Anand V. Germanwala

Nasoseptal flap reconstruction of high flow intraoperative cerebral spinal fluid leaks during endoscopic skull base surgery.

Background Over the past 10 years, significant anatomic, technical, and instrumentation advances have facilitated the exposure and resection of intradural lesions via a fully endoscopic expanded endonasal approach (EEA). The vascularized nasoseptal flap (based on the posterior nasoseptal artery) has become our primary endoscopic reconstructive technique. The goals of this study are to prospectively evaluate the nasoseptal flap and high-risk cerebral spinal fluid (CSF) leak variables. Methods Prospective evaluation was performed of EEA patients with intraoperative high-flow leaks (either a cistern or ventricle open to nasal cavity during tumor dissection) who underwent nasoseptal flap reconstruction. Results Seventy consecutive nasoseptal flaps for high-flow intraoperative leaks were evaluated prospectively by the primary author. Twelve risk factors were then graded at the time of the operations and correlated to CSF leak outcomes. The overall postoperative CSF leak rate was 5.7% (4/70). All four postoperative leaks were successfully managed with endoscopic repair and CSF diversion. A multivariate analysis of all 12 risk factors is detailed. Pediatric patients, large dural defects, and radiation therapy were noted to be factors in reconstructive failure. One flap death occurred in a patient with prior surgery and proton therapy, this leak was managed with a temporoparietal flap and endonasal repair. Conclusion The nasoseptal flap is an excellent anterior skull base reconstructive technique. Patients with high-flow intraoperative CSF leaks had a 94% successful reconstruction rate. Patients with skull base proton radiation therapy are at higher risk for flap failure and preparation for nonradiated tissue reconstruction should be discussed with the patient.

Brain metastases treated with radiosurgery alone: an alternative to whole brain radiotherapy?

OBJECTIVEWhole brain radiotherapy (WBRT) provides benefit for patients with brain metastases but may result in neurological toxicity for patients with extended survival times. Stereotactic radiosurgery in combination with WBRT has become an important approach, but the value of WBRT has been questioned. As an alternative to WBRT, we managed patients with stereotactic radiosurgery alone, evaluated patients’ outcomes, and assessed prognostic factors for survival and tumor control. METHODSOne hundred seventy-two patients with brain metastases were managed with radiosurgery alone. One hundred twenty-one patients were evaluable with follow-up imaging after radiosurgery. The median patient age was 60.5 years (age range, 16–86 yr). The mean marginal tumor dose and volume were 18.5 Gy (range, 11–22 Gy) and 4.4 ml (range, 0.1–24.9 ml). Eighty percent of patients had solitary tumors. RESULTSThe overall median survival time was 8 months. The median survival time in patients with no evidence of primary tumor disease or stable disease was 13 and 11 months. The local tumor control rate was 87%. At 2 years, the rate of local control, remote brain control, and total intracranial control were 75, 41, and 27%, respectively. In multivariate analysis, advanced primary tumor status (P = 0.0003), older age (P = 0.008), lower Karnofsky Performance Scale score (P = 0.01), and malignant melanoma (P = 0.005) were significant for poorer survival. The median survival time was 28 months for patients younger than 60 years of age, with Karnofsky Performance Scale score of at least 90, and whose primary tumor status showed either no evidence of disease or stable disease. Tumor volume (P = 0.02) alone was significant for local tumor control, whereas no factor affected remote or intracranial tumor control. Eleven patients developed complications, six of which were persistent. Nineteen (16.5%) of 116 patients in whom the cause of death was obtained died as a result of causes related to brain metastasis. CONCLUSIONBrain metastases were controlled well with radiosurgery alone as initial therapy. We advocate that WBRT should not be part of the initial treatment protocol for selected patients with one or two tumors with good control of their primary cancer, better Karnofsky Performance Scale score, and younger age, all of which are predictors of longer survival.

Combination kyphoplasty and spinal radiosurgery: a new treatment paradigm for pathological fractures

OBJECT Patients with symptomatic pathological compression fractures require spinal stabilization surgery for mechanical back pain control and irradiation for the underlying malignant process. The authors evaluated a treatment paradigm of closed fracture reduction and fixation involving kyphoplasty and subsequent spinal radiosurgery. METHODS Twenty-six patients (six men and 20 women, mean age 72 years) with pathological compression fractures (16 thoracic and 10 lumbar) were prospectively evaluated. Histological diagnoses included 11 lung, nine breast, four renal, one cholangiocarcioma, and one ocular melanoma. Seven lesions had received prior external-beam radiation therapy. All patients underwent kyphoplasty that involved the percutaneous transpedicular technique. Fiducial markers allowing for image guidance during CyberKnife treatment were placed, at time of the kyphoplasty, in the pedicles at adjacent levels. Patients underwent single-fraction radiosurgery (mean time after kyphoplasty 12 days) in an outpatient setting. The tumor dose was maintained at 16 to 20 Gy (mean 18 Gy) to the 80% isodose line. The treated tumor volume ranged from 12.7 to 37.1 cm3. No acute radiation-induced toxicity or new neurological deficit occurred during the follow-up period (range 11-24 months, median 16 months). Axial pain improved in 24 (92%) of 26 patients. CONCLUSIONS The combined kyphoplasty and spinal radiosurgery treatment paradigm was found to be clinically effective in patients with pathological fractures; there was no significant spinal canal compromise. In this technique two minimally invasive surgical procedures are combined to avoid the morbidity associated with open surgery while providing both immediate fracture fixation and administering a single-fraction tumoricidal radiation dose.

Hardware-Related Complications after Placement of Thalamic Deep Brain Stimulator Systems

Deep brain stimulation (DBS) has become a common therapeutic approach to patients with movement disorders. We evaluated results from two centers in a large metropolitan area where DBS systems are implanted into the thalamus for patients with tremor. Although all implanted systems led to an improvement in tremor, morbidity related to the hardware system occurred. A total of 23 hardware problems were noted in 66 patients undergoing implantation of 66 DBS systems (27% of patients). The most common problem included breakage of the electrode lead in its extracranial location, system infection, battery or connector problems, lead migration, and hemorrhage. Management was tailored to the specific hardware-related problem. Modifications in both surgical technique and hardware design should reduce the incidence of complications. Surgeons who place DBS systems should be aware of the spectrum of problems that can be associated with the device and its placement.

Endoscopic pedicled nasoseptal flap reconstruction for pediatric skull base defects

A prospective study of endoscopic expanded endonasal approaches (EEA) with nasoseptal flap reconstructions revealed anecdotal evidence of less available relative septal length in pediatric patients. Our goal is to use radioanatomic analysis of computed tomography (CT) scans to determine limitations of the nasoseptal flap in pediatric skull base reconstruction and to describe clinical outcomes after using the nasoseptal flap in six pediatric patients.

How to Choose? Endoscopic Skull Base Reconstructive Options and Limitations

As endoscopic skull base resections have advanced, appropriate reconstruction has become paramount. The reconstructive options for the skull base include both avascular and vascular grafts. We review these and provide an algorithm for endoscopic skull base reconstruction. One hundred and sixty-six skull base dural defects, reconstructed with an endonasal vascular flap, were examined. As an adjunct, avascular reconstruction techniques are discussed to illustrate all options for endonasal skull base reconstruction. Cerebrospinal fluid (CSF) leak rates are also discussed. Small CSF leaks may be successfully repaired with various avascular grafting techniques. Endoscopic endonasal approaches (EEAs) to the skull base often have larger dural defects with high-flow CSF leaks. Success rates for some EEA procedures utilizing avascular grafts approach 90%, yet in high-flow leak situations, success rates are much lower (50 to 70%). Defect location and complexity guides vascularized flap choice. When nasoseptal flaps are unavailable, anterior/sellar defects are best managed with an endoscopically harvested pericranial flap, whereas clival/posterior defects may be reconstructed with an inferior turbinate or temporoparietal flap. An endonasal skull base reconstruction algorithm was constructed and points to increased use of various vascularized reconstructions for more complex skull base defects.

Nasoseptal “Rescue” Flap: A Novel Modification of the Nasoseptal Flap Technique for Pituitary Surgery

The introduction of the pedicled nasoseptal flap (NSF) has decreased postoperative cerebrospinal fluid (CSF) leak rates from >20% to <5% during expanded endoscopic skull base surgery. The NSF must be raised at the beginning of the operation to protect the posterior pedicle during the expanded sphenoidotomy. However, in most pituitary tumor cases, an intraoperative CSF leak is not expected but at times encountered. In these cases, a “rescue” flap approach can be used, which consists of partially harvesting the most superior and posterior aspect of the flap to protect its pedicle and provide access to the sphenoid face during the approach. The rescue flap can be fully harvested at the end of the case if the resultant defect is larger than expected, or if an unexpected CSF leak develops. This technique minimized septum donor site morbidity for those patients without intraoperative CSF leaks.

Pericranial flap for endoscopic anterior skull-base reconstruction: Clinical outcomes and radioanatomic analysis of preoperative planning

BACKGROUNDOne of the major challenges of cranial base surgery is reconstruction of the dural defect and prevention of postoperative cerebrospinal fluid (CSF) fistula. The introduction of endoscopic techniques and an endonasal approach to the ventral skull base has created new challenges for reconstruction. OBJECTIVEWe have developed an endoscopic pericranial flap (PCF) for skull base reconstruction and hereby present the initial cohort of patients who had endonasal reconstruction with a PCF after endoscopic skull base resection. We also demonstrate a method to radiographically incorporate anticipated skull base defects for preoperative planning of PCF length. METHODSDural defects after endonasal skull base resection of invasive tumors were reconstructed with an onlay PCF (n = 10). We performed radiological studies to assist preoperative planning for where to make incisions while harvesting a PCF for anterior skull base, sellar, and clival defects. RESULTSEach of the 10 patients had excellent healing of their skull base and had no evidence of any postoperative cerebrospinal fluid leaks. Eight patients had radiation therapy without flap complications. Radiographic studies demonstrate that the adequate PCF length, covering defects of the anterior skull base, sellar, and clival defects are 11.31 to 12.44 cm, 14.31 to 15.57 cm, and 18.5 to 20.42 cm, respectively. CONCLUSIONThe PCF provides an option for endonasal reconstruction of cranial base defects and can be harvested endoscopically. Pre-operative radiographic evaluation may guide surgical planning. There is minimal donor site morbidity, and the flap provides enough surface area to cover the entire ventral skull base.

Hydrocephalus after aneurysmal subarachnoid hemorrhage.

Hydrocephalus is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (SAH). Its incidence is approximately 20% to 30%, and its onset can be acute, within 48 hours after SAH, or rarely chronic, occurring in a delayed fashion weeks and even months after the hemorrhage. Early recognition of its signs and symptoms and accurate interpretation of computed tomography (CT) studies are important for the management of patients with SAH. Clinically, a poor neurologic grade has the highest correlation with an increased incidence of hydrocephalus. Radiographically, the bicaudate index on CT studies has emerged as the best marker of this condition. Although further studies are needed to understand the complex pathophysiology of this condition, hydrocephalus after SAH can be treated effectively using current technology.

Beyond the nasoseptal flap: Outcomes and pearls with secondary flaps in endoscopic endonasal skull base reconstruction

Endoscopic endonasal skull base surgery defects require effective reconstruction. Although the nasoseptal flap (NSF) has become our institutions workhorse for large skull base defects with cerebrospinal fluid (CSF) leaks, situations where it is unavailable require secondary flaps. Clinical outcomes, pearls and pitfalls, and an algorithm will be presented for these secondary flaps.