Basilar Invagination: Case Report and Literature Review

BACKGROUND

Basilar invagination is a rare clinical condition characterized by upward protrusion of the odontoid process into the intracranial space, leading to bulbomedullary compression. It is often encountered in adults with rheumatoid arthritis. Transoral microscopic or endonasal endoscopic decompression may be pursued, with or without posterior fixation. We present a case of basilar invagination with C1-C2 autofusion and discuss an algorithm for choice of anterior versus posterior approaches.

CASE DESCRIPTION

A 47-year-old woman with rheumatoid arthritis presented with severe occipital and cervical pain, dysphagia, hoarseness, and arm paresthesias. Findings on magnetic resonance imaging revealed moderate cranial settling with the odontoid indenting the ventral medulla but no posterior compression. Computed tomography demonstrated bony fusion at C1-C2 without lateral sag. Given autofusion of C1-C2 in proper occipitocervical alignment and the absence of posterior compression, the patient underwent endoscopic endonasal odontoidectomy without further posterior fusion, with satisfactory resolution of symptoms.

CONCLUSION

Endoscopic endonasal odontoidectomy offers a safe and effective method for anterior decompression of basilar invagination. Preoperative assessment for existing posterior fusion, absence of posterior compression, and preservation of the anterior C1 ring during operative decompression help stratify the need for lone anterior approach versus a combined anterior and posterior treatment.

Endoscopic endonasal atlantoaxial transarticular screw fixation technique: an anatomical feasibility and biomechanical study

OBJECT The primary disadvantage of the posterior cervical approach for atlantoaxial stabilization after odontoidectomy is that it is conducted as a second-stage procedure. The goal of the current study is to assess the surgical feasibility and biomechanical performance of an endoscopic endonasal surgical technique for C1-2 fixation that may eliminate the need for posterior fixation after odontoidectomy. METHODS The first step of the study was to perform endoscopic endonasal anatomical dissections of the craniovertebral junction in 10 silicone-injected fixed cadaveric heads to identify relevant anatomical landmarks. The second step was to perform a quantitative analysis using customized software in 10 reconstructed adult cervical spine CT scans to identify the optimal screw entry point and trajectory. The third step was biomechanical flexibility testing of the construct and comparison with the posterior C1-2 transarticular fixation in 14 human cadaveric specimens. RESULTS Adequate surgical exposure and identification of the key anatomical landmarks, such as C1-2 lateral masses, the C-1 anterior arch, and the odontoid process, were provided by the endonasal endoscopic approach in all specimens. Radiological analysis of anatomical detail suggested that the optimal screw entry point was on the anterior aspect of the C-1 lateral mass near the midpoint, and the screw trajectory was inferiorly and slightly laterally directed. The custommade angled instrumentation was crucial for screw placement. Biomechanical analysis suggested that anterior C1-2 fixation compared favorably to posterior fixation by limiting flexion-extension, axial rotation, and lateral bending (p > 0.3). CONCLUSIONS This is the first study that demonstrates the feasibility of an endoscopic endonasal technique for C1-2 fusion. This novel technique may have clinical utility by eliminating the need for a second-stage posterior fixation operation in certain patients undergoing odontoidectomy.

Endoscopic Transnasal Approach for Urgent Decompression of the Craniocervical Junction in Acute Skull Base Osteomyelitis

Ventral epidural abscess with osteomyelitis at the craniocervical junction is a rare occurrence that typically mandates spinal cord decompression via a transoral approach. However, given the potential for morbidity with transoral surgery, especially in the setting of immunosuppression, together with the advent of extended endonasal techniques, the transnasal approach could be attractive for selected patients. We present two cases of ventral epidural abscess and osteomyelitis at the craniocervical junction involving C1/C2 that were successfully treated via the endoscopic transnasal approach. Both were treated in staged procedures involving posterior cervical fusion followed by endoscopic transnasal resection of the ventral C1 arch and odontoid process for decompression of the ventral spinal cord and medulla. Dural repairs were successfully performed using multilayered, onlay techniques where required. Both patients tolerated surgery exceedingly well, had brief postoperative hospital stays, and recovered uneventfully to their neurologic baselines. Postoperative magnetic resonance imaging confirmed complete decompression of the foramen magnum and upper C-spine. These cases illustrate the advantages and low morbidity of the endonasal endoscopic approach to the craniocervical junction in the setting of frank skull base infection and immunosuppression, representing to our knowledge a unique application of this technique to osteomyelitis and epidural abscess at the craniocervical junction.

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.

To repeat or to recreate: a contralateral posterior interhemispheric transfalcine transprecuneus approach for recurrent meningiomas at the trigone of the lateral ventricle

Surgery in the trigone of the lateral ventricle remains a challenge for neurosurgeons. In recurrent trigonal meningiomas (RTM), the disturbance of normal anatomic structures and adhesion due to previous surgeries, significant oedema, and their malignant properties heighten the difficulties associated with their surgical removal. This report presents two patients with recurrent meningiomas with anaplastic transformation at the trigone of the lateral ventricle who were successfully treated with contralateral posterior interhemispheric transfalcine transprecuneus (CITT) surgeries. The primary tumours were both completely removed through a transparietal approach in previous surgeries, but both patients experienced hemianopsia postoperatively. The second surgeries resulted in the complete resection of the recurrent tumours without any new-onset neurological dysfunction. The CITT approach suits most trigonal lesions with advantages of optic radiation preservation, reduction of retraction, improved exposure, and navigation accuracy, and because it addresses the origin of the trigonal lesion. Although the characteristics of RTM heighten the difficulty associated with their surgical removal, these challenges highlight the advantages of the CITT approach. In conclusion, the CITT approach is a safe and effective procedure for the removal of RTM.

Experience with intraoperative navigation and imaging during endoscopic transnasal spinal approaches to the foramen magnum and odontoid

Object

In this study the authors share their experience using intraoperative spinal navigation and imaging for endoscopic transnasal approaches to the odontoid in 5 patients undergoing C1–2 surgery for basilar invagination at Stanford Hospital and Clinics from 2010 to 2013.

Methods

Of these 5 patients undergoing C1–2 surgery for basilar invagination, 4 underwent a 2-tiered anterior C1–2 resection with posterior occipitocervical fusion during a first stage surgery, followed by endoscopic endonasal odontoidectomy in a separate setting. Intraoperative stereotactic navigation was performed using a surgical navigation system in all cases. Navigation accuracy, characterized as target registration error, ranged between 0.8 mm and 2 mm, with an average of 1.2 mm. Intraoperative imaging using a CT scanner was also performed in 2 patients.

Results

Endoscopic decompression of the brainstem was achieved in all patients, and no intraoperative complications were encountered. All patients were extubated within 24 hours after surgery and were able to swallow within 48 hours. After appropriate initial reconstruction of the defect at the craniocervical junction, no postoperative CSF leakage, arterial injury, or need for reoperation was encountered; 1 patient developed mild postoperative velopharyngeal insufficiency that resolved by the 6-month follow-up evaluation. There were no deaths and no patients required tracheostomy placement. The average inpatient stay after surgery varied between 72 and 96 hours, without extended intensive care unit stays for any patient.

Conclusions

Technologies such as intraoperative CT scanning and merged MRI/CT can provide the surgeon with detailed, virtual real-time information about the extent of complex endoscopic vertebral segment resection and brainstem decompression and lessens the prospect of revision or secondary procedures in this challenging surgical corridor. Moreover, patients experience limited morbidity and can tolerate early oral intake after transnasal endoscopic odontoidectomy. Essential to the successful undertaking of these endoscopic adventures is 1) an understanding of the endoscopic nasal, skull base, and neurovascular anatomy; 2) advanced and extended-length instrumentation including navigation; and 3) a team approach between experienced rhinologists and spine surgeons comfortable with endoscopic skull base techniques

Extended endoscopic endonasal approach for suprasellar Rathke's cleft cysts

Purely suprasellar Rathke's cleft cysts (RCC) treated with a microscopic endonasal approach have increased operative morbidity and poorer outcomes compared to purely sellar RCC. We sought to determine if the extended endoscopic endonasal approach improved outcomes for suprasellar RCC. We retrospectively reviewed RCC patients at our institution over a 10 year period comparing outcomes of purely sellar RCC treated microsurgically (n=68), purely suprasellar RCC treated microsurgically (n=22), and purely suprasellar RCC treated endoscopically (n=9). Suprasellar RCC treated endoscopically were similar in size to those treated microscopically (0.9 versus 1.1cm; p=0.4). Complete cyst drainage occurred in 78% of suprasellar RCC approached endoscopically versus 25% approached microsurgically (p=0.02), approaching the 84% complete drainage rate seen with sellar microsurgically approached RCC. Visual normalization occurred in 67% of suprasellar RCC patients treated endoscopically versus 29% treated microsurgically (p=0.5). Headache improved in 71% of suprasellar RCC treated endoscopically, more than the 33% of suprasellar RCC treated microsurgically and the 53% of sellar RCC treated microsurgically (p=0.4). Diabetes insipidus (all temporary) occurred in 22% of patients with suprasellar RCC treated endoscopically, slightly greater than the 14% in suprasellar microsurgical patients and 9% in sellar RCC treated microsurgically (p>0.05). Cerebrospinal fluid (CSF) leak did not occur in any of the suprasellar RCC treated endoscopically, while 14% treated microsurgically experienced a CSF leak (p>0.05). Suprasellar RCC are neurosurgically challenging due to their proximity to the optic chiasm and infundibulum. Compared to microsurgery, endoscopy improves rate of complete removal and visual outcomes.

Headache and pituitary disease: a systematic review

Headache is very common in pituitary disease and is reported to be present in more than a third of all patients with pituitary adenomas. Tumour size, cavernous sinus invasion, traction or displacement of intracranial pain-sensitive structures such as blood vessels, cranial nerves and dura mater, and hormonal hypersecretion are implicated causes. The present review attempts to systematically review the literature for any combination of headache and pituitary or hormone overproduction or deficiency. Most data available are retrospective and/or not based on the International Headache Society (IHS) classification. Whereas in pituitary apoplexy a mechanical component explains the almost universal association of the condition with headaches, this correlation is less clear in other forms of pituitary disease and a positive impact of surgery on headaches is not guaranteed. Similarly, invasion into the cavernous sinus or local inflammatory changes have been linked to headaches without convincing evidence. Some studies suggest that oversecretion of GH and prolactin may be important for the development of headaches, and treatment, particularly with somatostatin analogues, has been shown to improve symptoms in these patients. Otherwise, treatment rests on general treatment options for headaches based on an accurate clinical history and a precise classification which includes assessment of the patient's psychosocial risk factors.

Rathke's cleft cyst recurrence after transsphenoidal surgery: a meta-analysis of 1151 cases

Rathke's cleft cysts (RCC) arise from the development of the Rathke's cleft pouch. These commonly occurring cysts are typically asymptomatic, but sometimes present with headaches, endocrine dysfunction, and visual loss. Recurrence is common after either drainage or surgical removal. The purpose of this study was to review published outcomes for RCC management, and determine whether specific factors, including patient demographics, cyst pathology, radiologic parameters, or surgical techniques predispose to their recurrence. A systematic review of studies for RCC from 1990 to 2012 was conducted. Patients were identified using a Medline/PubMed search, and from the bibliographies of relevant articles obtained from the primary search. Relevant studies reporting recurrence rate were identified, and data were extracted regarding patient demographics, presenting symptoms, cyst characteristics, surgical treatment, and outcomes. A meta-analysis for recurrence rates was also performed. Twenty-eight journal articles comprising a total of 1151 RCC revealed an average follow-up of 38 months (range 16-79 months). In the studies reviewed, there was a relatively equal distribution of treatment approaches, with 35% subtotal resection, 33% gross total resection, and 32% complete drainage with wall biopsy. The microsurgical transsphenoidal approach was found to have a higher recurrence rate (14% versus 8%) and new endocrine dysfunction rate (25% versus 10%) compared to the endoscopic approach. The data demonstrates a notable overall recurrence rate for RCC (12.5%). However, there appears to be no conclusive evidence that more aggressive resection of the cyst wall results in lower rates of recurrence.

Endoscopic transnasal odontoidectomy combined with posterior reduction to treat basilar invagination: technical note

OBJECT

Transoral microscopic odontoidectomy has been accepted as a standard procedure to treat basilar invagination over the past several decades. In recent years the emergence of new technologies, including endoscopic odontoidectomy and posterior reduction, has presented a challenge to the traditional treatment algorithm. In this article, the authors describe 1 patient with basilar invagination who was successfully treated with endoscopic transnasal odontoidectomy combined with posterior reduction. The purpose of this report is to validate the effectiveness of this treatment algorithm in selected cases and describe several operative nuances and pearls based on the authors' experience.

METHODS

One patient with basilar invagination caused by a congenital osseous malformation underwent endoscopic transnasal odontoidectomy combined with posterior reduction in a single operative setting. The purely endoscopic transnasal odontoidectomy was first conducted with the patient supine. The favorable anatomical reduction was then achieved through a posterior approach after the patient was moved prone.

RESULTS

The patient was extubated after recovery from anesthesia and allowed oral food intake the next day. No complications were noted, and the patient was discharged 4 days after the operation. Postoperative imaging demonstrated excellent decompression of the anterior cervicomedullary junction pathology. The patient was followed up for 12 months and remarkable neurological recovery was observed.

CONCLUSIONS

The endoscopic transnasal odontoidectomy is a better minimally invasive approach for anterior decompression and can make the posterior reduction easier because the anterior resistant force is eliminated. The subsequent posterior reduction can make decompression of the ventral side of the cervicomedullary junction more effective because the C-2 vertebral body is pushed forward. A combination of these 2 approaches has the advantages of minimally invasive access and a faster patient recovery, and thus is a valid alternative in selected cases.

Rathke's cleft cysts

Rathke's cleft cysts (RCCs) are benign, sellar and/or suprasellar lesions originating from the remnants of Rathke's pouch. Although a common finding in routine autopsies (12-33% of normal pituitary glands), symptomatic cases are rare and comprise 5-15% of all surgically resected sellar lesions. Small, asymptomatic RCC do not require surgical intervention, and their natural history is not clear. In series of nonoperated presumed RCCs, 26-94% did not progress during follow-up periods up to 9 years. In symptomatic ones, surgery is indicated, aiming to drain the cyst content and safely remove as much of the capsule as possible. Following surgical intervention, headaches and visual field defects improve or resolve in a significant number of patients (40-100% and 33-100%, respectively) and partial hypopituitarism recovers in 14-50%. Data on relapse rates published in the last 15 years are based on variable follow-up periods and show wide variation (between 0% and 33%). The lowest relapse rates have been described in reports with relatively short mean observation periods (<3 years), whereas in those with longer follow-up the relapse rates increase. Most of the relapses occur within 5-6 years, suggesting that follow-up is required for at least 5 years after surgery. Risk factors for relapse include the presence of squamous metaplasia in the cyst wall, cyst size and the presence of inflammation. Long-term sufficiently powered studies aiming to clarify the natural history of asymptomatic RCCs and of those relapsing postoperatively are required.