Approaches to the ventral aspect of the foramen magnum and jugular foramen are difficult because of their deep locations, and they require a thorough understanding of both the anatomy and the direction of the surgical view. Approaches to the ventral foramen magnum can be divided into 1) the lateral approach with mastoidectomy, and 2) the dorsolateral approach without mastoidectomy, both of which requires partial resection of the posterior occipital condyle. The author mostly uses the latter because it advantageously avoids lower cranial nerve injuries. Approaches to the jugular foramen can also be divided into 1) the posterolateral approach with mastoidectomy, and 2) the posterior approach without mastoidectomy, which should be selected based on lesion extension. To maximally utilize the space obtained by bone resection, selecting an approach based on the approach direction is of prime importance.

View full abstract

  The cranio-cervical junction (CCJ) is a gateway to many vital structures such as the carotid and vertebral arteries, the pharynx and the spinal cord. It is also the pivotal center of head movement. Therefore, the CCJ has a sophisticated anatomy in order to avoid problems between these contradicting demands. For successful surgical intervention, it is therefore necessary to thoroughly comprehend the anatomical characteristics of the atlas and the axis. Another important aspect is the course of the cranial nerves. The main goals of the surgery are to achieve decompression of the neural tissue and to assure competence of the spinal column. On the other hand, restriction of the head motion should be minimized.
  There are several routes available for this surgical approach, including the transoral, anterior, anterolateral, posterior, transcondylar and posterolateral. The best procedure should be selected according the location and size of the lesion. The stability of the spine should also be considered to decide if additional posterior fixation is necessary. Some unique screw placements have been proposed in the previous literature. Generally, lateral mass screw fixation is the most common technique used for the atlas. For the axis, there are three methods : pedicle, translaminar and pars screw fixation. Preoperative images should be carefully analyzed to choose the best screw type.

View full abstract

  Most of pediatric lesions in the craniovertebral junction (CVJ) are derived from congenital bony anomalies. Understanding the emobryology of CVJ and spinal formation following resegmentation is important to disclose any bony anomalies present in the pediatric CVJ.
  Developmental process of the CVJ comprises ossification and resegmentation of the somite. Most of the skull and facial bones are formed by membranous ossification while the occipital bone and spinal column are formed by endochondral ossification. The CVJ is a transitional region of the both ossification. In addition, ossification progresses throughout childhood. The C1 tubercle is absent at birth and appears at 6 months and thereafter. Additionally, the C2 odontoid process and vertebral body are separated by synchondorosis. The C1 ossification is complete at 5-13 years of age while the C2 is complete at 10-13 years of age.
  Resegmentation at the CVJ is complicated. The foramen magnum is derived from the 4th somite while the C1 derives from the 5th one. Three sclerotomes participate in the formation of the C2. Abnormal resegmentation leads to the formation of fused or hemi-vertebra.
  Knowledge of the CVJ embryonal process is integral to a thorough understanding of the surgical anatomy and is therefore extremely helpful in planning the surgery.

View full abstract

  With the recent advent of endoscopic technology, the role of endoscopic transnasal surgery has been remarkably enlarged in skull base surgery. Using the endoscopic skull base approach, we can reach a wide range of skull base regions, including the craniovertebral junction. Additionally, the technique of endoscopic skull base surgery is relatively easier to master than that of conventional skull base surgery with microscope, but there are some anatomical remarks that need to be addressed. In this article, we present our experience using the endoscopic transnasal approach to treat lesions in the craniovertebral junction. After carefully observing the nasal cavity, the endoscope is advanced along the inferior nasal turbinate, whereby the upper pharynx, soft palate, and bilateral torus tubarius are exposed. The upper pharynx mucosa is then dissected and the prevertebral muscles are removed. At this point, any lesions located in the lower clivus and the perimedullary cistern will be disclosed and can now be safely approached via this route. The endoscopic transnasal skull base approach is one of the least invasive surgical procedures, and it is a very promising therapeutic choice with a potential for further advancement. Hopefully, this article will contribute to the ongoing pursuit of the safe and effective surgical procedures and ultimately to the benefit those patients suffering from intractable skull base lesions in the craniovertebral junction.

View full abstract

  The results of radiosurgery in patients with facial schwannoma, 6 males and 12 females, mean age 47.1 years, are reported. Most of the patients presented with facial palsy (12/17) and/or hearing disturbance (13/18). Prior treatments consist of tumor resection or tumor biopsy in 9 out of 18 cases. Tumor volume ranged from 0.9 to 20.8 cc and the mean tumor volume was 5.0 cc. At radiosurgery the tumors were treated with a mean maximum and marginal dose of 24.2 Gy and 12.7 Gy respectively.
  During the mean follow-up period of 41.1 months (range : 12-240 months), one tumor disappeared, 10 tumors apparently shrank, and 7 were unchanged. Thus the tumor response rate and tumor control rate were 61.1% and 100% respectively. No subsequent surgical resection was required. Facial nerve function was intact or improved in 9 cases, unchanged in 7 cases and became temporarily worse in 2 cases due to adverse effect. There were no changes of hearing function in 16 and even worse in 2 cases. Complications consist of the development of facial palsy in two patients within 1 to 3 days after treatment with subsequent recovery to House and Brackmann Grade I and II.
  In conclusion, radiosurgery as a method of treating facial schwannoma is found to be very useful, not only for the tumor control, but for the functional control and recovery. Radiosurgery, therefore, should be the first choice of the treatments for facial schwannomas.

View full abstract

  The authors compared the utility of the International Prostate Symptom Score (IPSS) and the Japan Orthopaedic Association (JOA) score for evaluating lower urinary tract symptoms (LUTS) associated with cervical degenerative myelopathy.
  A total of 128 patients with cervical degenerative myelopathy were assessed according to the IPSS and JOA score. These included 31 females (F-group), 61 males without urinary tract lesions (Mn-group), and 36 males with urinary tract lesions (Mu-group). Patients with ＞8 points on the IPSS and ≦2 points on the JOA score were classified as LUTS (+). Additionally, we investigated both storage and voiding symptoms using the IPSS. Patients with ≧4 points from a possible maximum of 15 across 3 questions relating to storage and voiding symptoms on the IPSS were defined as symptom (+).
  Among all 128 patients, LUTS positivity was detected in 58 patients (45%) by the IPSS and in 52 patients (41%) by the JOA score. In the F-group, 13 (42%) and 10 patients (32%) were LUTS (+) based on the IPSS and JOA score, respectively. In the Mn-group, 23 (38%) and 20 patients (33%) were LUTS (+) based on the IPSS and JOA score, respectively. Thus, there was good correlation between the IPSS and JOA score.
  However, a more detailed analysis of the findings revealed that the group defined as normal by the JOA score had worse symptoms on the IPSS : 24% of the 128 patients, including 24% in the F-group and 22% in the Mn-group. In addition, it was revealed that the group defined as slight by the JOA score had a wide range of symptoms from 2 to 27 on the IPSS. Moreover, a significant difference was not observed in IPSS between the slight group and severe groups according to the JOA score.
  Also from another viewpoint, IPSS clearly identified many cases with voiding symptoms and many mixed cases with both voiding and storage symptoms associated with cervical degenerative myelopathy.
  In conclusion, IPSS was considered to be a more sensitive and useful scoring system than the JOA score for evaluating LUTS associated with cervical degenerative myelopathy.

View full abstract

  The authors have developed percutaneous subdural tapping as minimum invasive treatment particularly for the aged patients with chronic subdural hematoma. As the ultimate application, replacement of hematoma with oxygen has been adopted to remove most of the hematoma without saline irrigation. The technical details of this treatment are described, in addition to valuable points of minimum invasiveness.

View full abstract

  Synovial cysts are a common accompaniment of osteoarthritis in the lumbar spine, causing pain and neurological symptoms. Bleeding within the cyst generally leads to changes in intensity and can cause neurological deterioration and/or painful symptoms that are violent and generally intractable. We present here an interesting case of hemorrhage in a synovial cyst while the patient was waiting for surgery. A 64-year-old man, who was on anti-platelet therapy, presented with severe lumbago and pain over the left lower extremity during gardening, which had persisted for two months. The initial magnetic resonance imaging (MRI) scan revealed a space occupying the intraspinal lesion that was close to the facet joint at the left L4-L5. His lumbago and pain over his left lower extremity suddenly deteriorated while he was waiting for his surgery. A follow-up MRI revealed signal changes of the lesion, which indicated a hemorrhagic change in the cyst. During surgery, this was proven to be a hemorrhagic mass on the left L5 root sleeve, arising from the facet joint. There was no epidural vascular lesion present. The operation dramatically relieved the patient's symptoms. The diagnosis was confirmed by the histopathological analysis, which presented partially synovial lining cells and a capsule with intracystic bleeding. These pathological findings coincided with the clinical and the radiological findings. MRI is useful for diagnosing hemorrhage of which will show changes in its intensity depending on its onset. The post-operative results following hemorrhagic synovial cyst excision are excellent, if they are treated in the early stage. Surgical treatment should be performed as soon as possible in order to prevent any post operative residual neurological deficit.

View full abstract