Role of Microelectrode Recording in Deep Brain Stimulation of the Pedunculopontine Nucleus: A Physiological Study of Two Cases.

BACKGROUND: Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) has been reported to improve gait disturbances in Parkinson's disease (PD); however, there are controversies on the radiological and electrophysiological techniques for intraoperative and postoperative confirmation of the target and determination of optimal stimulation parameters. OBJECTIVES: We investigated the correlation between the location of the estimated PPN (ePPN) and neuronal activity collected during intraoperative electrophysiological mapping to evaluate the role of microelectrode recording (MER) in identifying the effective stimulation site in two PD patients. MATERIALS AND METHODS: Bilateral PPN DBS was performed in two patients who had suffered from levodopa refractory gait disturbance. They had been implanted previously with DBS in the internal globus pallidus and the subthalamic nucleus, respectively. The PPN was determined on MRI and identified by intraoperative MER. Neuronal activity recorded was analyzed for mean discharge rate, bursting, and oscillatory activity. The effects were assessed by clinical ratings for motor signs before and after surgery. RESULTS: The PPN location was detected by MER. Groups of neurons characterized by tonic discharges were found 9-10 mm below the thalamus. The mean discharge rate in the ePPN was 19.1 ± 15.1 Hz, and 33% of the neurons of the ePPN responded with increased discharge rate during passive manipulation of the limbs and orofacial structures. PPN DBS with bipolar stimulation at a frequency range 10-30 Hz improved gait disturbances in both patients. Although PPN DBS provided therapeutic effects post-surgery in both cases, the effects waned after a year in case 1 and three years in case 2. CONCLUSIONS: Estimation of stimulation site within the PPN is possible by combining physiological guidance using MER and MRI findings. The PPN is a potential target for gait disturbances, although the efficacy of PPN DBS may depend on the location of the electrode and the stimulation parameters.

[Anterior Cervical Discectomy and Fusion:Safe Surgical Operation Based on Detailed Anatomical Knowledge].

Anterior cervical discectomy and fusion(ACDF)was developed by R.B. Cloward in the 1950s and it has spread over the world for the treatment of the spinal degenerative disorders. It is considered to be the most effective treatment for patients with anterior compression of the spinal cord. Because most of the surgical complications reportedly occur while approaching the vertebral column through the subcutaneous tissues, precise knowledge of the topographic anatomy of the neck is crucial for effective and safe surgery. In this paper, we describe the appropriate surgical maneuvers in each surgical step, based on anatomical knowledge, for avoiding surgery-related complications. We would like to emphasize that anatomical features differ with individual patients; therefore, careful preoperative evaluation is very important. Surgical strategy, based on adequate preoperative evaluation, will lead to good postoperative results.

Long-Term Suppression of Disabling Tremor by Thalamic Stimulation in a Patient with Spinocerebellar Ataxia Type 2.

The beneficial effect of thalamic deep brain stimulation (DBS) on action tremor has been reported in a few cases of spinocerebellar ataxia (SCA); however, several factors should be taken into account regarding the indication for DBS in advanced cases. We performed DBS of the ventral intermediate nucleus (Vim) of the thalamus for treatment of coarse action tremor in a patient with SCA2 (spinocerebellar ataxia type 2) in the wheelchair-bound stage. Although improvement of the tremor of the proximal part was incomplete, the patient regained substantial parts of daily functioning. The effect lasted for more than 6 years, and the suppression of tremor significantly contributed to maintaining the level of the patient's expression into the bedridden stage. Vim DBS can be a treatment option for tremor in SCA patients, even in the advanced stage, as long as the tremor is depriving the patient of behavioral expression. As residual proximal tremor may hamper functional recovery, DBS of other targets or multi-targets should be further explored to attain a better outcome.

Clinico-Radiological Characteristics and Pathological Diagnosis of Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage.

OBJECTIVE: We aim to clarify the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage and to investigate the efficacy of pathological diagnosis using biopsy specimens. METHOD: We retrospectively reviewed 253 consecutive patients with cortico-subcortical hemorrhage who had been admitted to Aizawa Hospital between January 2006 and July 2013. We had performed craniotomy and hematoma evacuation in 48 patients, as well as biopsy of the evacuated hematoma, cerebral parenchyma adjacent to the hematoma, or both, and they were classified according to the histological results (positive or negative for vascular amyloid deposition) and to the Boston criteria. We compared the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage. We also investigated the detection rate of cerebral amyloid angiopathy with respect to the origins of the specimens. RESULTS: Pathological examination revealed that 22 subjects were positive for vascular amyloid. The number of the cerebral microbleeds located in the deep or infratentorial region was significantly larger in the negative group than in the positive group (P <.05). There was no significant difference in the distribution of lobar cerebral microbleeds and in the prevalence of hypertension. In the probable cerebral amyloid angiopathy-related intracerebral hemorrhage patients, the probability of having vascular amyloid detected by biopsy of both hematoma and parenchyma was 100%. Rebleeding in the postoperative periods was observed in 2 cases (9.1%) of the positive group. CONCLUSIONS: Our results demonstrate the importance and safety of biopsy simultaneously performed with hematoma evacuation. Deep or infratentorial microbleeds are less correlated with cerebral amyloid angiopathy-related intracerebral hemorrhage than with noncerebral amyloid angiopathy-related intracerebral hemorrhage.

Transorbital penetrating head injury by a wooden chopstick in the cavernous sinus: a case report and literature review.

Penetrating head injury is a relatively rare condition associated with high morbidity and mortality. Although the immediate treatment of penetrating head injury is needed, surgical strategies are varied based on the trajectory of the penetrating objects in the cranium. We present a case of 24-year-old man who sustained a transorbital penetrating injury caused by a wooden chopstick. Neuroimages revealed a linear lesion extending from the left intraorbital segment to the cavernous sinus passing through the superior orbital fissure. The foreign body was successfully removed via the transcranial approach without complications. A careful management based on the perioperative images and correct diagnosis is necessary to avoid unfavorable complications. Four cases of transorbital penetrating injuries have been previously reported, in which the foreign body penetrated through the superior orbital fissure and lodged in the cavernous sinus. The frontotemporal craniotomy with extradural approach can be a useful option to remove foreign bodies around the cavernous sinus regions.

A Case of Intraosseous Petrous Bone Arteriovenous Fistula Complicated by Transient Worsening of Ipsilateral Hearing Following Transvenous Coil Embolization.

Objective: We report a rare case of intraosseous arteriovenous fistula (AVF) in the petrous bone occluded by transvenous coil embolization, complicated by transient hearing loss postoperatively. Case Presentation: A 55-year-old female patient underwent medical examination for vertigo and headache. CT showed an osteolytic lesion in the right petrous bone. CTA and DSA revealed an AVF that had caused bone erosion. We performed transvenous coil embolization to obtain complete occlusion of the fistula. Vertigo disappeared soon after the procedure, but hearing loss in the right side worsened to near deafness by that night. We started steroid pulse therapy and heparinization. The hearing gradually recovered to the preoperative level in 10 days. Conclusion: It is important to pay attention to possible hearing loss in cases of transvenous coil embolization for intraosseous AVF in the petrous bone.

Ruptured anterior paraclinoid aneurysms.

The purpose of this study was to evaluate cases of subarachnoid hemorrhage (SAH) from ruptured anterior (dorsal) paraclinoid aneurysms. Anterior paraclinoid aneurysms are defined as aneurysms arising from the anterolateral wall of the proximal internal carotid artery without any relationship to an arterial branch. Between 1991 and 2008, a total of 159 patients with 169 paraclinoid aneurysms were treated at the Shinshu University Hospital and its affiliated hospitals. A retrospective analysis was carried out using charts, operation records, operation videos, and neuroimagings. Twenty six patients had anterior paraclinoid aneurysm. Six patients presented with SAH. Three aneurysms were saccular and the others were blister-like aneurysms based on operative findings. Neck laceration or premature rupture frequently happened during the clipping surgery even though the aneurysm was saccular type. The treatment of a ruptured anterior paraclinoid aneurysm is quite difficult. Trapping and bypass would be recommended for such fragile aneurysms.

Staged radiosurgery alone versus postoperative cavity radiosurgery for patients with midsize-to-large brain metastases: a propensity score matching analysis.

OBJECTIVE: The authors investigated and compared the results of staged stereotactic radiosurgery (S-SRS) alone and those of postoperative cavity SRS (C-SRS) for patients with midsize-to-large brain metastases (BMs). METHODS: Patients with BMs who had undergone S-SRS or C-SRS during the period from 2010 to 2020 were retrospectively identified from an institutional database. The two treatment groups were generated by propensity score matching (PSM; match ratio 2:1) based on 13 potential prognostic covariates: sex, age, Karnofsky Performance Status, type of primary cancer, timing of BM diagnosis, extracranial disease status, driver mutations, molecular target therapy, neurological symptoms, number of BMs, location of BMs treated with S-SRS or C-SRS, maximal tumor or cavity volume, and cumulative intracranial tumor volume. Patient survival and control of intracranial disease were compared between the S-SRS and C-SRS groups using time-dependent analyses taking into account competing events. RESULTS: In total, 110 patients in the S-SRS group and 62 in the C-SRS group were selected by PSM. In the S-SRS group, the median interval between the two radiosurgical sessions was 21 days, and the median total prescription dose was 28 Gy at 50%. In the C-SRS group, the median time from surgery to C-SRS was 16 days, and the median prescription dose delivered to the surgical cavity was 15 Gy at 55%. At the time point of data set fixation, 129 patients had died, 43 were alive, and none had been lost to follow-up. The 2-year survival rates for the S-SRS and C-SRS groups after the initial intervention were 33% and 37% and the median survival times were 14.8 and 17.5 months, respectively (p = 0.33). The 2-year cumulative neurological mortality rates were 11% and 9%, respectively (p = 0.65). The 2-year local failure rates were 32% and 12% (p = 0.036) and the 2-year distant recurrence rates were 55% and 58%, respectively (p = 0.53). The 2-year leptomeningeal disease development rates were 9% and 25%, respectively (p = 0.007). CONCLUSIONS: The present study revealed no significant difference in overall survival or cumulative neurological mortality between the S-SRS and C-SRS groups. The local control failure rate was significantly higher in the S-SRS group, whereas the incidence of leptomeningeal disease development was significantly higher in the C-SRS group.

A Case of Dural Arteriovenous Fistula in the Falx with Prominent Falcine Venous Plexus.

Objective: The falx cerebri is known to have venous plexuses. Although some cases of dural arteriovenous fistula (DAVF) associated with falcine sinus have been reported, DAVF in the falx with prominent falcine venous plexus has not previously been reported. Case Presentation: A 59-year-old male was hospitalized with head trauma. MRI incidentally showed a possible occipital DAVF. CTA and DSA revealed a DAVF in the flax with prominent falcine venous plexus. We performed a selective transarterial embolization with glue and particle, obtaining a complete occlusion of the fistula. Conclusion: We report a rare case of DAVF in the flax with prominent falcine venous plexus that was successfully treated by a transarterial embolization.

Rare sphenoid ridge intracranial mature teratoma in an adult female.

Intracranially located teratomas usually involve midline brain structures. However, they rarely occur in adults. A 26-year-old woman presented with a growing intracranial mass lesion in the left sphenoid ridge without neurological deficits. Magnetic resonance imaging revealed homogenous hyperintensities without contrast enhancement. The patient underwent gross total excision of the soft, yellowish sphenoid ridge tumor with no cystic component. The surgery was uneventful, with no intraoperative complications. Histological analysis revealed a mature teratoma. She attended regular outpatient neuroradiology follow-up appointments. The present case is an unusual example of a mature teratoma with regard to location, neuroimaging appearance, macroscopic intraoperative findings, histological tumor subtype, and patient age and sex.

Relationship between the ophthalmic artery and the dural ring of the internal carotid artery. Clinical article.

OBJECT: The ophthalmic artery (OphA) usually arises from the intradural internal carotid artery (ICA), and the extradural origin has also been known. However, the interdural origin is extremely rare. The purpose of this paper was to clarify the origin of the OphA in patients with a paraclinoid aneurysm in the ICA based on intraoperative findings. METHODS: The authors retrospectively examined 156 patients who underwent direct surgical treatment for 166 paraclinoid aneurysms during a 17-year period. Based on intraoperative findings, 119 ophthalmic arteries were analyzed with respect to their origins. RESULTS: The OphA originated from the intradural ICA on 102 sides (85.7%), extradural on 9 (7.6%), and interdural on 8 (6.7%). Although the extradural origin might be recognized preoperatively, it was difficult to distinguish the interdural origin of the OphA from the intradural one. CONCLUSIONS: The incidence of the interdural origin was 6.7% and was not as rare as the authors expected. Neurosurgeons should know the possible existence of the interdural origin of the OphA to section the medial side of the dural ring.

Accurate Detection of Tumor Infiltration by 11C-Methionine Positron Emission Tomography in a Patient with Central Nervous System Intravascular Lymphoma: A Case Report.

Intravascular lymphoma (IVL) is a rare and clinically devastating subtype of extranodal diffuse large B-cell lymphoma with a distinct presentation. Diagnostic difficulty derives from marked variability in clinical presentations and nonspecific laboratory and radiological findings, especially when central nervous system (CNS) symptoms are the only manifestation. Establishing the diagnosis premortem thus remains a major challenge. We describe a 70-year-old male with CNS IVL. He presented with acute onset of neurocognitive impairments. Diffusion-weighted magnetic resonance imaging (MRI) showed multiple high-intensity areas suggesting occlusive cerebrovascular disease due to emboli, but extensive investigations detected no embolic sources. Intracranial neoplasm was included in a differential diagnosis based on elevated serum lactate dehydrogenase and interleukin 2 receptor levels. Gadolinium-enhanced MRI or 18-fluorodeoxyglucose positron emission tomography (PET) failed to demonstrate specific findings leading to a definite diagnosis, while 11C-methionine PET (MET-PET) distinctively demonstrated an area of focally increased MET uptake in the frontal cortex, suggesting the extent of tumor infiltration. Stereotactic biopsy was conducted under MET-PET imaging guidance and immunohistological examinations confirmed the proliferation and aggregation of CD20-positive lymphoma cells within the lumina of small blood vessels. The findings of the present case first suggest that MET-PET may provide important information on the diagnosis of CNS IVL and on the selection of the optimal site for brain biopsy. Further investigation is necessary to clarify whether positive findings on MET-PET are truly specific and pathognomonic for CNS IVL.

Neuronal activity and outcomes from thalamic surgery for spinocerebellar ataxia.

Objectives: We investigated the effects of deep brain stimulation (DBS) or lesions of the ventral intermediate nucleus (Vim) of the thalamus for spinocerebellar ataxia (SCA) and examined the pathophysiological role of neuronal activity of the Vim underlying ataxia. Methods: Five patients with SCA with cortical atrophy (ages 60-69 years; 2 sporadic and three familial SCA) and five patients with essential tremor (ET) (ages 57-71 years) were treated with Vim surgery. Intraoperatively, we recorded neuronal activity from single neurons in the Vim thalamus while patients were at rest and compared the physiological properties of those neurons between patients with SCA and those with ET. Results: Postsurgery mean scores for the Fahn-Tolosa-Marin Tremor Scale were improved from 78 to 44 in SCA patients and from 54 to 21 in ET patients. Stronger stimulation was necessary to optimize outcomes in SCA as compared to ET patients. We analyzed 68 Vim neurons in SCA and 60 Vim neurons in ET. Mean discharge rates, burst characteristics, and oscillatory activity were similar for both patient groups, however, we observed that the ratio of cells responding to passive manipulation was significantly smaller (P = 0.0001) in SCA (22%) than in ET (71%). Interpretation: Thalamic surgery led to a significant improvement in tremor in SCA patients. One potential mechanism underlying ataxia in SCA may be disruption of cerebellar sensory feedback, which modulates motor commands in the cerebello-thalamo-cortical network.

Inter-capsular resection of cervical vagus nerve schwannoma.

Cervical vagus nerve schwannoma is rare and its surgical procedure is controversial. The tumor is in general benign and slowly growing without causing symptoms, and therefore it should be advised to remove the tumor while preserving neural function. We operated on two patients with cervical vagus nerve schwannoma with the inter-capsular resection technique proposed by Hashimoto et al. without causing neurological deficits. It is the first time that the plane between the tumor-complex capsule layer (epineurium and perineurium) and true tumor capsule layer was histopathologically proved in this paper. The true tumor capsule layer contained no normal neural fibers, tumor tissues and neural sheath. The inter-capsular resection technique is a safe and reliable method for removing cervical vagus nerve schwannoma.

Atlantoaxial dislocation associated with a mass in the extradural craniovertebral junction unrelated to rheumatoid arthritis. Case report.

A 61-year-old woman without rheumatoid arthritis (RA) was admitted with atlantoaxial dislocation (AAD) and a retroodontoid mass at the craniovertebral junction manifesting as a 1-year history of numbness and mild weakness of the right upper extremity. Computed tomography and magnetic resonance (MR) imaging showed AAD and a mass at the craniovertebral junction. She had no past history of RA or trauma in the head and neck. She underwent surgery to obtain the histological diagnosis of the mass and to improve AAD-induced instability. The lesion was approached through the right transcondylar fossa approach with C-1 laminectomy. Intraoperative pathological examination showed cicatrizing collagen fibers and no obvious tumor cells. After partial removal of the lesion, the AAD was fixed with the posterior approach. The symptoms subsided soon after surgery and the mass decreased on MR images taken 3 months after surgery. If a pseudotumor is suspected based on the preoperative radiological investigation in a non-RA patient with AAD and the symptoms are not progressive, stabilization can be expected to induce spontaneous regression without urgent direct excision of the mass.

Gliosarcoma in the Cerebellopontine Angle with Rapid Tumor Growth and Intratumoral Hemorrhage.

BACKGROUND: Gliosarcoma is a relatively rare and bimorphous brain tumor, predominantly located in the brain lobe. Here, we report a rare case of gliosarcoma presenting radiologically in the cerebellopontine angle (CPA) region. CASE DESCRIPTION: The patient was a 71-year-old woman with progressive tinnitus. A series of image examinations showed a rapidly growing CPA tumor, which enlarged from nonexistent to 4 cm in diameter with extension to the internal auditory canal in a short period of 6 months. The patient was operated on in emergency because of intratumoral hemorrhage and rapidly deteriorating neurologic symptoms. Under the diagnosis of gliosarcoma confirmed by pathologic examination, chemotherapy and radiotherapy were conducted after partial resection. The patient recovered uneventfully and the residual tumor disappeared nearly completely on the image taken 6 months later. CONCLUSIONS: Although rare, gliosarcoma should be considered in the differential diagnosis of CPA tumors, especially if it is associated with rapid tumor growth or intratumoral hemorrhage.

Ruptured distal middle cerebral artery aneurysm.

OBJECT: Ruptured distal middle cerebral artery (MCA) aneurysms are uncommon, and their clinical and radiological features are poorly understood. To clarify characteristics of these lesions, the authors undertook a retrospective analysis of nine patients with ruptured distal MCA aneurysms. METHODS: The medical records of patients who underwent surgical repair of ruptured intracranial aneurysms between 1988 and 2002 at Shinshu University Hospital and its affiliated hospitals were retrospectively evaluated. The authors found only nine patients with a ruptured distal MCA aneurysm, and their clinical, neuroimaging, and intraoperative findings were evaluated. CONCLUSIONS: This study of nine patients with distal MCA aneurysms is the largest series to date. Eight lesions were saccular aneurysms that were clipped and the remaining one was a mycotic aneurysm that was trapped. Eight of the nine patients suffered cerebral hematomas with subarachnoid hemorrhage. All patients had good outcomes after obliteration of their aneurysm, although their preoperative condition was not good.

[The efficacy of prophylactic administration of SBT/ABPC for postoperative infection in neurosurgical operations].

We investigated prospectively the efficacy of sulbactam sodium/ampicillin sodium (SBT/ABPC), which is a combination drug of ampicillin and beta-lactamase inhibitor, as a preventive drug against postoperative infection in the field of neurological surgery. One hundred and six patients were given SBT/ABPC as follows: Before anesthetic induction at surgery, 1.5 g of SBT/ABPC was administrated by intravenous drip infusion, and further doses were continued at 12-hour intervals for 5 to 7 days. We assessed postoperative infection, type of surgery, duration of operation, and amount of hemorrhage. Search for related side effects and bacteriological examinations of the nasal cavity and throat before and after treatment were performed. The result was that postoperative infection was found in none of the patients. Adverse reactions due to SBT/ABPC such as apparent skin symptoms or gastrointestinal symptoms were not observed. Considering infections highly resistant to MRSA, SBT/ABPC would be effective to prevent postoperative infection in neurosurgical operations and could be used safely.

The concept and feasibility of EXPERT: intelligent armrest using robotics technology.

BACKGROUND: Continuous precise motions are required in microneurosurgery to provide high-quality surgical results. Stabilizing the surgeon's arm and reducing fatigue during surgery are expected to improve the precision of microsurgical procedures. We have developed an intelligent armrest, EXPERT, that follows the surgeon's hand and fixes at an adequate position automatically using robotics technology. OBJECTIVE: To understand the feasibility of EXPERT by using the system in laboratory experiments and clinical situations. METHODS: EXPERT has an arm holder and acts as a passive controlled robot with 5 degrees of freedom. The system has 3 modes: transfer, arm-holding, and arm-free mode, which are selected automatically. In the transfer mode, the arm holder follows the surgeon's arm. In the arm-holding mode, EXPERT supports the surgeon's arm weight by fixing the arm holder. The surgeon can move his/her arm away from the arm holder in the arm-free mode. The surgeon can change the position of armrest while looking through the microscope and can continue the microsurgical procedure while holding surgical instruments. Since 2010, EXPERT has been applied in 13 surgeries. RESULTS: The EXPERT system decreased surgeon fatigue and reduced difficulty in performing surgical procedures. The EXPERT system markedly reduced surgeon hand tremor. There were no complications related to the use of this system. CONCLUSION: EXPERT is a useful tool for holding the surgeon's arm comfortably and following the surgeon's arm automatically.