Extended transoral approaches: surgical technique and analysis.
ABSTRACT The transoral approach provides the most direct exposure to extradural lesions of the ventral craniovertebral junction. Lesions that extend beyond the exposure provided by the standard transoral approach require an extended transoral modification. The exposure can be expanded in the sagittal and axial planes by adding mandibulotomy, mandibuloglossotomy, palatotomy, and transmaxillary approaches to the standard transoral approach. Extended transoral approaches increase the surgical complexity and the risk of cosmetic and functional complications. Until recently, selection of an extended approach has been arbitrary and dependent on the surgeon's familiarity with the surgical approach.
We review the literature of extended transoral approaches and analyze the different modifications in terms of the technical aspects, added exposure, and complications.
Classic approaches and recently published morphometric studies that objectively document the gain in exposure provided by several modifications were analyzed and tabulated to outline the limits of exposure and risk of complications associated with the various modifications.
Transmaxillary approaches expand the exposure to include the sphenoid sinus and upper lateral clivus. To expand the exposure more inferiorly to C4-C5, mandibulotomy or mandibuloglossotomy can be applied. Mandibuloglossotomy increases the rostral exposure as well to the upper third of the clivus. Palatotomy increases rostral exposure without requiring a facial incision or perioperative tracheostomy, but is associated with a significant risk of velopharyngeal insufficiency.
Surgical decisions can be based on comprehensive preoperative evaluation of anatomy, pathology, and radiographic studies to maximize exposure while minimizing complications.
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ABSTRACT: BACKGROUND:: The endoscopic endonasal approach (EEA) has developed as an emerging surgical corridor to the craniovertebral junction (CVJ). In addition to understanding its indications and surgical anatomy, the ability to predict its inferior limit is vital for optimal surgical planning. OBJECTIVE:: To develop a method that accurately predicts the inferior limit of the EEA on the CVJ radiologically and to compare this to other currently used methods. METHODS:: Pre-dissection CT scans of nine cadaver heads were used to delineate a novel line, the naso-axial line (NAxL), to predict the inferior EEA limit on the upper cervical spine. A previously described method using the nasopalatine line (NPL or Kassam line) was also employed. On CT scans obtained following dissection of the EEA, the predicted inferior limits were compared to the actual extent of dissection. RESULTS:: The post-dissection inferior EEA limit ranged from the dens tip to upper half of the C2 body, which matched the limit predicted by NAxL, with no statistically significant difference between them. In contrast to the NAxL, the NPL predicted a significantly lower EEA limit (P<0.001), ranging from the lower half of the C2 body to the superior endplate of C3. CONCLUSION:: The novel NAxL more accurately predicts the inferior limit of the EEA than the NPL. This method, which can be easily used on preoperative sagittal scans, accounts for variations in patients' anatomy and can aid surgeons in the assessment of the EEA to address caudal CVJ pathology.Neurosurgery 07/2012; DOI:10.1227/NEU.0b013e318266e488 · 3.03 Impact Factor
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ABSTRACT: The transoral transpharyngeal surgical approach is a recognized technique for management of ventral lesions at the clivus and upper cervical spine. This report examines the use of neuronavigation and intraoperative magnetic resonance imaging as surgical adjuncts for lesions in this region. A retrospective review of patients undergoing transoral transpharyngeal surgery in the intraoperative magnetic resonance imaging (iMRI) unit from 1997 to present was performed. Preoperative demographic data, clinical history, physical examination, and imaging studies were reviewed. Data were collected on surgical approach, pathology, postoperative management, and adverse events. Twenty patients underwent resection of ventral lesions at the craniovertebral junction through a transoral approach in the iMRI suite. Mean age at time of surgery was 50 years. A variety of pathologies were identified including neoplasms (n=7), congenital anomalies (n=7), and degenerative disease (n=6). Intraoperative imaging and neuronavigation allowed for tailoring of the surgical approach in each of our patients: 11 patients underwent transoral surgery without a palatal split or mandibulotomy; 9 patients underwent a palatal split and of these, 5 required a mandibulotomy. Interdissection images allowed for immediate confirmation of gross total resection in all cases. Postoperatively, patients were managed in the intensive care unit for an average of 7 days. Ninety-two percent of patients had neurological improvement at a mean of 1.8 years of follow-up (range 0.4-6 years). Two patients died from tumor progression and one died from renal failure. Intraoperative MRI and neuronavigation are valuable adjuncts that allow selective surgical exposure and confirmation of surgical objectives within the narrow surgical corridor provided by a transoral approach to the craniovertebral junction.World Neurosurgery 11/2011; 78(1-2):164-9. DOI:10.1016/j.wneu.2011.09.020 · 2.42 Impact Factor
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ABSTRACT: BACKGROUND: The proatlas is derived from the fourth occipital sclerotome in human embryos. It usually fuses with the three upper occipital sclerotomes to form the occipital bone. However, this does not always occur. Manifestations of a partial proatlas structure may persist due to failure of fusion. CLINICAL CONSIDERATIONS: These embryological remnants can induce several symptoms in humans, ranging from mild to severe. On occasion, this structure can go unnoticed until a precipitating traumatic event results in symptoms. Proatlas segmentation abnormalities form bony masses at C1 and the foramen magnum. A number of surgical procedures have been devised to rectify the resulting neural compression and vascular compromise. DISCUSSION: This paper will discuss the development of the proatlas and the resultant anomalies associated with its failure to merge with the occipital sclerotomes to form the occipital bone. In addition, some consideration of comparative anatomy and surgical techniques will be presented.Child s Nervous System 03/2012; 28(3):349-56. DOI:10.1007/s00381-012-1698-8 · 1.16 Impact Factor