact group. The clinical features of VBA-related TGN were investigated and the operative results were analyzed. RESULTS: Multiple arteries are involved in neurovascular compression (NVC) in most cases. The anterior inferior cerebellar artery was the most common concomitant artery (69%). The site of the NVC varies from the root entry zone to the distal portion of the root. All patients were pain-free immediately after surgery and maintained medication-free status during the follow-up period, except for one patient (3.8%) who had recurrent facial pain 8 years after surgery. Postoperative facial numbness was observed in six patients (23%). Of these, one patient showed improvement within 3 months and the other five patients had persistent facial numbness (19.2%). Other neurological deficits include one dry eye, one diplopia due to trochlear nerve palsy, two decreased hearing (< 50 db), two facial weaknesses, and two cerebellar ataxia. Although most of them were transient, one dry eye, two hearing impairments, and one cerebellar ataxia became persistent deficits. Statistical analyses revealed no difference in surgical efficacy or complications in the long term between the two groups. CONCLUSIONS: Slightly remaining vascular contact does not affect pain relief in the long term. Our study indicated that once the tense trigeminal nerve is loosened, further attempts to mobilize the VBA are not necessary.

Redo surgery for trigeminal neuralgia: reasons for re-exploration and long-term outcomes.

BACKGROUND: To investigate the causes of failure and recurrence after microvascular decompression (MVD) for trigeminal neuralgia (TGN) and to analyze the results of redo surgery. METHODS: Sixty-three cases of redo surgery were retrospectively reviewed. Reasons for re-exploration were categorized into 4 groups based on the operative findings. Patient characteristics, outcomes of re-exploration, and operative complications were analyzed by Kaplan-Meier and logistic regression analyses. RESULTS: Reasons for redo surgery were divided into arterial compression in 13 patients (21%), venous compression in 11 patients (17%), prosthesis-related in 25 patients (40%), and adhesion or negative exploration in 14 patients (22%). Immediate pain relief was obtained in 59 patients (94%) postoperatively with newly developed facial numbness in 17 patients (27%). Of these, 48 patients (76%) maintained pain-free 1 year postoperatively. Overall recurrence was noted in 17 patients (27%) during the median 49-month follow-up period. Most recurrences occurred within 1 year after redo surgery, but the prosthesis-related patients showed a continuous recurrence up to 4 years. Patients having vascular compression showed significantly better pain control than those without vascular contact in Kaplan-Meier analyses (p = 0.0421). No prognostic factor for pain-free 1 year after redo surgery was found. CONCLUSIONS: Redo surgery is effective for patients with remaining vascular compression rather than those without vascular contact. Teflon contact onto the nerve root should be avoided because it is a potential risk for recurrence and causes poor prognosis after redo surgery.

Double collagen matrix grafting for dural closure in microvascular decompression: an alternative use of autologous fascial grafting.

BACKGROUND: Watertight dural closure is a crucial step in preventing postoperative cerebrospinal fluid (CSF) leak and subsequent infection in posterior fossa surgery. The aim of this study is to assess an alternative use of collagen matrix double grafting in microvascular decompression (MVD). METHODS: Dural closure using double collagen matrix grafts was retrospectively compared with autologous fascial grafting in 120 patients who underwent MVD. Double collagen matrix grafting technique, a combination use of inlay and onlay grafting (DuraGen®, Integra Lifesciences, Plainsboro, NJ, USA, $700-800 for an MVD craniotomy size), was applied in 60 patients (the collagen matrix group). In the remaining 60 patients, an autologous fascial graft was sutured in a watertight fashion to the dural defect (the fascia group). Postoperative wound complications, such as CSF leak and infection, were retrospectively compared between the two groups. RESULTS: CSF leaks were observed in 3 patients (5.0%) in the fascia group and in 2 patients (3.3%) in the collagen matrix group. All cases of CSF leakage presented with pseudomeningoceles except one patient who developed an incisional CSF leak. A repair surgery for CSF leak was required in this one patient in the fascia group. Subcutaneous abscesses were noted in 2 patients (3.3%) in the fascia group. There was no patient who developed a subcutaneous abscess in the collagen matrix group. One patient in each group developed aseptic meningitis. Statistical analyses revealed that the collagen matrix group showed non-inferior outcomes to the fascia group in CSF leaks and infectious complications. CONCLUSIONS: Double grafting technique with a combination of inlay and onlay collagen sheets is a safe and secure alternative for watertight dural closure despite a cost limitation.

Bridge technique for hemifacial spasm with vertebral artery involvement.

BACKGROUND: To assess efficacy and safety of a newly developed decompression technique in microvascular decompression for hemifacial spasm (HFS) with vertebral artery (VA) involvement. METHODS: A rigid Teflon (Bard® PTFE Felt Pledget, USA) with the ends placed between the lower pons and the flocculus creates a free space over the root exit zone (REZ) of the facial nerve (bridge technique). The bridge technique and the conventional sling technique for VA-related neurovascular compression were compared retrospectively in 60 patients. Elapsed time for decompression, number of Teflon pieces used during the procedure, and incidences of intraoperative manipulation to the lower cranial nerves were investigated. Postoperative outcomes and complications were retrospectively compared in both techniques. RESULTS: The time from recognition of the REZ to completion of the decompression maneuvers was significantly shorter, and fewer Teflon pieces were required in the bridge technique than in the sling technique. Lower cranial nerve manipulations were performed less in the bridge technique. Although statistical analyses revealed no significant differences in surgical outcomes except spasm-free at postoperative 1 month, the bridge technique is confirmed to provide spasm-free outcomes in the long-term without notable complications. CONCLUSIONS: The bridge technique is a safe and effective decompression method for VA-involved HFS.

A Method for Measuring the Surface Free Energy of Topical Semi-solid Dosage Forms.

Our aim was to determine the surface free energy (SFE) of semi-solid dosage forms (SSDFs) by establishing a reproducible method for measuring the contact angle of liquids to SSDFs. Four SSDFs were used: petrolatum, an oil/water (O/W) and a water/oil (W/O) cream, and an alcohol-based gel. The SSDFs were evenly spread on a glass slide, and the change in contact angle over time was measured by dropping water, glycerol, diiodomethane and n-hexadecane as the test liquids. Depending on the combination of test liquid and SSDF, the contact angle was either constant or decreased in an exponential manner. Contact angles may have decreased in an exponential manner because the reaction between the test liquid and the SSDF altered the interfacial tension between the two phases and changed the surface tension of the test liquid and the SFE of the SSDF. The contact angle of the test liquid to the SSDF could be determined reproducibly using the initial contact angle immediately after dropping the liquid on the SSDF as the contact angle before reaction. Using the obtained contact angles and the Owens-Wendt-Rabel-Kaelble equation, we calculated the SFE and its component for the SSDFs tested and found that the results reflect the physicochemical properties of SSDFs. Furthermore, the work of adhesion (WA) of the SSDF to Yucatan micropig skin was calculated using the SFE for the SSDFs. Interestingly, the WA values for all SSDFs tested were comparable.

Resection of the suprameatal tubercle in microvascular decompression for trigeminal neuralgia.

BACKGROUND: The suprameatal tubercle (SMT) may obscure the neurovascular compression (NVC) in microvascular decompression (MVD) for trigeminal neuralgia (TGN). The aim of this study is to address the necessity of resecting SMT in MVD for TGN. METHODS: We retrospectively analyzed radiological findings of 461 MVDs in patients with TGN, focusing on the relation between SMT and the NVC site. Three-dimensional (3D) images were used for preoperative evaluation. The NVC sites were obscured by SMT in 48 patients (10.4%) via the retrosigmoid approach. This study was conducted to review the management of SMT among these patients. Resection of SMT was performed in 8 patients (resected group) for direct visualization of the NVC site. On the other hand, nerve decompression was achieved without resecting SMT for the rest of the 40 patients (non-resected group). Biographical data, radiological findings, intraoperative findings, and surgical outcomes were retrospectively evaluated. RESULTS: The mean height of SMT obscuring NVC was 5.0 mm (2.8-13.9 mm) above the petrous surface. The NVC was located at a mean of 1.9 mm (0-5.9 mm) from the porous trigeminus. The most common offending vessel was the superior cerebellar artery (SCA, 56.3%), followed by the transverse pontine vein (TPV, 29.2%). In the resected group, the transposing culprit vessels were feasibly performed after direct visualization of the NVC site, whereas in the non-resected group, the SCA was successfully transposed using curved instruments after thorough dissection around the nerve. TPV having contact with the nerve was coagulated and divided. Immediate pain relief was obtained in all patients except one who experienced delayed pain relief 1 month after surgery. Facial numbness at discharge was noted in 9 patients (18.8%); thereafter, numbness diminished over time. Numbness at the final visit was observed in 5 patients (10.4%) at mean of 49 months after MVD. Recurrent pain occurred in 4 patients (8.3%) in total. Statistical analysis showed no significant differences in surgical outcomes between both groups. CONCLUSIONS: Direct visualization of the NVC site by resecting the SMT does not affect surgical outcomes in the immediate and long term. Resecting the SMT is not always necessary to accomplish nerve decompression in most cases by use of suitable instruments and techniques.

[Subarachnoid Hemorrhage of Unknown Origin at Initial Imaging Investigation].

In some patients with spontaneous subarachnoid hemorrhage(SAH), initial imaging investigations may not be able to detect a bleeding source;repeat imaging may be necessary to reveal these lesions. We reviewed a consecutive series of 45 patients with SAH and negative initial digital subtraction angiograms(DSA)during a 15-year period. The aims were to document the frequency and reason for the negative initial investigations, to determine the appropriate modality and timing of repeat examinations, and to investigate the identified bleeding sources. Twenty-eight(62%)patients underwent repeat DSA, 35(78%)underwent magnetic resonance imaging(MRI), and 33(73%)underwent computed tomography angiography(CTA). Nine lesions(5 small aneurysms, 2 craniocervical junction arteriovenous fistulas, 1 arteriovenous malformation, and 1 internal carotid artery dissection)were identified on subsequent DSA after 2-3 weeks. Most aneurysms were identified on an atypical vascular tree. CTA or MRI alone were unable to disclose the culprit lesions. In retrospect, human errors including oversight were the major reasons for the negative initial investigation results. It is, however, difficult to search for a tiny vascular lesion that might be anywhere in the cranium. Repeat DSA is still the gold standard for the inspection of hidden bleeding sources in patients with SAH of unknown origin.

Neurological symptoms in a patient with isolated adrenocorticotropin deficiency: case report and literature review.

BACKGROUND: Isolated adrenocorticotropic hormone (ACTH) deficiency is a pituitary disorder characterized by reduction only in the secretion of ACTH. Although the underlying mechanism remains to be elucidated, numbers of cases with this entity have been increasing. We experienced a case presenting with gait disturbance necessitating differential diagnosis from idiopathic normal pressure hydrocephalus (iNPH). CASE PRESENTATION: A 69-year-old female with a complaint of difficulty walking and suspected to have iNPH at a prior hospital was referred to our department. For the prior three years, she had suffered from a progressive gait disturbance. Magnetic resonance imaging (MRI) revealed global ventricular dilatation. The typical features of the gait in iNPH cases were all identifiable. Neuropsychological dementia scale tests showed deterioration. However, the major feature of a disproportionately enlarged subarachnoid-space on MRI was not obvious. The patient developed progressively worsening fatigue during hospitalization. Her symptoms resembled those of hypothalamic-pituitary tumor patients. Serum ACTH and cortisol levels were low. While corticotrophin releasing hormone stress tests showed no response, other stress tests using thyrotropin releasing hormone, luteinizing hormone releasing hormone, and growth hormone releasing hormone yielded normal responses, indicating a diagnosis of isolated ACTH deficiency. We initiated corticosteroid therapy, and her gait disturbance improved promptly. CONCLUSION: Isolated ACTH deficiency may have major significance to the differential diagnosis of iNPH. Early consideration of this entity is anticipated to facilitate making an early diagnosis.

Ruptured intracranial aneurysm during pregnancy with false-negative computed tomography angiography findings: a case report.

A 34-year-old female was admitted at 34 weeks of gestation with sudden onset of a severe headache accompanied by vomiting. Neurological examination revealed neck rigidity, and computed tomography (CT) of the brain revealed a subarachnoid hemorrhage (SAH). Although the hemorrhage was located primarily in the left Sylvian fissure, computed tomography angiography (CTA) performed immediately after CT did not reveal any obvious vascular abnormalities such as an intracranial aneurysm. An emergency cesarean section was performed, and a healthy infant was delivered. Cerebral digital subtraction angiography (DSA) was performed the day following surgery, which revealed a saccular aneurysm measuring 4.3 mm × 2.4 mm in the left middle cerebral artery. Left craniotomy and clipping of the aneurysm were performed. The clot around the aneurysm was relatively solid. This case report is of significance given that initial CTA was negative for SAH during pregnancy, suggesting the requirement for immediate DSA or another CTA in such cases. There are many previous reports on false-negative CTA findings or disappearance and reappearance of aneurysms in SAH patients, and various biophysical and dynamic parameters are suggested to cause such phenomena. However, there are no reports on similar occurrences during pregnancy. Although the precise cause remains unclear, multiple factors associated with homeostasis during pregnancy were possibly associated with the transient disappearance in this patient.

Intercollicular Approach for Midbrain Cavernous Malformation: 2-Dimensional Operative Video.

Previously reported midbrain cavernous malformations often exhibit lateral expansion, making their excision through the nearest brain surface incision easier.1-5 Nevertheless, excising a midbrain cavernous malformation that lacks lateral extension can be particularly challenging because of limited access.5 The anterior midline approach is typically conducted through the interpeduncular fossa zone.3,5 Still, it restricts surgical maneuverability because of the presence of the posterior communicating artery, the posterior cerebral artery, and the oculomotor nerve. On the other hand, the posterior midline approach through the intercollicular region, although reported in only a single case, lacks technical details and postoperative neurological status.3,5 In this report, we elaborate on the feasibility of surgical manipulations for midline-located midbrain cavernous angiomas through the intercollicular region and discuss the resulting postoperative neurological outcomes.

Abducens Nerve Palsy Due to Neurovascular Compression.

BACKGROUND: Neurovascular compression (NVC) as the cause of abducens nerve palsy is an infrequent event. Only a small number of cases have been reported in the literature, and the efficacy of microvascular decompression (MVD) for abducens nerve palsy remains unclear. METHODS: We reviewed previously reported cases of abducens nerve palsy caused by NVC and added our own cases. We analyzed the clinical characteristics of vascular compression abducens nerve palsy and assessed the indication for MVD. RESULTS: Twenty-two patients with isolated abducens nerve palsy due to vascular compression were confirmed in total, consisting of 20 patients (19 publications) from the literature search and 2 cases from our experienced cases. All patients had no possible causes for isolated abducens nerve palsy except the NVC on the nerve root. Unlike the sudden onset in the typical abducens nerve palsy, all patients demonstrated gradual development of the symptom in NVC-related abducens palsy. Careful observation was the most common strategy in most patients; however, no noticeable improvement was reported in the conservative treatment. Surgical intervention was performed in 6 patients after observation for several months and showed favorable outcomes in all cases. CONCLUSIONS: Vascular compression could be a potential cause of abducens nerve palsy. Gradual onset or episodic symptom of abducens palsy with a definitive radiological finding of vascular compression deserves considering MVD for abducens nerve palsy.

Bridge technique for hemifacial spasm with vertebral artery involvement: 2-Dimensional operative video.

Microvascular decompression for hemifacial spasm (HFS) associated with the vertebral artery (VA) is more challenging than that for small arteries. Atherosclerotic VA and tortuous VA are associated with a low success rate and high incidences of complications. Artery relocation employing a Teflon sling is helpful for small arteries. However, a different decompression technique should be considered in VA-related HFS due to the stiffness of the offending artery. With our simple decompression technique providing a secure transposition that can be performed even in the narrow cistern, a rigid Teflon bar is inserted to hold up all offending vessels between the pontine surface and the cerebellar flocculus (the bridge technique). This simple technique easily creates a free space over the root entry zone (REZ), reduces surgical manipulation compared to conventional artery relocation with a Teflon sling, and provides more secure nerve decompression than inserting Teflon pledgets on the REZ. The critical factors for successfully performing the bridge technique are using a rigid Teflon bar that can hold the rebound force of the VA and a length appropriate to generate a free space over the REZ between the pons and the cerebellar flocculus. In this video, we demonstrate our bridge technique for VA-related HFS and discuss the advantages and disadvantages of this novel approach.

Lumboperitoneal Shunt Surgery under Spinal Anesthesia on Idiopathic Normal Pressure Hydrocephalus Patients.

Since the publication of guidelines for managing idiopathic normal pressure hydrocephalus (iNPH) in 2004, an increasing number of patients with iNPH have been undergoing shunt surgery in Japan. However, shunt surgeries for iNPH can be challenging because the procedures are performed on elderly patients. General anesthesia-related risks, such as postoperative pneumonia or delirium, are higher in the elderly. To decrease these risks, we applied spinal anesthesia on a lumboperitoneal shunt (LPS). Herein, we analyzed our methods focusing on the postoperative outcomes. We retrospectively analyzed 79 patients who underwent LPS at our institution with more than one year of follow-up. The patients were divided into two groups based on the anesthetic approach, that is, 1) general anesthesia and 2) spinal anesthesia, and were examined in terms of postoperative complications, delirium, and postoperative hospital stay. In the general anesthesia group, two patients had respiratory complications after the surgery. The postoperative delirium score using the intensive care delirium screening checklist (ICDSC) was 0 (2) (median [interquartile range]), and the length of postoperative hospital stay was 11 (4) days. In the spinal anesthesia group, no patients had respiratory complications. The postoperative mean ICDSC was 0 (1), and the length of postoperative hospital stay was 10 (3) days. Although there was no significant difference regarding postoperative delirium existed, LPS under spinal anesthesia decreased respiratory complications and significantly shortened the postoperative hospital stay. LPS under spinal anesthesia could be an alternative to general anesthesia in elderly patients with iNPH and possibly lessen the general anesthesia-related risks.