Toshihiro Ogiwara

Anatomical study of the trigeminal and facial cranial nerves with the aid of 3.0-tesla magnetic resonance imaging.

OBJECT Neuroimages often reveal that the trigeminal or facial nerve comes in contact with vessels but does not produce symptoms of trigeminal neuralgia (TN) or hemifacial spasm (HFS). The authors conducted this study to determine how often the trigeminal and facial nerves came in contact with vessels in individuals not suffering from TN or HFS. They also investigated the correlation between aging and the anatomical measurements of the trigeminal and facial nerves. METHODS Between November 2005 and August 2006, 220 nerves in 110 individuals (60 women and 50 men; mean age 55.1 years, range 19-85 years) who had undergone brain magnetic resonance (MR) imaging for other reasons were studied. The lengths, angles, ratio, and contact points were measured in each individual. A correlation between each parameter and age was statistically analyzed. RESULTS The mean (+/- standard deviation) length of the trigeminal nerve was 9.66 +/- 1.71 mm, the mean distance between the bilateral trigeminal nerves was 31.97 +/- 1.82 mm, and the mean angle between the trigeminal nerve and the midline was 9.71 +/- 5.83 degrees . The trigeminal nerve was significantly longer in older patients. Of 220 trigeminal nerves, 108 (49.0%; 51 women and 57 men) came in contact with vasculature. There was 1 contact point in 99 nerves (45%) and 2 contact points in 9 nerves (4.1%). Contact without deviation of the nerve was seen in 91 individuals (43 women and 48 men), and mild deviation was noted in 17 individuals (8 women and 9 men). There was no moderate or severe deviation in any individual in this series. The mean length of the facial nerve was 29.78 +/- 2.31 mm, the mean distance between the bilateral facial nerves was 28.65 +/- 2.22 mm, the angle between the nerve and midline was 69.68 +/- 5.84 degrees , and the vertical ratio at the porus acusticus was 0.467 +/- 0.169. Of all facial nerves, 173 (78.6%; 101 in women and 72 in men) came in contact with some vasculature. Contact without deviation was seen on 64 sides (in 37 women and 27 men), mild deviation on 98 sides (in 57 women and 41 men), and moderate deviation on 11 sides (in 7 women and 4 men). There was no severe deviation of the facial nerve in this series. The proximal length of the facial nerve, interval, angle, and ratio against the age were significantly shorter or smaller in the older individuals. CONCLUSIONS The findings in asymptomatic individuals in this study will help in deciding which findings observed on MR images may cause symptoms. In addition, the authors describe the variations of normal anatomy in older individuals. Knowledge of the normal anatomy helps to hone the diagnostic practices for microvascular decompression, which may increase the feasible results on such surgery.

Emergency revascularization for acute main-trunk occlusion in the anterior circulation

We report the surgical results in patients with acute cerebral main-trunk occlusion in the anterior circulation. Between April 2004 and March 2005, 26 patients were surgically treated within 24h after the onset. The occlusion occurred in the internal carotid artery in 10 patients, in the middle cerebral artery in 15, and in the anterior cerebral artery in 1. We investigated the clinical characteristics and surgical treatment and evaluated the outcome using the modified Rankin Scale (mRS). Nine patients underwent anastomosis, 14 had an embolectomy, and 3 had a carotid endarterectomy. In all the patients, revascularization was achieved, and neurological improvement was obtained. At 6months after the onset, eight (30.8%) patients showed a good recovery (defined as grade 1 on the mRS), seven (26.9%) were rated as grade 2, eight (30.8%) were grade 3, and three (11.5%) were grade 4. Manual muscle test on admission was significantly different between the good outcome and the poor outcome groups at 6months after onset. None of the patients experienced any complications related to the surgery. Early surgical revascularization can be an effective and safe treatment modality in appropriately selected patients with acute cerebral main-trunk occlusion in the anterior circulation.

Urgent open embolectomy for cardioembolic cervical internal carotid artery occlusion

Acute ischemic stroke attributable to cervical internal carotid artery (ICA) occlusion is frequently associated with severe disability or death and is usually caused by atherosclerosis. By contrast, the cardioembolic cervical ICA occlusion is rare, and feasibility of urgent recanalization remains unclear. We present the first study in the literature that focuses on urgent open embolectomy for the treatment of cardioembolic cervical ICA occlusion. A retrospective review of the charts for patients undergoing open embolectomy was performed. Between April 2006 and September 2007, 640 consecutive patients with acute ischemic stroke were treated. Of them, three patients (0.47%) with the acute complete cardioembolic cervical ICA occlusion underwent urgent open embolectomy. All patients presented with profound neurological deficits and atrial fibrillation. The urgent open embolectomy achieved complete recanalization in all patients without any complications. All emboli in three patients were very large and fibrinous in histological findings. Two of three patients showed rapid improvement in neurological functions after surgical treatments. The cardioembolic occlusion of the cervical ICA is rare, but its possibility should be considered in patients with acute ischemic stroke suffering profound neurological deficits and atrial fibrillation. Urgent open embolectomy may be a treatment option to obtain successful recanalization for cardioembolic cervical ICA occlusion and is recommended because it is technically easier and similar to carotid endarterectomy.

Primary Malignant Lymphoma of the Trigeminal Nerve: Case Report and Literature Review

BACKGROUND Primary lymphomas of the cranial nerves are extremely rare except for optic nerve lymphoma, and it is difficult to make a correct diagnosis in the initial stage. Here, we report a case of primary malignant lymphoma of the left trigeminal nerve that presented as trigeminal nerve disorder. CASE DESCRIPTION A 47-year-old man presented with aggravating left facial pain and hypesthesia within all three divisions of the trigeminal nerve. Magnetic resonance imaging (MRI) revealed a swollen left trigeminal nerve with gadolinium homogenous enhancement. An open biopsy had to be taken from two different locations of the tumor via the lateral suboccipital approach followed by subtemporal approach because adequate specimen volume was not obtained for definitive diagnosis at the first surgery. Histopathological examinations with flow cytometric analysis revealed diffuse large B cell lymphoma. Chemotherapy followed by whole-brain radiation therapy was effective. No recurrence was observed during a 15-month follow-up period. CONCLUSIONS This is a rare clinical presentation of malignant lymphoma of the trigeminal nerve. It is difficult to establish a correct diagnosis of trigeminal nerve lesions during the initial stages without biopsy. Therefore it is important that a sufficient specimen should be taken for biopsy without hesitation in order to diagnose and treat rapidly. The most suitable operative approach must be selected in trigeminal nerve lesions considering functional preservation, operative difficulty, preference of each surgeon, and quantity of specimen to be removed.

Bony surface registration of navigation system in the lateral or prone position: technical note

BackgroundNavigation systems have become essential tools in neurosurgery. Precise registration is indispensable for the accuracy of navigation. The rapid and precise registration by surface matching on the facial skin is possible using the landmarks of the face in the supine position. On the other hand, incomplete registration often occurs in the lateral or prone position due to the direction of the face and displacement of the skin by headpins and obscuring of the skin by the bispectral index monitor and many electrodes on the forehead as well as the eye patch. Surface matching on the occipital scalp is not suitable for registration because the shape of the occipital scalp is flat and it is compressed in the supine position when obtaining preoperative neuroimaging. To overcome this problem, the authors have developed a new method of registration designated as “bony surface registration” in which surface matching is achieved using the bony surface of the skull after exposure.MethodsBetween June and December 2014, this technique was used in 23 patients and its effectiveness was examined.ResultsRegistration time was markedly shortened and useful navigation was achieved due to accurate registration in all patients.ConclusionsThis is the first report of a registration methodology for a navigation system in the lateral or prone position. This bony surface registration method is useful for navigation system image-guided surgery in the lateral or prone position.

Subtemporal transtentorial approach for recurrent trigeminal neuralgia after microvascular decompression via the lateral suboccipital approach: case report.

Microvascular decompression (MVD) via lateral suboccipital craniotomy is the standard surgical intervention for trigeminal neuralgia (TN). For recurrent TN, difficulties are sometimes encountered when performing reoperation via the same approach because of adhesions and prosthetic materials used in the previous surgery. In the present case report the authors describe the efficacy of the subtemporal transtentorial approach for use in recurrent TN after MVD via the lateral suboccipital approach. An 86-year-old woman, in whom an MVD via a lateral suboccipital craniotomy had previously been performed for TN, underwent surgery for recurrent TN via the subtemporal transtentorial approach, which provided excellent visualization of the neurovascular relationships and the trigeminal nerve without adhesions due to the previous surgery. Her TN disappeared after the MVD. The present approach is ideal for visualizing the trigeminal root entry zone, and the neurovascular complex can be easily dissected using a new surgical trajectory. This approach could be another surgical option for reoperation when the previous MVD had been performed via the suboccipital approach.

Significance of surgical management for cystic prolactinoma

PurposeIt is generally accepted that dopamine agonists (DA) represent the first-line treatment for most patients with prolactinoma, and patients become candidates for surgical intervention when DA is contraindicated. Surgical indication for cystic prolactinoma remains controversial. This study was performed to investigate the significance of surgery for cystic prolactinoma.MethodsA total of 28 patients that underwent transsphenoidal resection of prolactinoma between February 2004 and May 2016 were reviewed. Five consecutive patients with cystic prolactinoma were included in this study. Our surgical strategy for cystic prolactinoma was categorized as follows: first, when the purpose of surgical resection was normalization of the prolactin level, aggressive resection was performed; second, when volume reduction was essential to relieve the visual symptoms and headache, internal decompression was performed followed by DA therapy. The clinical outcomes were analyzed accordingly.ResultsAll cystic prolactinoma were resected via the transsphenoidal approach without any complications, and all symptoms including visual impairment and hypogonadal activity were finally relieved combined with medication.ConclusionsSurgery for cystic prolactinoma could be a better option. Transsphenoidal surgery is relatively safe to remove the cystic prolactinoma, additionally it can normalize the prolactine level and achieve adequate and rapid decompression of optic chiasm. The risk of transsphenoidal surgery is highly dependent on the skill of the surgeon and treatment decision for cystic prolactinoma needs to be individualized for each patient.

Relationship Between Muscle Dissection Method and Postoperative Muscle Atrophy in the Lateral Suboccipital Approach to Vestibular Schwannoma Surgery.

BACKGROUND Various techniques are available for occipital skull exposure with muscle dissection, as well as different types of skin incisions in the lateral suboccipital approach to vestibular schwannoma (VS) surgery. The skin incisions are generally classified as S-shaped, J-shaped, or C-shaped. In each method, the technique used for muscle dissection differs in terms of cut, single layer, and multiple layers. This study was performed to identify the relationships among muscle dissection method, skin incision type, and muscle atrophy in the lateral suboccipital approach to surgery for VS. METHODS Between 2002 and 2011, we performed surgical resection in 53 patients with VS at Shinshu University Hospital. Of these 53 patients, 35 with radiographic annual follow-up for >3 years after surgery were evaluated retrospectively. These patients included 14 who underwent an S-shaped incision, 6 with a J-shaped incision, and 15 with a C-shaped incision. Bilateral areas of the skin and occipital muscles were measured, and rates of atrophy were calculated and compared among the 3 methods. RESULTS Postoperative muscle atrophy was significantly advanced in the second postoperative year, but did not tend to develop further after the third year. The postoperative muscle atrophy ratio was significantly lower in the C-shaped incision group (mean ± SD, 4.0% ± 6.9%) compared with the S-shaped (17.1% ± 9.8%) and J-shaped (17.6% ± 10.0%) incision groups within 2 years after surgery (P < 0.05). CONCLUSIONS The C-shaped skin incision with multilayer muscle dissection was associated with significantly reduced postoperative muscle atrophy compared with the other methods.

Petroclival tension pneumocephalus: an unrivalled life threatening complication linked to molecular-targeted therapy

A 73-year-old man with a petroclival tumor (metastatic renal cell carcinoma) presented with a progressive consciousness disturbance attributed to tension pneumocephalus during molecular-targeted therapy following low-dose fractionated radiotherapy for a petroclival tumor. The skull base defect was successfully reconstructed vi an endoscopic endonasal approach.

Endoscopic transpalpebral transorbital anterior petrosectomy: does “safer surgical freedoms” necessitates modifications?

Dear Editor: We have read with great consideration the paper BEndoscopic transorbital route to the petrous apex: a feasibility anatomic study,^ by Professor Paolo Cappabianca and colleagues [3]. The authors [3] presented an excellent qualitative stepwise endoscopic transpalpebral transorbital route to the petrous apex with adequate petrous apicectomy. Additionally, they were able to delineate three anatomic spaces (cerebellopontine angle, middle tentorial incisura, and ventral brainstem) and they analyzed the limitations of their technique [3]. As our lead author (A.N.) is involved in the endoscopic transorbital anatomical studies and collecting novel data [4], he would like to ask the authors [3] about specific surgical nuances that might allow surgeons to create an ideal surgical space with safer exposure and good maneuverability that evolved from combinations of pearls from multiple approaches [1–5] while avoiding major drawbacks. Based on our lead author’s (A.N.) experience with anatomic transorbital anterior petrosectomy (Fig. 1), such techniques are not without disadvantages. The exceptionally deep-narrow surgical corridor and the crowding of surgical instruments forces the surgeon to become accustomed to uncomfortable maneuverability and place the orbit and the lacrimal gland at a great risk. Therefore, our lead author (A.N.) now opt, instead, for adding endoscopic endonasal medial orbital apex decompression (might extend to the nasolacrimal duct) before starting the transorbital approaches to the regions beyond the orbital cone to avoid several drawbacks (Fig. 1). By carefully studying the degree of safe surgical freedom at the area of exposure at entry site in the presented technique [3], we would like to ask about: