Image-guided navigation and video-assisted thoracoscopic spine surgery: the second generation.

OBJECT: Video-assisted thoracoscopic surgery (VATS) has evolved for treatment of a variety of spinal disorders. Early incorporation with image-guided surgery (IGS) was challenged due to reproducibility and adaptability, limiting the procedure's acceptance. In the present study, the authors report their experience with second-generation IGS and VATS technologies for anterior thoracic minimally invasive spinal (MIS) procedures. METHODS: The surgical procedure is described in detail including operating room set-up, patient positioning (a lateral decubitus position), placement of the spinal reference frame and portal, radiographic localization, registration, surgical instruments, and the image-guided thoracoscopic discectomy. RESULTS: Combined IGS and VATS procedures were successfully performed and assisted in anatomical localization in 14 patients. The mean patient age was 59 years (range 32-73 years). Disc herniation pathology represented the most common indication for surgery (n = 8 patients); intrathoracic spinal tumors were present in 4 patients and the remaining patients had infection and ossification of the posterior longitudinal ligament. All patients required chest tube drainage postoperatively, and all but 1 patient had drainage discontinued the following day. The only complication was a seroma that was presumed to be due to steroid therapy for postoperative weakness. At the final follow-up, 11 of the patients were improved neurologically, 2 patients had baseline neurological status, and the 1 patient with postoperative weakness was able to ambulate, albeit with an assistive device. The evolution of thoracoscopic surgical procedures occurring over 20 years is presented, including their limitations. The combination of VATS and IGS technologies is discussed including their safety and the importance of 3D imaging. In cases of large open thoracotomy procedures, surgeries require difficult, extensive, and invasive access through the chest cavity; using a MIS procedure can potentially eliminate many of the complications and morbidities associated with large open procedures. The authors report their experience with thoracic spinal surgeries that involved MIS procedures and the new technologies. CONCLUSIONS: The most significant advance in IGS procedures has resulted from intraoperative CT scanning and automatic registration with the IGS workstation. Image guidance can be used in conjunction with VATS techniques for thoracic discectomy, spinal tumors, infection, and ossification of the posterior longitudinal ligament. The authors' initial experience has revealed this technique to be useful and potentially applicable to other MIS procedures.

Surgical management of primary spinal hemangiopericytomas: an institutional case series and review of the literature.

PURPOSE: Hemangiopericytoma (HPC) is a rare tumor of the central nervous system. Primary spinal occurrence of this tumor is extremely uncommon and cases involving the intramedullary spinal cord are even more rare. The purpose of this study was to explore the clinical features, surgical strategies, outcome and pathology in a consecutive series of patients treated at a single institution. METHODS: The authors performed a retrospective review of the clinicopathological characteristics of four patients with a pathological diagnosis of spinal HPC. RESULTS: Four cases with intradural as well as intra/extra-medullary components were identified. Gross total resection with no recurrence at the operative site was achieved in the majority of patients with a spinal HPC. One patient had significant recurrence and eventually, succumbed to the disease. CONCLUSION: Increased awareness of these tumors' capability to occur intradurally and intramedullarly can help surgeons accurately diagnose and choose an effective plan of care. Gross total resection of hemangiopericytomas is the mainstay of treatment and should be pursued if feasible. Histopathology is essential to the diagnosis.

Repeated transsphenoidal surgery to treat recurrent or residual pituitary adenoma.

OBJECT: In this paper the authors describe the indications for and the results and complications of repeated transsphenoidal surgery (RTSS) to treat recurrent or residual pituitary adenoma. METHODS: A retrospective review was conducted of 96 consecutive patients who underwent RTSS to treat recurrent or residual pituitary adenoma. Ninety-six patients underwent RTSS: 42 to treat a recurrent or residual pituitary mass and 54 to treat a recurrent or persistent hormone hypersecretion. There was no case of perioperative death and there was a 1% incidence of major complications. Postoperative endocrinological deficiencies were uncommon unless planned total hypophysectomy was performed to treat Cushing disease. Clinical remission occurred in 93% of patients undergoing RTSS to treat a tumor mass, and 15% of patients initially experienced remission only to face a relapse after a mean of 32 months. Endocrinological remission occurred in 57% of patients undergoing RTSS to treat hormone hypersecretion; most of these patients had Cushing disease. Thirty-five percent of patients with an initial endocrinological remission experienced a relapse of their symptoms after a mean of 31 months (thus, 37% of patients achieved sustained endocrinological remission). We failed to identify factors that accurately predicted initial symptom remission or delayed relapse following RTSS. Ten patients in our series eventually underwent a third transsphenoidal surgery without major complications. CONCLUSIONS: Repeated transsphenoidal surgery is a more effective treatment for recurrent or residual mass than it is for hormone hypersecretion and has acceptable rates of morbidity and mortality. If hypophysectomy is not performed, endocrinological deficiencies are unlikely following RTSS.

Giant prolactinomas: clinical management and long-term follow up.

OBJECT: Giant prolactinomas are rare tumors whose treatment and outcome has only been addressed in isolated case reports. The authors document the long-term follow-up findings and clinical outcome in a group of patients with giant prolactinomas. METHODS: This study is a retrospective chart and clinical review of more than 2000 cases of pituitary tumors treated at the authors' institution, of which 10 met the criteria for inclusion (prolactin level > 1000 ng/ml, diameter > 4 cm on neuroimaging studies, and clinical signs of hyperprolactinemia/mass effect). The average follow-up duration was 6.7 years after initial treatment with either bromocriptine or transsphenoidal resection. In more than 90% of the patients in this series the disease was controlled by medical treatment with bromocriptine alone; the other 10% required early surgery via transsphenoidal resection. All patients had improvement in visual symptoms. All tumors had extrasellar components, five of which exhibited frank invasion of the cavernous sinus. Tumor volume on magnetic resonance imaging was decreased on average by 69%; this occurred at a faster rate and in larger amounts when treated with bromocriptine than has been reported in the literature for macroprolactinomas. CONCLUSIONS: According to long-term follow-up findings, giant prolactinomas are exquisitely responsive to dopamine agonist therapy. In giant prolactinomas the prolactin level does not correlate with size. The main indication for early surgery is intratumoral hematoma, whereas our main indications for late surgery are cerebrospinal fluid leakage caused by medical treatment, or an increasing prolactin level despite medical therapy. Checking prolactin levels in suspicious sellar and/or suprasellar lesions may be diagnostic and prevent unnecessary surgery.

Surgery for Rathke cleft cysts: technical considerations and outcomes.

OBJECT: The aim of this study was to identify the optimal surgical goals and techniques for managing symptomatic Rathke cleft cysts (RCCs). METHODS: The authors conducted a retrospective study of 62 consecutive patients who had undergone surgery for RCCs. Postoperative follow up was a mean of 28 months. Fifty-six patients underwent transsphenoidal cyst decompression and biopsy procedures, and six underwent cyst wall resection. Postoperatively, symptoms improved in 91% of patients with headaches and 92% of patients with visual deficits. Decompression and biopsy were associated with a 10% incidence of new anterior pituitary hormone deficiencies and a 6% incidence of new permanent diabetes insipidus; the incidence of new hormone deficiencies was significantly higher in the few patients who had undergone cyst wall resection. The incidence of relapse, defined as cyst regrowth with either recurrent symptoms or chiasmal compression, was 16%. Resection of the cyst wall was associated with a trend toward a decreased risk of relapse. Sellar packing, sellar floor reconstruction, and irrigation with absolute ethanol did not affect the likelihood of relapse. Squamous metaplasia and inflammation increased the risk of relapse. Residual cyst demonstrated on postoperative magnetic resonance imaging was associated with an increased risk of subsequent asymptomatic cyst regrowth. Seven patients (11%) underwent repeated operation with symptomatic improvement and minimal morbidity; only one patient relapsed following a second surgery. CONCLUSIONS: Decompression and biopsy procedures in the treatment of RCCs lead to improvement in signs and symptoms, with low morbidity rates. Repeated operations will be required in as many as 16% of patients but are also associated with symptomatic improvement, low morbidity, and durable remission. Decompression and biopsy may represent the optimal surgical management of RCC.

Granular cell tumor of the pituitary fossa.

Although granular cell tumors are relatively common in the head and neck, symptomatic granular cell tumors of the neurohypophysis are extremely rare. Ophthalmologic symptoms are most common, followed by endocrinologic manifestations. We report a case of a granular cell tumor of the pituitary fossa that was surgically treated. The clinical manifestations, radiographic appearance, and surgical management of granular cell tumors of the pituitary fossa are reviewed, as well as the unique histopathology and electron microscopy of this uncommon neoplasm.

Endoscopy in neuro-otologic surgery.

Endoscopy offers several distinct advantages over the operating microscope during neuro-otologic surgery that make it an excellent adjunctive tool to the microscope or independent modality during cranial base surgery. The high magnification gives excellent definition of perforating blood vessels, cranial nerves, and neural structures, which in many cases is superior to that achieved with the microscope. Furthermore, the use of angled or flexible endoscopes allows one to look around corners and behind anatomic structures blocking the view seen via a 0 degree microscope. Endoscopy also has the theoretical advantage that a less invasive operative procedure is required, which should reduce the operative morbidity. Several notable disadvantages of endoscopy include the problems associated with blood soiling the endoscope, making visualization difficult or impossible, the lack of readily available instrumentation designed specifically for endoscopic neuro-otology, and the poor overview of the operative field. This last point is an important one because the endoscope is placed adjacent to the lesion and does not allow one to look backward to prevent [figure: see text] injury to structures next to the shaft of the telescope. Furthermore, the surgeon must be cognizant of potential thermal injury to structures caused by the heat generated by the light source. The present endoscopic technology limits the image that the surgeon sees to two dimensions, which results in certain unique problems when operating in a three-dimensional milieu. Because of this, there is a steep learning curve to acquire endoscopic dexterity and three-dimensional orientation. Finally, bimanual operation requires the use of an articulated endoscope holder or the commitment of the co-surgeon to hold the endoscope. One of the limitations of the operative microscope is that the angle of view is determined by the distance of the lens to the skull, retractor, or obstructing tissue, which is a function of the lens focal length; the longer the focal length, the narrower the viewing angle. During most microsurgical procedures, the focal distance varies between 200 and 400 mm. Using a previous analogy, if one looks through a door's keyhole at close range, nearly the entire room on the opposite side of the door can be seen, although nothing can be seen when the hole is viewed from a long distance. This is similar to what happens when using the endoscope with focal lengths ranging from 5 to 20 mm: a wider angle of view can be achieved. Based on their, experience the authors believe that endoscopes can be used safely during neuro-otologic surgery. As an adjunct to or substitution for the operative microscope, this modality does improve visualization of bony, neural, and vascular structures while minimizing cerebellar retraction.

Image-guided thoracoscopic resection of thoracic dumbbell nerve sheath tumors.

BACKGROUND: Surgical removal of dumbbell nerve sheath tumors (NSTs) remains challenging because these neoplasms occupy ≥ 2 spinal and extraspinal spaces. The presence of intraspinal extension, tumor dimension, and/or its location within the thoracic cavity have previously made the resection of these types of neoplasms difficult. OBJECTIVE: To describe the feasibility of performing minimally invasive thoracoscopic surgery, as facilitated by an image guidance system (IGS), to achieve gross total resection of select dumbbell NSTs located in the thoracic spine. METHODS: The 3 cases presented here contained small intraspinal or foraminal components. Preoperative symptoms included Horner syndrome and back and chest wall pain. We used IGS to help guide the complete thoracoscopic resection of select dumbbell NSTs, consisting of extradural, intraforaminal, and paravertebral tumor components, which previously would have been challenging with only a thoracoscopic approach. RESULTS: IGS provided continuous intraoperative anatomic orientation to achieve gross total resection in all 3 cases. All surgical and postsurgical outcomes were satisfactory; preoperative symptoms improved or resolved; and no adverse events were observed. CONCLUSION: Thoracic dumbbell NSTs that have small intraspinal or foraminal components could be resected thoracoscopically when facilitated by IGS. Image-guided thoracoscopic resection of such dumbbell tumors may not only improve the precision of resection, reduce recurrence, and avoid the need for spinal reconstruction but also obviate the need for more invasive or simultaneous posterior procedures. The IGS enhances the accuracy and safety of 2-dimensional thoracoscopic surgery and may reduce its learning curve.

Image-guided thoracoscopic spinal surgery: a merging of 2 technologies.

STUDY DESIGN: Retrospective clinical and intraoperative navigational data review. OBJECTIVE: To evaluate quantitatively the application of frameless stereotactic image guidance in thoracoscopic discectomy procedures. SUMMARY OF BACKGROUND DATA: Thoracoscopic spinal surgery has technical and anatomic challenges that result in difficult orientation with a 2-dimensional imaging procedure in a complex 3-dimensional structure. METHODS: There were 16 patients who underwent image-guided thoracoscopic discectomy procedures that combine these 2 technologies. Accuracy was determined by the registration (calculated) error and actual navigation (intraoperative) error. The clinical outcomes and complications were reviewed. RESULTS: Accuracy determined by registration (calculated) and navigation (intraoperative) was 1.7 and 1.2 mm, respectively. The additional time required for the image guidance portion of the procedure was countered by the efficiency of the remaining procedure. Clinical outcomes and complication were comparable with previous experience. CONCLUSIONS: Image-guided thoracoscopic spinal surgery can provide 3-dimensional orientation to a 2-dimensional imaging procedure that ultimately improves accuracy, efficiency, and safety. Future developments in combining guidance technology with standard surgical procedures will likely continue.