Assessing the Structural Footprint of Minimally Invasive Brain Cannulation on Cerebral White Matter: A Cadaveric Model.

BACKGROUND: All brain surgery requires some degree of iatrogenic trauma to healthy tissue. Minimally invasive approaches to brain tumors offer the potential of decreasing this trauma compared with conventional approaches. However, there are no validated radiologic models to examine axonal damage after minimally invasive entry into the brain. OBJECTIVE: To present a cadaveric model of brain cannulation using fractional anisotropy measurements obtained from diffusion tensor magnetic resonance imaging (MRI). Two different methods of access are compared. METHODS: Freshly harvested unfixed cadaveric brains were cannulated using both direct and indirect (i.e., dilation followed by cannulation) methods. Specimens were subjected to 68-direction diffusion tensor imaging scans and proton-density imaging. Fractional anisotropy (FA) data from a region of interest surrounding the entry zone was extracted from scans using imaging software and analyzed. RESULTS: FA values were significantly higher following indirect cannulation (less invasive method) than they were following direct cannulation. FA values for undisturbed brain were significantly higher than in either of the cannulated groups, suggesting an inverse relationship between FA values and brain injury. CONCLUSION: Axonal damage following brain cannulation can potentially be evaluated by FA analysis in a cadaveric model. These data may lead to an MRI-based model of iatrogenic brain injury following tumor surgery. Future studies will focus on histologic analysis and clinical validation in live tissues.

Endoscopic port surgery for resection of lesions of the cerebellar peduncles: technical note.

BACKGROUND: Mass lesions of the inferior, middle, and superior cerebellar peduncles (cerebellar peduncle complex [CPC]) present numerous surgical pitfalls when resection or debulking is warranted. Success has been achieved through multiple approaches, but complications can be severe. OBJECTIVE: To report the surgical technique for and clinical results of the treatment of lesions in the CPC with an endoscopic port via a lateral transcerebellar corridor. METHODS: Three patients underwent resection of intrinsic lesions of the CPC via a lateral transcerebellar approach with an endoscopic port. Deployment of the port was performed with frameless image-guided placement into the area of interest. Resection was performed using bimanual microsurgical technique under parallel endoscopic visualization. RESULTS: Three patients 43, 27, and 13 years of age underwent successful resection of lesion in the CPC. Histopathological diagnosis consisted of cavernous malformation, glioblastoma multiforme, and a juvenile pilocytic astrocytoma. All had complete gross total resection except for the patient with a high-grade glioma. Clinically, all had excellent outcomes, with 1 patient suffering postoperative facial palsy after resection of her high-grade glioma. CONCLUSION: The lateral transcerebellar approach to the CPC with an endoscopic port may be a feasible alternative to standard microsurgical resection in such difficult cases. Careful patient selection is critical to identify those who may be suitable for endoscopic port surgery on the basis of clinical, radiographic, and anatomical considerations.

Stereotactically guided endoscopic port surgery for intraventricular tumor and colloid cyst resection.

BACKGROUND: Intraventricular lesions are challenging entities that may be difficult to resect completely and safely, especially larger lesions with high vascularity or firm consistency. OBJECTIVE: To assess the results of stereotactically guided endoscopic port (SEP) surgery for resection of colloid cysts and intraventricular tumors. METHODS: The authors developed a minimally invasive microsurgical technique for intraventricular surgery using parallel endoscopy to visualize the lesion. Surgical resection was performed via an 11.5-mm transparent conduit (Neuroendoport) deployed under stereotactic guidance. Forty-seven consecutive cases were performed, and all had a minimum 1-year follow-up to assess the efficacy of the technique. RESULTS: For colloid cysts, gross total resection was achieved in 31 (96.9%) of the 32 cases. The transient neurologic morbidity rate was 9.4%; no permanent neurologic morbidity occurred. For intraventricular tumors, gross or near total resection was achieved in 80% of cases. The transient neurological morbidity rate was 6.7%, and no permanent neurological morbidity occurred. CONCLUSION: SEP surgery for colloid cysts and intraventricular tumors proved to be a safe and effective alternative to conventional microsurgical resection. This technique was not limited by the vascularity, friability, or size of any of the lesions.

Intracranial angiomatoid fibrous histiocytoma presenting as recurrent multifocal intraparenchymal hemorrhage.

Angiomatoid fibrous histiocytoma (AFH) is a rare soft-tissue neoplasm that most commonly appears in the limbs, typically affecting children and young adults. The tumor has a propensity for local recurrence and recurrent hemorrhage but rarely for remote metastasis. To date, only 2 reports have documented an intracranial occurrence of the tumor (1 of which was believed to be metastatic disease). This is the second report of primary intracranial AFH. Additionally, hemorrhage from an intracranial AFH lesion has yet to be reported, and little is known about the radiographic characteristics and biological behavior of these lesions. In this report, the authors describe the case of a patient with recurrent hemorrhage due to primary multifocal intracranial AFH. Initially misdiagnosed as a cavernous malformation and then an unusual meningioma, the tumor was finally correctly identified when there was a large enough intact resection specimen to reveal the characteristic histological pattern. The diagnosis was confirmed using immunohistochemical and molecular studies.

Minimally invasive endoscopic-assisted posterior thoracic sympathectomy.

Palmar hyperhidrosis is a disorder of the autonomic nervous system characterized by excessive perspiration of the palms, but may involve other body parts as well. Traditional posterior approaches have been performed less often in favor of less invasive thoracoscopic sympathectomies, which have a high success rate with low associated morbidity. However, some patients are not candidates for a transthoracic surgery and may need an alternative treatment strategy. In situations in which a posterior approach may be necessary, the authors have developed a minimal access endoscopic-assisted dorsal sympathectomy procedure, applying minimally invasive spine muscle splitting techniques. The authors believe that the development of this technique may help to minimize surgical morbidity associated with the traditional posterior approach by reducing pain, tissue damage, and length of postoperative recovery. This paper is a report on the successful treatment of palmar hyperhidrosis using a minimally invasive posterior technique and describes the surgical approach and outcomes in 2 patients who have been treated in this manner. Two patients underwent minimally invasive endoscopic-assisted posterior thoracic sympathectomy for hyperhidrosis. Both patients experienced relief of their symptoms after surgery with follow-up durations of 32 and 9 months and length of stays of 0.9 and 2.8 days, respectively. One patient suffered a unilateral Horner syndrome and underwent an eyelid lift. The other patient was readmitted to the hospital 2 days after discharge with atelectasis. She was obese and suffered from chronic obstructive pulmonary disease at baseline, which were reasons she opted for a posterior approach. Neither patient suffered a pneumo- or hemothorax. Minimally invasive endoscopic-assisted posterior thoracic sympathectomy can be safely performed for relief of hyperhidrosis. The procedure has risks for the usual complications of sympathectomy. This technique may provide an alternative to thoracoscopic approaches, especially in those patients with pulmonary disease or obesity.

Interaction between Dab1 and CrkII is promoted by Reelin signaling.

Reelin-induced Dab1 tyrosine phosphorylation has been implicated in the regulation of neuronal positioning during brain development. The downstream consequences of Dab1 tyrosine phosphorylation are not fully understood, however. Here we identify CrkII, CrkL and Dock1 in complexes bound to tyrosine-phosphorylated Dab1, through mass spectrometry. The CrkII-Dab1 interaction requires tyrosine phosphorylation of Dab1 at residues 220 or 232 and is promoted by Reelin treatment of embryonic forebrain neurons. Unlike other CrkII binding proteins, such as paxillin and p130Cas, expression of Dab1 interfered with CrkII-dependent cell migration of Nara Bladder Tumor II (NBT-II) cells, in a tyrosine phosphorylation-site dependent manner. Overexpression of CrkIIGFP rescued the migration of these cells, suggesting that Dab1 makes Crk a limiting factor for migration. The Dock1-Dab1 association is indirect and requires CrkII. In organisms such as Drosophila melanogaster and Caenorhabditis elegans, signaling complexes, which contain Crk and Dock1 family members are conserved and act through Rac. We show that a rough-eye phenotype in Drosophila caused by exogenous expression of tyrosine-phosphorylated mouse Dab1RFP is partially rescued by a loss-of-function mutation in myoblast city, a Dock1-like gene in Drosophila. We propose a model that tyrosine-phosphorylated Dab1 engages the conserved Crk-Dock1-Rac signaling cassette, but when bound to Dab1 this signaling complex does not support migration.