Yu-Shu Yen

Endoscopic transnasal transclival odontoidectomy: a new approach to decompression: technical case report.

OBJECTIVE Endoscopic transnasal transclival resection of the odontoid process is less invasive than the standard transoral odontoidectomy. In this article, we describe our techniques, which are less invasive but provide successful decompression. CLINICAL PRESENTATION From September 2004 to April 2007, three consecutive patients with basilar invagination and instability in the craniovertebral junction were enrolled. The causes for the invagination and instability included rheumatoid arthritis in two patients and trauma in one patient, and all patients presented with myelopathy and quadriparesis before intervention. INTERVENTION All three patients underwent an endoscopic transnasal transclival approach for anterior decompression and resection of the displaced odontoid process and pannus to decompress the underlying medulla. Subsequently, they received occipitocervical fixation by lateral mass screws and bone fusion to ensure stability. Remarkable neurological recovery was observed after surgery in all patients, and no adverse effects were noted. CONCLUSION Compared with the standard transoral approach, the transnasal transclival endoscopic approach for decompressing basilar invagination is a feasible and effective alternative that avoids common disadvantages like prolonged intubation, excessive tongue retraction, and the need for palatal incision.

Epidemiology of cervical spondylotic myelopathy and its risk of causing spinal cord injury: a national cohort study

OBJECT This study aimed to determine the age- and sex-specific incidence of cervical spondylotic myelopathy (CSM) and its associated risk of causing subsequent spinal cord injury (SCI). METHODS Using the National Health Insurance Research Database (NHIRD), a 12-year nationwide database in Taiwan, this retrospective cohort study analyzed the incidence of hospitalization caused by CSM. All patients diagnosed with and admitted for CSM were identified during the study period. The CSM patients were divided into 2 groups, a control group and an operated group. An incidence density method was used to estimate age- and sex-specific incidence rates of CSM. The Kaplan-Meier method and Cox regression analyses were performed to compare the risk of SCI between the 2 groups. RESULTS From 1998 to 2009, covering 349.5 million person-years, 14,140 patients were hospitalized for CSM. The overall incidence of CSM-related hospitalization was 4.04 per 100,000 person-years. Specifically, males and older persons had a higher incidence rate of CSM. During the follow-up of these patients for 13,461 person-years, a total of 166 patients were diagnosed with SCI. The incidence of SCI was higher in the control group than the operated group (13.9 vs 9.4 per 1000 person-years, respectively). During the follow-up, SCI was more likely to occur in CSM patients who were treated conservatively (crude HR 1.48, p = 0.023; adjusted HR 1.57, p = 0.011) than in those who underwent surgery for CSM. CONCLUSIONS In a national cohort of eastern Asia, the incidence of CSM-caused hospitalization was 4.04 per 100,000 person-years, with higher incidences observed in older and male patients. Subsequent SCI was more likely to develop in patients who received nonoperative management than in those who underwent surgery. Therefore, patients with CSM managed without surgery should be cautioned about SCI. However, further investigations are still required to clarify the risks and complications associated with surgery for CSM.

ENDOSCOPIC TRANSNASAL TRANSCLIVAL ODONTOIDECTOMY: A NEW APPROACH TO DECOMPRESSION

OBJECTIVE Endoscopic transnasal transclival resection of the odontoid process is less invasive than the standard transoral odontoidectomy. In this article, we describe our techniques, which are less invasive but provide successful decompression. CLINICAL PRESENTATION From September 2004 to April 2007, three consecutive patients with basilar invagination and instability in the craniovertebral junction were enrolled. The causes for the invagination and instability included rheumatoid arthritis in two patients and trauma in one patient, and all patients presented with myelopathy and quadriparesis before intervention. INTERVENTION All three patients underwent an endoscopic transnasal transclival approach for anterior decompression and resection of the displaced odontoid process and pannus to decompress the underlying medulla. Subsequently, they received occipitocervical fixation by lateral mass screws and bone fusion to ensure stability. Remarkable neurological recovery was observed after surgery in all patients, and no adverse effects were noted. CONCLUSION Compared with the standard transoral approach, the transnasal transclival endoscopic approach for decompressing basilar invagination is a feasible and effective alternative that avoids common disadvantages like prolonged intubation, excessive tongue retraction, and the need for palatal incision.

Gamma Knife Radiosurgery for Central Neurocytoma: Retrospective Analysis of Fourteen Cases with a Median Follow-Up Period of Sixty-Five Months

Object: Central neurocytoma (CN) is considered to be a benign neuronal tumor with possible atypical behavior. Microsurgery, radiation therapy (RT) and radiosurgery all have been used in treating this rare disease during the past decade. In this study, the authors present the experience with gamma knife radiosurgery (GKRS) on 14 patients with CN during a median follow-up period of 65 months and document the safety and efficacy of GKRS in the treatment of CN. Methods: Between November 1997 and December 2009, 14 patients pathologically diagnosed with CN were treated with GKRS. Follow-up magnetic resonance imaging (MRI) was performed at 6-month intervals. Tumor volume and adverse radiation effects (ARE) were documented to evaluate tumor response to GKRS. The Karnofsky Performance Scale (KPS) and neurological status were used to assess clinical outcome. The mean radiation dose prescribed to the tumor margin was 12.1 Gy (ranging from 11 to 13 Gy). The mean tumor volume was 19.6 ml (ranging from 3.5 to 48.9 ml). The mean follow-up period was 70 months (ranging from 30 to 140 months), and the median follow-up period was 65 months. Results: Tumor shrinkage was found in all patients at the final MRI follow-up. The mean volume reduction was 69% (ranging from 47 to 87%). No tumor progression, ARE or radiation-related toxicity developed in any of the cases. The KPS scores of all patients were the same or had increased, and the neurological functions were all stable without deterioration at the final follow-up. Conclusion: In our observations, GKRS was found to be an effective and safe alternative as adjuvant therapy for pathology-confirmed CN. The tumor volume and functional outcome can be controlled with a favorable result in long-term observation. Compared with RT and microsurgery, GKRS plays an important role in the treatment of CN as a minimally invasive technique with low morbidity. Regular long-term MRI follow-up should be mandatory to document the tumor response and possible recurrence. Multicenter consortia should be considered for further investigation and evaluation of GKRS for such a rare tumor.

Large vestibular schwannomas treated by Gamma Knife surgery: long-term outcomes

OBJECT Although radiosurgery has been well accepted as a treatment for small- to medium-sized vestibular schwannomas (VSs), its application in the treatment of large VSs remains controversial because of unfavorable effects such as tumor swelling and potential compression of the brainstem. The authors present a retrospective study spanning 17 years, during which 21 patients underwent Gamma Knife surgery (GKS) for large VSs. Long-term outcomes are reported, and possible factors affecting tumor responses to GKS are analyzed. METHODS Five hundred thirteen patients harboring VSs underwent GKS between March 1993 and October 2009. A large VS was defined as a tumor whose diameter was > 3 cm. This paper focuses on 21 patients who harbored large VSs ranging in volume from 12.7 to 25.2 cm(3) (mean 17.3 cm(3)) and were treated by GKS. Fourteen of these patients had undergone 1 or more craniotomies previously to remove the tumor. Seven patients underwent GKS alone because of patient preference or a poor clinical condition that precluded microsurgery with general anesthesia. The mean radiation dose directed to the tumor ranged from 15 to 17.5 Gy. The mean radiation dose prescribed to the tumor margin was 11.9 Gy (range 11-14 Gy). The mean follow-up period was 66 months (range 12-155 months), and the median follow-up period was 53 months. RESULTS The tumor control rate was 90.5% (19 of 21 lesions). No deterioration in facial nerve or trigeminal nerve function was noted. Disturbances in balance (some temporary) occurred in 5 patients. Three of the 21 patients developed initial tumor swelling, which required minor surgical interventions, including aspiration using an Ommaya reservoir or placement of a ventriculoperitoneal shunt. All 3 patients recovered satisfactorily after aspiration of an enlarging cyst or ventriculoperitoneal shunt placement. There was no significant correlation between tumor control and the following factors: patient age or sex, tumor volume, radiation dose, previous operation, presence of brainstem compression, petrous bone invasion, T2 signal ratio between tumor and brainstem, and presence of a cyst. However, there was a significant correlation between the T2 signal ratio between tumor and brainstem and the duration of tumor swelling (p = 0.003). CONCLUSIONS Treatment of large VSs remains a challenge to neurosurgeons regardless of whether they perform microsurgery or radiosurgery. Control of tumor growth and preservation of neurological function are the main goals of treatment. Although delayed microsurgery was required in 2 patients (9.5%), the satisfactory tumor control rate and excellent preservation of facial and trigeminal nerve function are the great advantages of radiosurgery. Radiosurgery is not only a practical treatment for patients with small- to medium-sized VSs, but it is also an excellent tool for treating larger tumors up to 25 cm(3). In selected cases, radiosurgery plays an important role in treating large VSs with satisfactory results.

Exclusion of histiocytes/endothelial cells and using endothelial cells as internal reference are crucial for interpretation of MGMT immunohistochemistry in glioblastoma.

We evaluated the predictive value of O6-methylguanine-DNA methyltransferase (MGMT) protein expression and MGMT promoter methylation status in glioblastomas (GBM) treated with temozolomide (TMZ) in a Taiwan medical center. Protein expression by immunohistochemical analysis (IHC) and MGMT promoter methylation detected by methylation-specific polymerase chain reaction (MSP) were performed in a series of 107 newly diagnosed GBMs. We used endothelial cells as an internal reference for IHC staining because the staining intensities of the MGMT-expressing cells in different specimens varied considerably; a positive result was defined as the staining intensity of the majority of tumor cells similar to that of the adjacent endothelial cells. Immunostainings for microglial/endothelial markers were included as part of the MGMT IHC evaluation, and in cases that were difficult to interpret, double-labeling helped to clarify the nature of reactive cells. The MGMT protein expression was reversely associated with MGMT promoter methylation status in 83.7% of cases (MSP+/IHC− and MSP−/IHC+; Pearson r=−0.644, P<0.001). Twenty-two of 24 (91.7%) IHC+ tumors did not respond to TMZ treatment. Combining MSP and IHC results, all the 15 MSP−/IHC+ GBMs were TMZ resistant. The MGMT status detected by either IHC or MSP was significantly correlated with the TMZ treatment response (both P<0.001) and survival of GBM patients (both P<0.05).

Endoscopic transnasal odontoidectomy without resection of nasal turbinates: clinical outcomes of 13 patients

Object The goal of the study was to report a series of consecutive patients who underwent endoscopic transnasal odontoidectomy (ETO) without resection of nasal turbinates. The techniques for this minimally invasive approach are described in detail. Methods The authors conducted a retrospective review of consecutive patients who underwent ETO for basilar invagination. All the patients had myelopathy caused by compression at the cervicomedullary junction, which required surgical decompression. Preoperative and postoperative data, including those from radiographic and clinical evaluations, were compared. Morbidity and mortality rates for the procedure are also reported in detail. Results Thirteen patients (6 men and 7 women) with a mean age of 52.7 years (range 24-72 years) were enrolled. The basilar invagination etiologies were rheumatoid arthritis (n = 5), trauma (n = 4), os odontoideum (n = 2), ankylosing spondylitis (n = 1), and postinfectious deformity (n = 1). The average follow-up duration was 51.2 months (range 0.3-105 months). One patient died 10 days after the operation as a result of meningitis caused by CSF leakage. Among the other 12 patients, the average postoperative Nurick grade (3.2) was significantly improved over that before the operation (4.1, p = 0.004). The mean (± SD) duration of postoperative intubation was 1.5 ± 2.1 days, and there was no need for perioperative tracheostomy or nasogastric tube feeding. There also was no postoperative velopharyngeal insufficiency. There were 6 (46%) intraoperative and 2 (15%) postoperative CSF leaks in the 13 patients in this series. Conclusions ETO is a viable and effective option for decompression at the ventral cervicomedullary junction. This approach is minimally invasive and causes little velopharyngeal insufficiency. The pitfall of this approach is the difficulty in repairing dural defects and subsequent CSF leakage.

Posterior transarticular screw fixation for chronic atlanto-axial instability.

Treatment for chronic atlanto-axial instability remains problematic despite recent innovations in new surgical techniques and instrumentation. Our team reviewed a series of 23 cases of patients with chronic atlanto-axial instability who underwent posterior transarticular screw fixation operations between May 1998 and September 2002. Etiologies of these patients included failed prior surgery, rheumatoid arthritis, congenital anomalies and old odontoid fractures. The clinical presentations were nuchal pain and cervical myelopathy or radiculopathy, with sensory and/or motor deficits that persisted for more than 3 months. We routinely used external reduction to realign the C1-C2 axis prior to operating, and operated on patients using halo-vest fixation. After surgery, the halo-vest was replaced by a collar. In the post-operative follow-up, 22 of the 23 patients (96%) were found to have achieved solid, bony or fibrous union of the C1-C2 axis. Eleven of the 14 (79%) patients with pre-operative neck pain experienced immediate relief or significant improvement. Thirteen of the 20 patients (65%) with myelo-radiculopathy demonstrated improvement of previous motor deficits. Major morbidity included a vertebral artery (VA) injury and a malpositioned screw. No cases of mortality or neurological complications occurred in this series. Posterior transarticular C1-C2 screw fixation results in a high fusion rate without the additional need for rigid external immobilization. It allows good neurological recovery in cases of chronic atlanto-axial instability. Judicious pre-surgical planning and meticulous operative technique may avoid neurological complications and vertebral artery injury.

Plasma corticotrophin response to desmopressin in patients with Cushing's disease correlates with the expression of vasopressin receptor 2, but not with that of vasopressin receptor 1 or 3, in their pituitary tumours

Objectives  Most patients with Cushing’s disease (CD) respond to corticotrophin‐releasing hormone (CRH) or desmopressin with increased corticotrophin (ACTH) and cortisol levels. Although the vasopressin receptor subtype located on normal corticotrophs is the V3 receptor (V3R), desmopressin is a selective V2 receptor (V2R) agonist and it is unclear whether corticotrophinomas exhibit aberrant V2R expression. Furthermore, no studies have determined the relationship between the in vivo response of CD patients to desmopressin and vasopressin receptor expression, or between the response to CRH and CRH receptor (CRHR) expression. Therefore, the aim of this study was to investigate the expression of vasopressin receptors (V1R, V2R, and V3R) and CRHR on corticotroph tumours and its possible relation to the in vivo response.

Brainstem auditory evoked potential monitoring and neuro-endoscopy: Two tools to ensure hearing preservation and surgical success during microvascular decompression

Background: The effectiveness of microvascular decompression (MVD) has made trigeminal neuralgia (TN), hemifacial spasm (HFS), glossopharyngeal neuralgia, and other cranial nerve rhizopathy diseases treatable by surgery. To ensure hearing preservation and surgical success, we have presented our experience in the application of brainstem auditory evoked potential (BAEP) monitoring and neuro‐endoscopy during MVD. Methods: From July 2007 to October 2012, a total of 93 patients in our institution received MVD for cranial nerve rhizopathies. Among these patients, 43 had both BAEP monitoring and endoscope‐assisted microsurgery for their MVD. None of the patients had undergone previous surgical treatment. Postoperative outcomes were assessed based on the medical records and clinical follow‐up. Results: This study included 32 women and 11 men. There were 36 HFS cases and seven TN cases, and the median patient age at the time of MVD was 48 years. The median duration of symptoms before MVD was 4.2 years, and the median follow‐up duration was 3.5 years (range 1.5 months–5 years). All of the patients had either immediate or delayed complete relief from the symptoms after MVD. One TN patient underwent gamma knife radiosurgery 3 years after MVD, and two HFS cases had recurrent slight spasms, which warranted no further treatment. There was no surgical mortality. The major complications included one HFS patient with delayed and permanent hearing loss and facial palsy, which occurred 1 week after MVD. The surgical success rate was 100%, and the hearing complication rate was 2%. Conclusion: The results of this retrospective study emphasized the importance of BAEP monitoring and neuro‐endoscopy during MVD. It is well known that BAEP monitoring can preserve hearing function, and the endoscope offers neurosurgeons a second look to identify the nerve root entry zone and confirms the position of the Teflon felt. These two tools are especially useful in difficult cases.