Prevalence, Laterality, and Classification of Ossified Petroclival Ligaments: An Anatomical and Histological Study With Application to Skull Base Surgery.

Background The petroclival ligament (PL) forms the roof of Dorello's canal (DC). In humans, partial and complete ossification of this ligament have been reported. When completely ossified, DC is transformed into a bony foramen for the abducens nerve and accompanying vascular structures. As this osteological finding might have an impact on skull base surgery, this anatomical study was performed. Methodology Using 100 adult human skulls, the presence of an ossified PL was noted and classified. The diameter of the resultant bony foramen and laterality were documented. Additionally, PL was evaluated histologically in 10 heads. Results Overall, 8% of the sides were found to have partial or complete ossification of the PL. Partial ossification (type I) was noted on 3% of the sides. Completely ossified PL was identified on 5% of the sides. Some ossified ligaments (2.5%) were seen as an ossified bridge (type II), and others (2.5%) were converted into small foramina (type III). Three skulls (3%) were found to have a completely ossified ligament bilaterally. The mean diameter of the underlying DC was 0.8 mm. Partially ossified ligaments were statistically more likely to be on the right sides, and the diameter of the underlying DC was statistically smaller in type III. Histologically, the PL was found to have bone within it on three skull sides. Conclusions An ossified ligament can be found on imaging of the skull base. Moreover, during surgical approaches to the petroclival region and, specifically, DC, skull base surgeons should be cognizant of this anatomical variation.

DCTN1-ALK gene fusion in inflammatory myofibroblastic tumor (IMT) of the CNS.

PURPOSE: Inflammatory myofibroblastic tumor (IMT) is a rare neoplastic tumor type of intermediate biological potential, only recently distinguished from the non-neoplastic category of inflammatory pseudotumor (IP). The literature describes very few cases of IMTs arising in the central nervous system (CNS), and the distinguishing clinical, pathological, and molecular features of IMT-CNS are not well understood. Our purpose is to publish a case of an IMT-CNS with a novel DCTN1-ALK gene fusion, furthering in the literature's characterization of a rare tumor type. METHODS: Review of the literature included a PubMed Database search of articles found by the following searches: "Inflammatory myofibroblastic tumor;" "Inflammatory myofibroblastic tumor central nervous system;" "ALK gene fusion;" and "DCTN1-ALK gene fusion." Inclusion of articles discovered by these search terms was determined through critical appraisal of article relevance, number of citations, cross-citation within articles of interest, and rare findings with conflicting conclusions in an effort to reduce publication bias. RESULTS: We present a case of IMT-CNS with several distinctive molecular features including a DCTN1-ALK gene fusion, the first of its kind described in an intracranial IMT. CONCLUSION: IMT is an infrequent tumor type and its presentation within the CNS is exceedingly rare. The paucity of cases, along with the ambiguity of terminology in the literature, has stunted accurate clinical, pathological, and molecular characterization of IMT-CNS. Our case report improves the characterization of the recently appreciated category of IMT-CNS so that connections between phenotype and prognosis, and between genotype and treatment, can eventually be made.

Primary Intraventricular Leiomyoma in an Immunocompetent Patient: First Case Report and Review of the Literature.

BACKGROUND: Primary intracranial leiomyoma is an extremely rare occurrence of a low-grade mesenchymal tumor characterized by a proliferation of smooth muscle cells. When present, these lesions predominantly occur in immunocompromised patients in the setting of infection or transplant and have not been known to involve the ventricular system of the brain. In this report, we describe a case of primary leiomyoma of the lateral ventricle in an immunocompetent patient. CASE DESCRIPTION: A 30-year-old man with no medical history presented with progressive diplopia and occipital headaches. Magnetic resonance imaging of the brain revealed a homogenously enhancing mass of the left lateral ventricle with associated cerebral edema. The patient underwent interhemispheric transcallosal craniotomy for resection for symptom alleviation and surgical diagnosis. Histopathology and immunohistochemistry was subsequently consistent with that of leiomyoma. Genetic probing for Epstein-Barr virus was negative. Computed tomography of the chest and abdomen failed to uncover a primary tumor. The patient did well postoperatively and was discharged 3 days after resection. At a two-and-a-half year follow-up, there continued to be no radiologic or clinical evidence of recurrence. CONCLUSIONS: To date and to our knowledge, there are fewer than 25 reported cases of primary intracranial leiomyoma, with only 13 occurring in immunocompetent individuals. We believe this is the first report of this tumor type occurring within the ventricular system of the brain. As such, leiomyoma should be considered as a rare etiology in the differential diagnosis of intraventricular lesions.

Intraoperative neurophysiological monitoring for minimally invasive 1- and 2-level transforaminal lumbar interbody fusion: does it improve patient outcome?

BACKGROUND: Despite the widespread use of intraoperative monitoring (IOM) in many types of spinal surgeries, an absence of data comparing monitored a nd unmonitored postoperative outcomes places IOM's efficacy into question. A lack of consensus among surgeons about when to use monitoring also raises concerns about its overuse in routine and low-risk procedures. METHODS: We performed a retrospective database review of 112 patients undergoing a 1- or 2-level minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF). Our analysis focused on patient demographics, use of IOM, length of surgery, hospital length of stay, the perioperative complication of pedicle screw malposition, and average hospital cost. RESULTS: For the 73 patients who underwent MIS-TLIF with intraoperative neuromonitoring, their hospital length of stay (P=0.8) and need for pedicle screw revisions (P=0.93) were not statistically significant compared to the 39 patients who underwent MIS-TLIF procedures without IOM. The incidence of reoperation was 5.48% and 5.13%, and average length of stay was 3.25 days and 3.13 days, respectively. However, the cost of surgery and the length of surgery were significantly higher in the monitored group compared to the nonmonitored group (P=0.008 and P=0.009, respectively). CONCLUSION: IOM is widely used in spine surgery, but our retrospective review shows that its use does not necessarily decrease the incidence of malpositioning of pedicle screws. In fact, no statistical difference was detected in the incidence of screw malposition in the 2 groups of patients. On the other hand, IOM adds cost and increases the length of surgery. Because the use of IOM did not make a difference in the incidence of pedicle screw malpositioning and because of the comparative cost analysis for both groups of patients, we believe that the use of IOM for MIS-TLIF provides no added benefit.