Practical and technical aspects of trans-sphenoidal surgery.

Trans-sphenoidal surgery was first described more than a century ago. Today, this approach occupies a crucial place in the armamentarium of the neurosurgeon for the management of sellar, suprasellar, and parasellar pathological conditions. Over the years, the procedure has witnessed multiple modifications, benefitting from technological advances and from innovative ideas of pioneering neurosurgeons and otolaryngologists. The introduction of the microscope and then the endoscope allowed progressive improvement of visualization, illumination, and magnification in this restricted surgical corridor. With enhanced knowledge and understanding of the surgical anatomy of the skull base, the application of extended transsphenoidal approaches became possible, thus widening significantly the anatomical area that can be reached through this approach. In addition, the continuous improvement in imaging, image guidance, and microinstruments allowed better planning and precision during surgery. In sum, thanks to recent technological advance, trans-sphenoidal surgery can now be applied to a large area of the skull base and for a wide range of pathological conditions. With growing experience, the procedure is performed with enhanced safety and greater efficacy. In this paper, we review the historical evolution of trans-sphenoidal surgery and describe the modern applications and modifications of the procedure.

Staged use of the transsphenoidal approach to resect superior third ventricular craniopharyngiomas.

INTRODUCTION: Craniopharyngiomas are benign tumors, usually originating from the infundibulum or tuber cinereum. Their surgical treatment is challenging because of their relationship to neural and vascular structures. Large craniopharyngiomas that invade the upper third of the third ventricle are a common reason for patients to need a second operation to accomplish a gross total resection. Transsphenoidal approaches are being increasingly used in the treatment of craniopharyngiomas. Large craniopharyngiomas involving the superior third ventricle are most commonly resected through a staged approach, often involving a transcortical or interhemispheric route. CASE REPORT: The authors describe the use of an extended transsphenoidal approach as a second-stage operation to resect the intraventricular component of a large craniopharyngioma in an illustrative case. CONCLUSION: The authors find this to be an excellent indication for an endoscopic extended transsphenoidal approach in selected cases.

Spontaneous recanalization of the internal carotid artery resulting in thromboembolic occlusion of the ipsilateral ophthalmic artery and visual loss.

We report a 54-year-old man who suffered a stroke from a complete right internal carotid artery (ICA) occlusion. Two months later, he presented with right eye blindness. Imaging demonstrated 50% recanalization of his right ICA. He underwent a right carotid endarterectomy to prevent contralateral stroke from emboli through a patent anterior communicating artery. Recanalization of a completely occluded proximal ICA due to atherosclerotic disease has been reported but is rare, but such patients emphasize the importance of follow-up vascular studies.

The use of the Olympus EndoArm for spinal and skull-based transsphenoidal neurosurgery.

Minimally invasive surgical techniques have evolved to reduce soft-tissue injury associated with open surgical techniques. The use of endoscopic visualization allows the exposure of deep structures and provides a mechanism to perform all the components of an open surgical procedure through small portals, thus satisfying a basic requirement of minimally invasive surgical procedures. Surgeons in the field of skull-base and spine surgery are now taking advantage of the benefits of such endoscopes. The pneumatically powered EndoArm endoscopic holder has been used extensively in both cranial and spinal neurosurgical cases at the University of Utah. These cases include minimally invasive cervical and lumbar decompression procedures, as well as more recently the resection of larger and more extensive pituitary tumors. In this paper, the multiple advantages of the Olympus EndoArm endoscopic holder are described in detail. As more surgeons gain experience with endoscopes in skull-base surgery, the hope is that operative times will be shorter and more extensive surgical resections will be possible with less patient morbidity.

Hypertrophic olivary degeneration after surgical removal of cavernous malformations of the brain stem: report of four cases and review of the literature.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a pathological phenomenon that occurs after injury to the dentato-olivary pathway. Its hallmarks include hypertrophy of the olive with increased T2 signal intensity on magnetic resonance imaging, and it often manifests with palatal tremor and oscillopsia clinically. METHOD: We report the cases of four patients who developed delayed HOD after surgical resection of pontine lesions. FINDINGS: We discuss the anatomical and pathological details of this disease and review the few other reported cases of HOD after resection of lesions within the brainstem. CONCLUSIONS: HOD should be recognized as a possible complication of surgery within the brainstem and must be diagnosed promptly so that patients can be appropriately counseled and symptoms can be treated.

Radiographic features of tumefactive giant cavernous angiomas.

BACKGROUND: Giant cavernous angiomas (GCAs) are very rare, and imaging features of GCAs can be very different from those of typical cavernous angiomas (CAs), making them a diagnostic challenge. The purpose of the study was to evaluate the radiographic features of GCAs, with an emphasis on the differentiating features from neoplastic lesions. METHODS: The neuroradiological findings of 18 patients who harbored a histologically verified GCA (CA of 4 cm or larger) were reviewed retrospectively. The magnetic resonance imaging (MRI) appearance, enhancement pattern, presence of edema or mass effect, size, and location of each lesion were recorded. When available, pertinent clinical information, including age, sex, and mode of presentation, was obtained. FINDINGS: Seizures, neurologic deficits, hemorrhage, and hydrocephalus were the most common presenting symptoms. The lesions were hyperdense and nonenhancing on computed tomography with frequent calcifications. On MRI, the lesions most commonly had a multicystic appearance, representing blood of various ages, and multiple complete hemosiderin rings. GCAs can present in any location with associating edema and mass effect, giving them a tumefactive appearance. No developmental venous anomaly was observed with any lesion. CONCLUSIONS: Most GCAs in our series presented as multicystic lesions with complete hemosiderin rings on MRI, giving a "bubbles of blood" appearance. Although this characteristic feature is helpful in the diagnosis of many cases of GCAs, the correct diagnosis in the remaining cases may not be apparent until histopathological evaluation of the specimen is made.

Recurrent infrasellar clival craniopharyngioma.

The patient is a 44-year-old man who underwent resection of a posterior nasopharynx tumor 12 years earlier via left lateral rhinotomy approach. The final pathological analysis indicated the tumor was a craniopharyngioma, and the patient subsequently underwent focal radiation. The patient returned to medical attention complaining of dysequilibrium. A neurologic exam was nonfocal. Magnetic resonance imaging revealed a clival mass, separate from the sella turcica, with imaging characteristics concerning for chordoma or primary bone tumor (Fig. 1). The lesion was resected via an endoscope-assisted endonasal transsphenoidal approach, with gross total resection achieved. Intraoperatively, the mass was noted to erode through the posterior nasopharynx, without extension superiorly into the sella or posteriorly through the clival dura (i.e., lesion was infrasellar). The final pathological results indicated the tumor was adamantinomatous craniopharyngioma.

Spontaneous regression of a cystic cavum septum pellucidum.

A persistent cavum septum pellucidum (CSP) is present in approximately 0.73% of adults, although its incidence ranges from 0.14 to 18.9% depending on the detection method. Cystic CSP is even rarer. A cyst causing mass within the CSP can obstruct the intraventricular foramen, leading to blockage of CSF flow and possible hydrocephalus, often justifying surgical intervention. We describe spontaneous decompression of a cystic CSP in a 36-year-old man. Initial MRI showed a cystic CSP with lateral bowing of the septal walls to 1.9 cm. Follow-up MRI 15 months later demonstrated no lateral bowing, and the septal wall width was 1.0 cm. This spontaneous decompression was not explained by the one previously described case report of cystic CSP regression.

Incidental giant arachnoid granulation.

Arachnoid granulations may expand the dural sinuses or inner table of the skull. Although usually incidental, giant arachnoid granulations that are of sufficient size to fill the lumen of a dural sinus and cause local dilation or filling defects can rarely cause symptoms due to sinus obstruction leading to venous hypertension. This 31-year-old man presented with a 3-month history of progressive bifrontal headaches and a giant arachnoid granulation at the posterior superior sagittal sinus. Intrasinus pressure measurements showed no significant pressure difference across the lesion to explain the headaches, which were then treated medically. Dural sinus pressure measurement, in certain cases of giant arachnoid granulations, can be used to exclude the lesion as the cause of the patient's symptoms.

Remote cerebellar hemorrhage.

Remote cerebellar hemorrhage (RCH) is a rare but benign, self-limited complication of supratentorial craniotomies that, to the best of our knowledge, has not been described in the imaging literature. RCH can be an unexpected finding on routine postoperative imaging studies and should not be mistaken for more ominous causes of bleeding such as coagulopathy, hemorrhagic infarction, or cortical vein occlusion. Cerebellar hemorrhage in the typical setting can be identified as RCH and does not require more extensive or invasive evaluation.

Distal ventriculoperitoneal shunt failure secondary to Clostridium difficile colitis.

Distal ventriculoperitoneal shunt obstruction is typically associated with cerebrospinal fluid (CSF) infection, fluid pseudocysts, bowel obstruction, bowel perforation, or improper shunt placement in the abdomen. We describe a unique etiology for distal shunt obstruction secondary to Clostridium difficile pancolitis that occurred because of inflammation and ascites, which led to incomplete drainage and absorption of CSF. This case illustrates the importance of considering distal shunt obstruction in a patient with signs of abdominal pathology in the setting of mental status changes, and the effective treatment of this patient initially with distal catheter externalization followed by internalization of a new distal catheter after resolution of the pancolitis.

Thrombosed basilar apex aneurysm presenting as a third ventricular mass and hydrocephalus.

Aneurysms presenting as third ventricular masses are uncommon; most are giant aneurysms arising from the basilar apex. We present a case of a thrombosed basilar apex aneurysm presenting as a third ventricular mass and hydrocephalus in a 55-year-old man. The case is unique in the literature as the aneurysm was completely thrombosed and angiographically occult. The lesion was explored to verify the diagnosis and a third ventriculostomy resolved the patient's symptoms. Completely thrombosed aneurysms should be considered in the differential diagnosis of symptomatic third ventricular masses, even when angiographic studies are negative. The literature on aneurysms presenting as third ventricular masses is reviewed.

Revision of vagal nerve stimulator electrodes: technical approach.

BACKGROUND: As the number of implanted vagal nerve stimulators grows, the need for removal or revision of the devices will become more frequent. Our purpose was to demonstrate the feasibility of complete removal of the vagal nerve stimulator electrode using microsurgical technique. METHODS: . Operative databases at the University of Utah (1995 through 2002), Westchester Medical Center (1995 through 2001), and University of Arizona Health Sciences Center (1995 through 1999) were retrospectively reviewed. Patients who had undergone removal or revision of a previously placed vagal nerve stimulator electrode were identified. Patients who had a vagal nerve stimulator device removed but had the lead trimmed and incompletely removed were excluded. FINDINGS: Seven patients underwent complete removal of the lead. Microsurgical dissection allowed removal of the helical electrode from the vagus nerve without apparent physiological consequences. Four patients had a new electrode placed just proximal to the original lead site. The operative procedure required an additional 30 minutes to complete compared with initial device placement. The four patients who underwent replacement of the electrode demonstrated normal device function and lead resistance at the time of postoperative follow-up. Each experienced a return to prior stimulation response and seizure control. CONCLUSIONS: This series suggests that the electrode can be removed from the vagus nerve and repositioned without significant consequence in most cases.

Bilateral testicular enlargement and seminoma in a patient with acromegaly.

Growth hormone (GH) excess has been associated with soft tissue changes and an increase in the incidence of colonic polyps and gastrointestinal cancer. We describe a patient with endogenous GH excess caused by a pituitary tumour, resulting in acromegaly. The patient had bilateral testicular enlargement, with tumour of the right testicle. Pituitary MRI revealed a macroadenoma. After resection of the pituitary tumour, GH levels fell below 0.5 ng/ml, with acromegaly resolution. Testicular resection revealed seminoma. Following acromegaly resolution, the enlarged remaining testicle decreased in size. The implications of the testicular enlargement and seminoma in the presence of a GH-secreting tumour are discussed.

Endoscopic-assisted craniofacial resection of esthesioneuroblastoma: minimizing facial incisions--technical note and report of 3 cases.

The surgical management of esthesioneuroblastoma with anterior skull base involvement has traditionally been craniofacial resection, which combines a bifrontal craniotomy with a transfacial approach. The latter usually involves a disfiguring facial incision, mid-facial degloving, lateral rhinotomy, and/or extensive facial osteotomies, which may be cosmetically displeasing to the patient. The advent of angled endoscopes has provided excellent magnification and illumination for surgeons to remove tumors using minimally invasive techniques. The authors describe their experience with three cases of esthesioneuroblastoma, which were surgically removed using a transnasal endoscopic approach, avoiding transfacial incisions. Preoperative radiographs were reviewed and tumors were staged according to the Kadish staging system. One patient had a recurrent esthesioneuroblastoma (Kadish stage B), which was removed entirely through a transnasal endoscopic approach. Two patients had intracranial extension (Kadish stage C), which were resected with a combined approach, endoscopically from below and a bifrontal craniotomy from above, to remove intracranial disease. All patients underwent reconstruction of the anterior skull base. Esthesioneuroblastomas confined to the nasal and paranasal cavities (Kadish stage A and B) were readily accessible through the transnasal endoscopic approach. If there was significant intracranial disease (Kadish stage C), adding a bifrontal craniotomy provided excellent exposure for complete resection of involved tumor. All patients underwent complete tumor resection with negative margins. None developed a cerebrospinal fluid (CSF) leak. The endoscopic-assisted craniofacial approach for the surgical management of esthesioneuroblastomas provides excellent exposure, adequate visualization, and the cosmetic benefit of avoiding an external facial incision.

Enlargement of a vestibular schwannoma after stereotactic radiotherapy.

BACKGROUND: Radiosurgery has been increasingly advocated as a primary treatment for vestibular schwannoma (VS), and recently fractionation of the dose has been proposed as a method to decrease the risk of radiation injury when treating larger tumors. METHOD: The authors describe a 48-year-old woman who presented with right-sided hearing loss and new-onset tinnitus, with a progressive decrease in facial sensation. The diagnosis of a large right cerebellopontine angle VS was made on magnetic resonance imaging (MRI). The patient was treated with a course of fractionated stereotactic radiotherapy (SRT) (5 treatments of 4 Gy to the 90% isodose line over a 3-week period). FINDINGS: Six months after the initiation of therapy, her symptoms increased, and a repeat MRI scan demonstrated that her tumor had increased in size, producing significant brainstem compression. She then underwent complete surgical resection of the tumor, with resolution of her symptoms. INTERPRETATION: Stereotactic radiosurgery has been effective in controlling small VSs with low complication rates. Larger tumors pose a risk for increasing in size and producing symptoms from mass effect with SRT. There are at present limited data demonstrating safety and efficacy of fractionated SRT for the treatment of larger tumors.

Vertebral arterial dissection associated with Klippel-Feil syndrome in a child.

BACKGROUND: Vertebral artery dissection resulting in stroke is rare in children. We report here on a 7-year-old boy with Klippel-Feil abnormality, who presented with a pontine infarction after a supervised swimming session. METHODS: Evaluation after a second acute neurological event included a formal cerebral angiogram, which revealed a complete upper basilar artery occlusion and right vertebral arterial dissection. Cervical spine radiographs demonstrated an associated fusion of the C2 and C3 vertebrae. Anticoagulation therapy was initiated, and the neurological deficits associated with the pontine infarction resolved. Anticoagulation was discontinued after 6 months of therapy, with no recurrence of symptoms. CONCLUSION: Vertebral artery dissection may rarely be associated with Klippel-Feil abnormality in children.

Effect of absorbable topical hemostatic agents on the relaxation time of blood: an in vitro study with implications for postoperative magnetic resonance imaging.

OBJECT: Absorbable topical hemostatic agents are commonly used in neurosurgery. In this study the authors examine the longitudinal relaxation time (T1) of blood in contact with these agents over time, measured in vitro, to determine if their presence could affect the interpretation of postoperative magnetic resonance (MR) images. METHODS: Coagulated and anticoagulated blood were used, both oxygenated and deoxygenated. The effects of a collagen-based agent (Collastat) and a cellulose-based agent (Surgicel) on the pH and T1 values of blood and on those of saline (used as a control) were investigated. The T1 was measured as a function of magnetic field strength and time by using a field-cycling relaxometer. This instrument measures 1/T1, the rate of T1, from which the T, value is computed. The T1 values of blood were compared with those of hemostat-induced blood clots and with those of both gray and white matter of the brain. Signal changes on T1-weighted MR images were predicted on the basis of altered T, values in vitro. Postoperative images were visually examined for the predicted changes. With the addition of Surgicel, blood had decreased pH and significantly shortened T1 at all fields, essentially within minutes, although it affected the T1 of saline only minimally. The effect of Surgicel increasingly shortened the T1 for 4 days in oxygenated blood. Collastat had no significant effect. The presence of some paramagnetic methemoglobin in Surgicel-induced clots was demonstrated using the relaxometer at a time when diamagnetic oxyhemoglobin would be present in naturally occurring blood clots. A bright signal that could mimic residual tumor on contrast-enhanced images was predicted and confirmed on postoperative T1-weighted MR images obtained in patients in whom Surgicel lined the tumor bed. It was not present in cases in which Surgicel was not used. CONCLUSIONS: Surgicel alters the appearance of early postoperative MR images. To avoid misinterpretation, clinicians should be aware of this phenomenon.