Spinal Subdural Abscess Mimicking an Extradural Tumor: A Case Report.

Spinal subdural abscesses (SSAs) are rare pathologies presenting as encapsulated pus located intradurally and extramedullary. Although there is no uniform opinion on the cause of this pathology, approximately 50% of cases are attributed to Staphylococcus aureus infection. Here, we present a rare case of a female patient who presented to N.N. Burdenko Neurosurgical Center for treatment of an extradural tumor in the lower lumbar spine. She complained of acute lower back pain, lower limb muscle spasms, progressive lower limb weakness, numbness in toes, and increased frequency of defecation (five to six times per day). Intraoperatively, we discovered that the epidural space was clear and a subdural abscess was located and removed. The patient was started on antibiotics and recovered 29 days later. This case report illustrates an atypical SSA mimicking an extramedullary tumor on MRI.

Learning Curve and Early Results of Interlaminar and Transforaminal Full-Endoscopic Resection of Lumbar Disc Herniations.

Background Full-endoscopic spinal surgery is an evolving technique. A laborious learning phase is inevitable due to the complexity of the orientation and instrumentation. The goal of the present study is to evaluate a single surgeon's learning curve and early outcomes in full-endoscopic resection of lumbar disc herniations. Methods This was a prospective non-controlled single-surgeon cohort study. In 54 patients with 57 herniations, 41 interlaminar and 16 transforaminal resections were performed. Surgery time, severity of adhesive process in the spinal canal, complication rates and clinical outcomes (VAS, ODI, custom questionnaire, recurrence and re-operation rate) were assessed. Results In the interlaminar group, operative time has decreased from 60 ± 20 min in the first 20 operations to 45 ± 14 min in the following 17 (p=0.023). In the transforaminal group, operative time has decreased from 60 ± 16 min in the first 7 operations to 41 ± 12 min in following 9 (p=0.023). Severe adhesive process in spinal canal was associated with duration of symptoms greater than 2 years, longer surgery and higher risk of surgical complications. Four recurrent disc herniations were re-operated using full-endoscopic technique. VAS, ODI and pain medications significantly decreased in both groups and in re-operated patients. Conclusion The plateau of the learning curve and good short-term clinical results of full-endoscopic interlaminar and transforaminal surgery may be achieved after twenty operations, given extensive previous experience in microsurgery. Risk of complications at the learning phase may be decreased by excluding the patients with symptoms lasting over two years.

Fluorescence Diagnosis in Neurooncology: Retrospective Analysis of 653 Cases.

Objective: This study is to analyze fluorescence sensitivity in the diagnosis of brain and spinal cord tumors. Material and methods: The authors conducted a multicenter retrospective analysis of data on 653 cases in 641 patients: 553 of them had brain tumors and 88 spinal cord tumors. Brain tumor resection was performed in 523 patients, of whom 484 were adults and 39 children. The analyzed series was presented by 320 gliomas, 101 meningiomas, and 72 metastases. A stereotactic biopsy was performed in 20 patients and endoscopic surgery in 10 patients. In all cases, 20 mg/kg of 5-Aminolaevulinic acid was administered orally 2-h before surgery. All surgical interventions were performed with a microscope BLUE 400 to visualize fluorescence, while endoscopic surgery-with an endoscope equipped with a fluorescent module. Fluorescence spectroscopy was conducted in 20 cases of stereotactic biopsies and in 88 cases of spinal cord tumors. Results: Among adult brain tumors operated by microsurgical techniques, meningiomas showed the highest 5-ALA fluorescence sensitivity 94% (n = 95/101), brain metastases 84.7% (n = 61/72), low-grade gliomas 46.4% (n = 26/56), and high-grade gliomas 90.2% (n = 238/264). In children the highest 5-ALA visible fluorescence was observed in anaplastic astrocytomas 100% (n = 4/4) and in anaplastic ependymomas 100% (n = 4/4); in low-grade gliomas it made up 31.8% (n = 7/22). As for the spinal cord tumors in adults, the highest sensitivity was demonstrated by glioblastomas 100% (n = 4/4) and by meningiomas 100% (n = 4/4); Fluorescence was not found in gemangioblastomas (n = 0/6) and neurinomas (n = 0/4). Fluorescence intensity reached 60% (n = 6/10) in endoscopic surgery and 90% (n = 18/20) in stereotactic biopsy. Conclusion: 5-ALA fluorescence diagnosis proved to be most sensitive in surgery of HGG and meningioma (90.2 and 94.1%, respectively). Sensitivity in surgery of intracranial metastases and spinal cord tumors was slightly lower (84.7 and 63.6%, correspondingly). The lowest fluorescence sensitivity was marked in pediatric tumors and LGG (50 and 46.4%, correspondingly). Fluorescence diagnosis can also be used in transnasal endoscopic surgery of skull base tumors and in stereotactic biopsy.

Surgical Treatment of Skull Base Tumors, Extending to Craniovertebral Junction.

OBJECTIVE: To conduct a comparative analysis of 2 groups of patients with skull base chordomas extending onto the craniovertebral junction, who underwent surgical treatment using extracranial approaches with and without craniocervical fusion. METHODS: The study group included 29 patients with skull base chordomas, extending to the craniovertebral junction, who were operated on from 2000 to 2015. The patients underwent the following surgical treatment: posterior craniocervical fusion followed by tumor removal using transoral and combined transoral and transnasal approaches. The reference group included 21 patients with the same disease, who underwent tumor removal surgery using the transoral approach without craniocervical fusion. RESULTS: In the study group, in 27.5% of all cases (8 patients), the tumors were removed radically; in 65.5% of all cases (19 patients), the tumors were removed subtotally; and in 7% of all cases (2 patients), the tumors were removed partially. In the reference group, the extent of surgical radicality was as follows: radical, 0%; subtotal, 19% (4 cases); partial, 81% (17 cases). CONCLUSIONS: Use of the proposed surgical technique in clinical practice may help increase the radicality of tumor excisions, decrease the number of postoperative complications, accelerate the rehabilitation process, and increase the quality of life in patients with skull base tumors extending to the craniovertebral junction.

Remission spectrometry for blood vessel detection during stereotactic biopsy of brain tumors.

Stereotactic biopsy is used to enable diagnostic confirmation of brain tumors and treatment planning. Despite being a well-established technique, it is related to significant morbidity and mortality rates mostly caused by hemorrhages due to blood vessel ruptures. This paper presents a method of vessel detection during stereotactic biopsy that can be easily implemented by integrating two side-view fibers into a conventional side-cutting biopsy needle. Tissue within the needle window is illuminated through the first fiber; the second fiber detects the remitted light. By taking the ratio of the intensities at two wavelengths with strongly differing hemoglobin absorption, blood vessels can be recognized immediately before biopsy sampling. Via ray tracing simulations and phantom experiments, the dependency of the remission ratio R = I578 /I650 on various parameters (blood oxygenation, fiber-to-vessel and inter-fiber distance, vessel diameter and orientation) was investigated for a bare-fiber probe. Up to 800-1200 µm away from the probe, a vessel can be recognized by a considerable reduction of the remission ratio from the background level. The technique was also successfully tested with a real biopsy needle probe on both optical phantoms and ex-vivo porcine brain tissue, thus showing potential to improve the safety of stereotactic biopsy. Dual-wavelength remission measurement for the detection of blood vessels during stereotactic biopsy.

405 nm versus 633 nm for protoporphyrin IX excitation in fluorescence-guided stereotactic biopsy of brain tumors.

Fluorescence diagnosis may be used to improve the safety and reliability of stereotactic brain tumor biopsies using biopsy needles with integrated fiber optics. Based on 5-aminolevulinic-acid-induced protoporphyrin IX (PpIX) fluorescence, vital tumor tissue can be localized in vivo during the excision procedure to reduce the number of necessary samples for a reliable diagnosis. In this study, the practical suitability of two different PpIX excitation wavelengths (405 nm, 633 nm) was investigated on optical phantoms. Violet excitation at 405 nm provides a 50-fold higher sensitivity for the bulk tumor; this factor increases up to 100 with decreasing fluorescent volume as shown by ray tracing simulations. Red excitation at 633 nm, however, is noticeably superior with regard to blood layers obscuring the fluorescence. Experimental results on the signal attenuation through blood layers of well-defined thicknesses could be confirmed by ray tracing simulations. Typical interstitial fiber probe measurements were mimicked on agarose-gel phantoms. Even in direct contact, blood layers of 20-40 µm between probe and tissue must be expected, obscuring 405-nm-excited PpIX fluorescence almost completely, but reducing the 633-nm-excited signal only by 25.5%. Thus, 633 nm seems to be the wavelength of choice for PpIX-assisted detection of high-grade gliomas in stereotactic biopsy. PpIX signal attenuation through clinically relevant blood layers for 405 nm (violet) and 633 nm (red) excitation.