Jonathan S. Hott

Intraoperative Iso-C C-Arm Navigation in Craniospinal Surgery: The First 60 Cases

OBJECTIVE:The intraoperative Iso-C C-arm (Siremobil Iso-C 3D; Siemens Medical Solutions, Erlangen, Germany) provides a unique ability to acquire and view multi-planar three-dimensional images of intraoperative anatomy. Registration for intraoperative surgical navigation may be automated, thus simplifying the operative workflow. METHODS:Iso-C C-arm intraoperative fluoroscopy acquires 100 images, each of which must be 1.8 degrees in a circumferential fashion about an “isocentric” point in space. The system generates a high-resolution isotropic three-dimensional data set that is available immediately after the 90-second C-arm rotation. The data set is ported to the image-guided workstation, registration is immediate and automated, and the surgeon can navigate with millimetric accuracy. The authors prospectively examined data from the initial 60 patients examined with the Iso-C, among whom were cases of anterior and posterior spinal instrumentation from the occiput to the sacrum. Percutaneous and minimally invasive spinal and cranial procedures were also included. RESULTS:Automated registration for image-guided navigation was attainable for anterior and posterior cases from the cranial base and entire spine. In most cases, intraoperative postprocedural imaging with the Iso-C mitigated the need for postoperative imaging. CONCLUSION:Intraoperative Iso-C three-dimensional scanning allows real-time feedback during cranial base and spinal surgery and during procedures involving instrumentation. In most cases, it obviates the need for postoperative computed tomography. Its usefulness is in its simplicity, and it can be easily adapted to the operating room workflow. When coupled with intraoperative navigation, this new technology facilitates complex neurosurgical procedures by improving the accuracy, safety, and time of surgery.

Intraoperative Iso-C C-arm Navigation in Cervical Spinal Surgery : Review of the First 52 Cases

Study Design. Fifty-two study participants underwent cervical spine surgery using intraoperative Iso-C imaging with or without spinal navigation. Objectives. To evaluate prospectively the feasibility, advantages, limitations, and applications of Iso-C in cervical spine surgery. Summary of Background Data. Existing stereotactic spinal navigational systems images must be acquired before surgery and typically require cumbersome point-to-point registration. Intraoperative computed tomography (CT) and magnetic resonance imaging (MRI) provide real-time information but can restrict access to the patient, preclude the use of traditional operating room tables, and are time-consuming. The Iso-C allows quick, CT-quality, real-time data acquisition without restricting access to the patient. The data acquired can be automatically transferred to navigational systems with the immediate ability to navigate for anterior or posterior cervical spine procedures. Methods. High-resolution isotropic three-dimensional data sets were acquired using the Iso-C intraoperative fluoroscopy in 52 cervical spine cases. In 30 cases, the data were imported automatically to the StealthStation Treon to support neuronavigation. In 22 cases, a postprocedural intraoperative CT was obtained with the Iso-C primarily to assess the extent of osseous decompression and/or the accuracy of implants or instrumentation. In most cases, a postoperative high-resolution CT image was obtained and compared with the Iso-C data. Results. Successful automated registration suitable for navigation was attained for all anterior and posterior cervical spinal cases. The postprocedural intraoperative Iso-C data were 100% concordant with those of postoperative high-resolution CT as determined by a blinded neuroradiologist. Conclusions. Iso-C intraoperative fluoroscopy is an accurate and rapid way to perform CT-quality image-guided navigation in cervical spinal surgery. In most cases, it obviates the need for postoperative imaging.

Functional Magnetic Resonance Imaging and Optical Imaging for Dominant-hemisphere Perisylvian Arteriovenous Malformations

OBJECTIVE:In this study, we developed an a priori system to stratify surgical intervention of perisylvian arteriovenous malformations (AVMs) in 20 patients. We stratified the patients into three categories based on preoperative functional magnetic resonance imaging (fMRI) language activation pattern and relative location of the AVM. METHODS:In Group I (minimal risk), the AVM was at least one gyrus removed from language activation, and patients subsequently underwent asleep resection. In Group II (high risk), the AVM and language activation were intimately associated. Because the risk of postoperative language deficit was high, these patients were then referred to radiosurgery. In Group III (indeterminate risk), the AVM and language were adjacent to each other. The risk of language deficit could not be predicted on the basis of the fMRI alone. These patients underwent awake craniotomy with electrocortical stimulation mapping and optical imaging of intrinsic signals for language mapping. RESULTS:All patients from Group I (minimal risk) underwent asleep resection without deficit. All Group II (high-risk) patients tolerated radiosurgery without complication. In Group III (indeterminate risk), three patients underwent successful resection, whereas two underwent aborted resection after intracranial mapping. CONCLUSION:We advocate the use of fMRI to assist in the preoperative determination of operability by asleep versus awake craniotomy versus radiosurgery referral. In addition, we advocate the use of all three functional mapping (fMRI, electrocortical stimulation mapping, and optical imaging of intrinsic signals) techniques to clarify the eloquence score of the Spetzler-Martin system before definitive treatment (anesthetized resection versus radiosurgery versus intraoperative resection versus intraoperative closure and radiosurgery referral).

Cavernous Malformation of the Trigeminal Nerve Manifesting with Trigeminal Neuralgia: Case Report

OBJECTIVE AND IMPORTANCE:We describe a patient with a cavernous malformation within the trigeminal nerve at the nerve root entry zone who presented with trigeminal neuralgia. CLINICAL PRESENTATION:A 52-year-old woman sought treatment after experiencing dizziness and lancinating left facial pain for almost a year. Neurological examination revealed diminished sensation in the distribution of the trigeminal nerve on the left. Magnetic resonance imaging demonstrated a minimally enhancing lesion affecting the trigeminal nerve. INTERVENTION:The patient underwent a retrosigmoid craniotomy. At the nerve root entry zone, the trigeminal nerve was edematous with hemosiderin staining. The lesion, which was resected with microsurgical technique, had the appearance of a cavernous malformation on gross and histological examination. The patients pain improved significantly after resection. CONCLUSION:Cavernous malformations can afflict the trigeminal nerve and cause trigeminal neuralgia. Microsurgical excision can be performed safely and is associated with improvement in symptoms.

Intramedullary histoplasmosis spinal cord abscess in a nonendemic region: case report and review of the literature.

An immunocompetent patient from a nonendemic region developed a rare intramedullary thoracic histoplasmoma. A native Arizonan, with no history of travel to endemic regions, received 3 months of itraconazole for confirmed gastrointestinal histoplasmosis at an outside institution. Two years later she experienced the rapid onset of paraplegia and lost bowel and bladder function. Magnetic resonance imaging demonstrated a ring-enhancing intramedullary lesion at T2 and signal abnormality from C2 to T5. Emergent T2-T3 laminectomy was performed with ultrasonographically guided intradural exploration and midline myelotomy. The intramedullary abscess was drained. She was nonambulatory, but motor function was partially restored. An Ommaya reservoir was later placed to deliver amphotericin and a new antifungal agent, voriconazole. Magnetic resonance imaging confirmed that the infection had resolved. Intramedullary spinal histoplasmoma is a rare manifestation of disseminated histoplasmosis, particularly in nonendemic regions. Surgery for focal mass lesions and aggressive antifungal chemotherapy are the optimal treatment. Newer central nervous system-penetrating antibiotics show promise in refractory cases.

Thoracoscopic Placement of Dual-rod Instrumentation in Thoracic Spinal Trauma

OBJECTIVE AND IMPORTANCE:Traditionally, thoracic fractures that require anterior stabilization are treated through an open thoracotomy approach. Thoracoscopic instrumentation avoids many of the complications associated with an open thoracotomy but is technically challenging. We report the first cases of dual-rod internal fixation systems placed thoracoscopically for thoracic spinal trauma. CLINICAL PRESENTATION:Two male patients sustained midthoracic spinal trauma falling from motorcycles in separate incidents. Both injuries led to unstable spinal columns, but the patients had no neurological deficits and had minimal spinal cord compression. One patient had a complex spiral fracture from T6 to T8; the other had T7 burst and T8 compression fractures. Based on the complex morphological features of the patients’ fractures, anterior internal fixation was the treatment of choice for both. The two available options for an anterior stabilization were open thoracotomy and thoracoscopic instrumentation. Because extensive decompression was unnecessary, a thoracoscopic approach was used. INTERVENTION:A dual-rod internal fixation system (Medtronic Sofamor Danek, Inc., Memphis, TN) was placed with two screws each in the T6 and T9 vertebral bodies of each patient. Thoracoscopy was used for direct visualization of the operative site with fluoroscopic guidance for screw placement. Surgery was completed without complications, and both patients did well afterward. Upright and supine x-rays demonstrated that the constructs were stable at 10 weeks and 6 months, respectively. CONCLUSION:Thoracoscopic instrumentation offers the advantages of a minimally invasive approach but is technically challenging. The characteristics of dual-rod fixation systems (small-profile components and step-wise insertion) provide the best biomechanical profile and facilitate thoracoscopic instrumentation.

Sinonasal leiomyosarcoma: review of literature and case report.

Objectives/Hypothesis: To determine prognosis of primary sinonasal leiomyosarcomas after treatment.

A new table-fixed retractor for anterior odontoid screw fixation

The authors describe a unique retraction device adapted for anterior odontoid screw placement. A rigidly fixed tubular retractor system obviates the need for dissecting the longus colli muscles as well as for excessive retraction of the trachea, esophagus, and recurrent laryngeal nerve. The proper trajectory for screw placement can be determined by fine manipulation of the retractor as determined by biplanar fluoroscopy. The retractor is then rigidly fixed in position. The tubular corridor permits the odontoid screw to be placed in the usual fashion.