Svetlana Pravdenkova

Chordoma and chondrosarcoma: Similar, but quite different, skull base tumors

Chordoma and chondrosarcoma of the skull base are frequently amalgamated because of similar anatomic location, clinical presentation, and radiologic findings. The chondroid chordoma variant has been reported to carry a better prognosis. The objective of the current study was to investigate the distinctions between these 3 entities.

DNA fragmentation and nuclear endonuclease activity in rat brain after severe closed head injury

Previous studies have suggested that brain cells undergo apoptotic cell death during several neurodegenerative disorders such as Alzheimers disease, Parkinsonism and ischemic stroke. In the present study, apoptotic DNA fragmentation and activation of nuclear endonuclease were evaluated in rat brain cells after head trauma. Severe closed head injury was induced in rats by the impact of a 450-g weight dropped from a height of 2 m. A 12% mortality was experienced after head trauma. Brain cell nuclei and DNA were isolated at intervals of 3, 10, 24 h, 3 and 10 days after head trauma. DNA fragmentation was measured by the random oligonucleotide-primed synthesis (ROPS) assay and was significantly increased with the maximum level of DNA fragmentation occurring at 10 h after trauma. The DNA and nuclei yields decreased 10 h after injury and remained at a reduced level at all subsequent sampling intervals. The DNA fragmentation induced after severe head trauma was accompanied by an increase in the activity of the Ca/Mg-dependent endonuclease associated with apoptosis. These data indicate that severe head injury is associated with significant brain cell death by apoptosis.

A role for telomeric and centromeric instability in the progression of chromosome aberrations in meningioma patients

The primary chromosome aberration in meningiomas is monosomy or deletion of chromosome 22. Common secondary aberrations include losses or deletions of chromosomes 1p, 14q, and 10q and unstable chromosome aberrations including rings, dicentrics, and telomeric associations. Despite the analysis of several hundred tumors by cytogenetic and molecular techniques, the mechanisms involved in the progression of chromosome aberrations in meningioma remain poorly understood.

Anterior clivectomy: surgical technique and clinical applications

OBJECT Midline clival lesions, whether involving the clivus or simply situated anterior to the brainstem, present a technical challenge for adequate exposure and safe resection. The authors describe, as a minimally invasive technique, an anterior clivectomy performed via an expanded transsphenoidal approach coupled with the use of a neuronavigation on mobile head and endoscopic-assisted technique. Wide and direct exposure, with the ability to resect extra- and intradural tumors, was achieved without mortality and with a low rate of complications. METHODS Cadaveric dissections were performed to outline the landmarks and measure the window that is created by resecting the clivus anteriorly. The technique was used in 43 patients to resect tumors located at or invading the clivus. The initial exposure of the clivus was obtained via the sublabial transsphenoidal approach. The wall of the anterior maxilla, often on 1 side, was removed to allow a wide side-to-side opening of the nasal speculum. Using neuronavigation, the authors made clivectomy windows by drilling the clivus between anatomical landmarks. Bilateral intraoperative neurophysiological monitoring was used (somatosensory evoked potentials, brainstem auditory evoked responses, and cranial nerves VI-XII). RESULTS Of the 43 patients, 26 were female and 17 were male, and they ranged in age from 3.5 to 76 years (mean 41.5 years). Thirty-eight patients harbored a chordoma and 5 a giant invasive pituitary adenoma. Gross-total resection of the tumor was achieved in 34 cases (79%). Nine patients (21%) had residual tumor unreachable through the anterior clivectomy, and this required a second-stage resection. Four patients developed new transient extraocular movement deficits. One patient developed a permanent cranial nerve VI palsy. Twenty-seven patients with chordoma underwent postoperative proton-beam radiotherapy. Tumor recurred in 19% of these cases. In 3 patients a cerebrospinal fluid leak developed during hospitalization and was treated successfully. Two other patients presented with a delayed cerebrospinal fluid leak after radiotherapy. Only 1 patient, who had previously undergone Gamma Knife surgery, experienced postoperative hemiparesis. CONCLUSIONS A complete anterior clivectomy via a simple extension of the transsphenoidal approach allows the surgeon access to different lesions involving the clivus or situated anterior to the brainstem. The exposure is similar to that provided by more extensive transfacial approaches. Instrument manipulation is easy. Neuronavigation, endoscopy, and intraoperative monitoring are easily incorporated and enhance the capability and safety of this approach.

Sequelae of Autologous Fat Graft Used for Reconstruction in Skull Base Surgery

BACKGROUND The use of an autologous free fat graft is a widely applied technique to obliterate dead space and reinforce dural closure during skull base reconstructions. The associated complications and outcomes of this practice have not been studied. Dissemination of fat in the subarachnoid space resulting in lipoid meningitis has been reported after translabyrinthine approaches, and leakage of liquefied fat is seldom reported in the literature. This study aims to evaluate the morbidity associated with the usage of autologous fat graft in reconstruction of skull base defects based on an extensive experience. METHODS This study is a retrospective review of 1581 cases in which the senior author (O.A.) used a skull base approach for the resection of tumor. Autologous fat grafts were used for reconstruction in 974 cases and 10 cases (male to female ratio, 4:6) in which there were associated complications were analyzed. RESULTS Complications included leakage of sterile liquefied fat from fistula (patients 1, 2, 3), delayed cerebrospinal fluid leak after radiation (Patients 5, 6, 9), and postoperative lipoid meningitis (Patients 4, 7, 8, 10). The onset ranged from 11 days to 10 years. Four patients were managed conservatively, and the other six required surgical intervention. All patients had good outcomes after treatment. CONCLUSIONS The use of autologous fat is associated with a 1% complication rate and should be considered a safe and effective method for skull base reconstruction. However, neurosurgeons should be aware of early and late complications of fat necrosis, including sterile liquefied fat fistula, cerebrospinal fluid leakage, and lipoid meningitis.

Meningiomas involving the optic canal: pattern of involvement and implications for surgical technique

OBJECT Juxtasellar meningiomas frequently extend into the optic canal. Removing these meningiomas from the optic canal is crucial for favorable visual outcome. METHODS The authors performed a retrospective analysis of 45 patients with anterior and middle fossa meningiomas with involvement of the optic pathway in whom surgery was performed by the senior author (O.A.M.) during the period from 1993 to 2007. Extent of resection and recurrence rates were determined by pre- and postoperative MR imaging studies. Visual outcomes were evaluated with full ophthalmological examinations performed before and after surgery. RESULTS Forty-five patients (31 women and 14 men) were involved in this study; their mean age was 51.6 years. Patients were followed for a mean of 29.8 months (range 6-108 months). No surgery-related death occurred. The average tumor size was 3.1 cm. Total resection of the tumor (Simpson Grade I) was achieved in 32 patients (71.1%). Gross-total resection (Simpson Grades II and III) was achieved in 13 patients (28.9%). Only 1 patient harboring a left cavernous sinus meningioma had tumor recurrence and underwent repeat resection. Meningiomas extended into 58 optic canals in these cases; 13 patients showed extension into both optic canals. Visual disturbance was the main presenting symptom in 37 patients (82.2%); 8 patients had normal vision initially. Visual improvement after surgery was seen in 21 (57%) of 37 patients and in 27 (34.6%) of 78 affected eyes. Vision remained unchanged in 48 (61.5%) of 78 eyes. Transient postoperative visual deterioration occurred in 2 eyes (2.6%), with recovery to baseline over time. Only 1 (1.3%) of 78 eyes had permanent visual deterioration after surgery. The visual outcome was affected mainly by the tumor size, the preoperative visual status, and the duration of symptoms. CONCLUSIONS Involvement of the optic canal in meningiomas is frequent. It occurs in a wide variety of anterior skull base meningiomas and it can be bilateral. It is a prominent factor that affects the preoperative visual status and postoperative recovery. Decompression of the optic canal and removal of the tumor inside is a crucial step in the surgical management of these tumors to optimize visual recovery and prevent tumor recurrence.

Impact of cytogenetic abnormalities on the management of skull base chordomas.

OBJECT Cytogenetic studies of chordomas are scarce and show multiple changes involving different chromosomes. These abnormalities are implicated in the pathogenesis of chordoma, but the clinical significance of these changes is yet to be determined. In this study, the authors discuss the cytogenetic changes in a large series of skull base chordomas with long-term follow-up and focus on the impact of these changes on the prognosis, progression, and management of the disease. METHODS The karyotypes of chordomas in 64 patients (36 men and 28 women) were studied in relation to survival and recurrence or progression over a mean follow-up period of 48 +/- 37.5 months. The standard G-banding technique was used for karyotype analysis. Statistical analysis was performed with the Fisher exact test and ORs, and Kaplan-Meier curves were generated for survival and recurrence/progression of disease. RESULTS Seventy-four percent of de novo chordomas had normal karyotypes and a 3% recurrence rate; there was a 45% recurrence rate in de novo tumors with abnormal karyotypes (p < 0.01). Recurrent tumors were associated with a high incidence of abnormal karyotype (75%). The OR for recurrence in lesions with an abnormal versus a normal karyotype was 12. Aberrations in chromosomes 3, 4, 12, 13, and 14 were associated with frequent recurrence and decreased survival time. Ninety-five percent of cases with progression involved chromosome 3 and/or 13. The median survival time was 4 months when both of these chromosomes had aberrations (p = 0.02). CONCLUSIONS Chordomas with normal karyotypes were associated with a low rate of recurrence and a long patient survival, and recurrent chordomas were associated with an abnormal karyotype, disease progression, and poor survival. De novo chordomas with normal karyotypes may be amenable to radical resection and adjunctive proton beam therapy. Recurrent and de novo chordomas with abnormal karyotypes were associated with complex cytogenetic abnormalities and a poor prognosis, particularly in the presence of aberrations underlying tumor progression in chromosomes 3, 4, 12, 13, and 14.

The posterior petrosal approach: technique and applications in pediatric neurosurgery

OBJECT Various lesions occur in deep locations or at the skull base in pediatric patients and require skull base approaches for resection. Skull base surgery confers the advantages of improved line of sight, a wider operative corridor, and reduced brain retraction. The posterior petrosal approach provides simultaneous access to lesions in the posterior middle fossa and posterior fossa from the top of the clivus to the level of the jugular foramen. It allows visualization of the ventrolateral brainstem and may be combined with various other supra- and infratentorial approaches, thus giving the surgeon a wide array of access routes to the lesion. METHODS The authors conducted a retrospective review of all cases involving pediatric patients undergoing a posterior petrosal approach, either alone or in combination with other cranial approaches. Preoperative and postoperative data were collected, including presentation, neurological examination, imaging findings, pathological condition, operative details, perioperative complications, and postoperative outcomes. RESULTS There were 13 patients (6 female, 7 male) with a mean age of 12.6 years (range 14 months-9 years). The posterior petrosal was the sole skull base cranial approach in 4 patients, whereas the posterior petrosal was combined with 1 or more other cranial approaches in 9. A gross-total resection was achieved in 7 patients, subtotal resection in 5, and a biopsy was performed in 1. Complications occurred in 9 patients, including 7 new or worsened cranial neuropathies. There was no perioperative mortality. CONCLUSIONS Although infrequently used in pediatric neurosurgery, the posterior petrosal approach is a highly versatile approach that can access intra- and extraaxial pathology centered on the petrous bone. The authors believe that patient outcomes are directly related to the degree of experience using this approach. Therefore, if this approach is to be used, they recommend collaboration with a skull base neurosurgeon.

A technical note on endonasal combined microscopic endoscopic with free head navigation technique of removal of pituitary adenomas.

Pituitary surgery exemplifies the continuous refinement of surgical techniques. The transsphenoidal approach is the approach of choice to treat most pituitary adenomas. We report here, as a technical note, an operative nuance that represents an encompassment of various technical steps that we utilize in our current surgery, including the corroboration of navigation system on a free head with combined use of endoscope and microscope techniques.

Giant intracranial epidermoids: is total removal feasible?

OBJECT Epidermoid tumors arise from misplaced squamous epithelium and enlarge through the accumulation of desquamated cell debris. Optimal treatment consists of total removal of the capsule; therefore, giant and multicompartmental tumors are particularly challenging. A conservative attitude in handling the tumor capsule is common given concerns about capsule adherence to neurovascular structures, and thus the possibility of recurrence is accepted with the intent of minimizing complications. This study focuses on the outcome of surgery in patients with giant epidermoid tumors for which total capsule removal was the aim. METHODS The authors conducted a retrospective analysis of all patients with giant epidermoid tumors treated by the senior author (O.A.), who pursued total removal of the capsule through skull base approaches. Patients were divided into 2 groups: one including patients with de novo tumors and the other consisting of patients who presented with recurrent tumors. RESULTS Thirty-four patients had undergone 46 operations, and the senior author performed 38 of these operations in the study period. The average tumor dimensions were 55 × 36 mm, and 25 tumors had multicompartmental extensions. Total removal of the tumor and capsule was achieved with the aid of the microscope in 73% of the 26 de novo cases but in only 17% of the 12 recurrent tumor cases. The average follow-up among all patients was 111 months (range 10-480 months), and the average postsurgical follow-up was 56.8 months (range 6-137 months). There were 4 recurrences in the de novo group, and every case had had a small piece of tumor capsule left behind. One patient died after delayed rupture of a pseudoaneurysm. In the de novo group, the average preoperative Karnofsky Performance Scale (KPS) score was 71.42%, which improved to 87.14% on long-term follow-up. In the group with recurrences, the KPS score also improved on long-term follow-up, from 64.54% to 84.54%. In the de novo group, 3 cases (11.5%) had permanent cranial nerve deficits, and 4 cases (15.4%) had a CSF leak. In the recurrence group, 3 cases (25%) had new, permanent cranial nerve deficits, and 1 (8.3%) had a CSF leak. Two patients in this group developed hydrocephalus and required a shunt. CONCLUSIONS Total removal of the capsule of giant epidermoid tumors was achieved in 73% of patients with de novo tumors and was associated with improved function, low morbidity and mortality, and a lower risk of recurrence. Surgery in patients with recurrent tumors was associated with higher morbidity and persistence of the disease.