Variability in the size of the retroperitoneal oblique corridor: A magnetic resonance imaging-based analysis.

BACKGROUND: A minimally invasive approach to the L2-S1 disc spaces through a single, left-sided, retroperitoneal oblique corridor has been previously described. However, the size of this corridor varies, limiting access to the disc space in certain patients. Here, the authors retrospectively reviewed lumbar spine magnetic resonance imaging (MRI) in 300 patients to better define the size and variability of the retroperitoneal oblique corridor. METHODS: Lumbar spine MRI from 300 patients was reviewed. The size of the retroperitoneal oblique corridor from L2-S1 was measured. It was defined as the (1) distance between the medial aspect of the aorta and the lateral aspect of the psoas muscle from L2-L5 and (2) the distance between the midpoint of the L5-S1 disc and the medial aspect of the nearest major vessel on the left at L5-S1. In addition, the rostral-caudal location of the iliac bifurcation was measured. RESULTS: The size of the retroperitoneal oblique corridor at L2/3, L3/4, L4/5, and L5/S1 was, respectively, 17.3 ± 6.4 mm, 16.2 ± 6.3 mm, 14.8 ± 7.8 cm, and 13.0 ± 8.3 mm. The incidence of corridor size <1 cm at L2/3, L3/4, L4/5, and L5/S1 was 10.3%, 16.0%, 30.0%, and 39.3%, respectively. The iliac bifurcation was most commonly found behind the L4 vertebral body (n = 158, 52.67%) followed by the L4/5 disc space (n = 74, 24.67%). CONCLUSION: The size of the retroperitoneal oblique corridor diminishes in a rostral-caudal direction, often limiting access to the L4/5 and L5/S1 disc spaces.

Variation in Psoas Muscle Location Relative to the Safe Working Zone for L4/5 Lateral Transpsoas Interbody Fusion: A Morphometric Analysis.

BACKGROUND: The safe working zone for lateral access to the L4/5 disc space has been said to lie in the anteroposterior (AP) midpoint of the disc space due to the location of the femoral nerve at that level. However, the AP location of the psoas muscle (and thus the lumbosacral plexus within) at L4/5 is variable. A psoas muscle lying excessively anteriorly at the L4/5 disc space may preclude safe access to the L4/5 disc space from a lateral transpsoas approach. METHODS: Lumbar spine magnetic resonance imaging (MRI) for 300 consecutive patients at the authors' institution were reviewed retrospectively. The AP distance between the ventral aspect of the thecal sac and the dorsal aspect of the psoas muscle at L4/5 was measured, as was the AP diameter of the L4/5 disc space. RESULTS: The dorsal aspect of the psoas muscle at L4/5 was most commonly found dorsal to the ventral aspect of the thecal sac (zone P, N = 145; 48.3%), whereas it was found at the junction of zones IV/P in 37 patients (12.3%), in zone IV in 85 patients (28.3%), in zone III in 29 patients (9.7%), and in zone II in 4 patients (1.3%). CONCLUSIONS: The location of the psoas muscle in relation to the L4/5 disc space is somewhat variable. In 11% of patients, the dorsal-most aspect of the psoas muscle was located within zones II or III, likely precluding safe access to the L4/5 disc space from a lateral transpsoas approach.

Spinal Schwannoma and Meningioma Mimicking a Single Mass at the Craniocervical Junction Subsequent to Remote Radiation Therapy for Acne Vulgaris.

BACKGROUND: Schwannomas and meningiomas are relatively common tumors of the nervous system. They have been reported in the literature as existing concurrently as a single mass, but very rarely have they been shown to present at the craniocervical junction. CASE DESCRIPTION: We present a rare and interesting case of a patient previously treated with radiation therapy for acne vulgaris and who presented to us with a concurrent schwannoma and meningioma of the craniocervical junction mimicking a single mass. CONCLUSIONS: These tumors can be solitary or mixed masses, and are known to be associated with certain disease processes such as long-term sequelae of radiation therapy and neurofibromatosis type 2. The precise mechanism behind the formation of these tumors is unknown; however, molecular cues in the tumor microenvironment may play a role.

Surgical approaches to meningiomas of the lateral ventricles.

BACKGROUND: Intraventricular meningiomas account for 0.5-3% of all intracranial meningiomas. The majority occur in the atrium of the lateral ventricle. Surgical experience with intraventricular meningiomas is rare in the literature, and several surgical approaches exist. METHODS: Between 1987 and 2007, 13 patients underwent resection of intraventricular meningiomas. All patients had tumors of the lateral ventricles. These patients were retrospectively identified and their records reviewed. RESULTS: Eleven tumors were found in the atrium, one in the frontal horn, and one in the body of the lateral ventricle. In 9 of 13 cases, the tumor occurred in the left lateral ventricle. Patients commonly presented with headache and cognitive difficulties. A visual field deficit was noted preoperatively in one patient. Four patients underwent preoperative angiography, but no patients underwent embolization. Gross total resection was achieved in all cases: 6 via a middle temporal gyrus approach, 5 via a superior parietal lobule approach, and 2 via a transcallosal approach. Image-guided stereotaxis was used in 6 cases. Pathology was benign in 12 of 13 cases; atypical features were identified in one case. There was no operative mortality, and no patients showed evidence of recurrence. Postoperatively, 3 patients developed new cognitive-linguistic deficits that subsequently resolved. One of these patients developed a new visual field deficit after surgery. CONCLUSIONS: Several approaches are available for the surgical treatment of intraventricular meningiomas. Tumor location, extension, and laterality drive the selection algorithm for these approaches. Preoperative angiography is rarely useful, and surgical cure is the rule.

Surface-supported multilayers decorated with bio-active material aimed at light-triggered drug delivery.

In this work, we report on the functionalization of layer-by-layer films with gold nanoparticles, microcapsules, and DNA molecules by spontaneous incorporation into the film. Exponentially growing films from biopolymers, namely, hyaluronic acid (HA) and poly-L-lysine (PLL), and linearly growing films from the synthetic polymers, namely, poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were examined for the embedding. The studied (PLL/HA)(24)/PLL and (PAH/PSS)(24)/PAH films are later named HA/PLL and PSS/PAH films, respectively. The HA/PLL film has been found to be more efficient for both particle and DNA embedding than PSS/PAH because of spontaneous PLL transport from the interior of the whole HA/PLL film to the surface in order to make additional contact with embedded particles or DNA. DNA and nanoparticles can be immobilized in HA/PLL films, reaching loading capacities of 1.5 and 100 microg/cm(2), respectively. The capacities of PSS/PAH films are 5 and 12 times lower than that for films made from biopolymers. Polyelectrolyte microcapsules adsorb irreversibly on the HA/PLL film surface as single particles whereas very poor interaction was observed for PSS/PAH. This intrinsic property of the HA/PLL film is due to the high mobility of PLL within the film whereas the structure of the PSS/PAH film is "frozen in". Gold nanoparticles and DNA form micrometer-sized aggregates or patches on the HA/PLL film surface. The diffusion of nanoparticles and DNA into the HA/PLL film is restricted at room temperature, but DNA diffusion is triggered by heating to 70 degrees C, leading to homogeneous filling of the film with DNA. The film has not only a high loading capacity but also can be activated by "biofriendly" near-infrared (IR) laser light, thanks to the gold nanoparticle aggregates on the film surface. Composite HA/PLL films with embedded gold nanoparticles and DNA can be activated by light, resulting in DNA release. We assume that the mechanism of the release is dependent on the disturbance in bonding between "doping" PLL and DNA, which is induced by local thermal decomposition of the HA/PLL network in the film when the film is exposed to IR light. Remote IR-light activation of dextran-filled microcapsules modified by gold nanoparticles and integrated into the HA/PLL film is also demonstrated, revealing an alternative release pathway using immobilized light-sensitive carriers (microcapsules).

Respiratory failure caused by Chiari I malformation with associated syringomyelia.

The authors report a case of a 38-year-old male with a Chiari I malformation and syringomyelia that presented with acute respiratory distress. Pulmonary function testing was consistent with respiratory muscle weakness. A suboccipital craniectomy and C1, 2, 3 laminectomies were performed on an emergent basis. Postoperatively the patient had significant improvement in his respiratory status associated with a reduction in the size of the syringomyelia on follow-up imaging.

Cutaneous metastasis of chordoma.

BACKGROUND: Chordomas are rare neoplasms that arise from the notochord remnant. They develop in the sacrococcygeal (50%) or cervical (15%) region and are generally regarded as a locally aggressive tumor with a slow progressive growth rate and a metastatic incidence ranging from 3 to 48%. Skin involvement by chordoma is rare, but can occur by direct extension, by local recurrence and by metastases. OBJECTIVE: To illustrate by a case report the clinical presentation and management of this disease. METHODS: We present a case of sacral chordoma with metastases over a 10-year period to the lungs, the soft tissue of the chest wall, the triceps tendon, and distant cutaneous metastases to the back and the nose. RESULTS: The cutaneous metastases were treated by excision. CONCLUSION: Chordoma is a slow growing tumor of the notochord remnant that may metastasize to the skin. Physicians and pathologists should be aware of this entity.

Visual loss associated with fibrous dysplasia of the anterior skull base. Case report and review of the literature.

The authors present a case of visual loss associated with fibrous dysplasia of the anterior skull base and the surgical management of this case. Preoperative computerized tomography scanning in this patient demonstrated a patent optic foramen and a rapidly growing cystic mass within the orbit, which was responsible for the patient's visual loss. A literature review revealed that this case is typical, in that cystic mass lesions of various types are frequently responsible for visual loss associated with fibrous dysplasia. The authors did not find significant evidence in the literature to support the notion that visual loss associated with fibrous dysplasia is the result of progressive optic canal stenosis, thus raising questions about the value of prophylactic optic canal decompression. Instead, as demonstrated by this case and those uncovered in the literature review, most instances of visual loss result from the rapid growth of mass lesions of cystic fibrous dysplasia, mucoceles, or hemorrhage. Findings of the literature review and the present case of fibrous dysplasia of the anterior skull base support a role for extensive surgical resection in these cases and indicate a need for additional prospective analysis of a larger number of patients with this disease.

Outpatient surgical treatment of cervical radiculopathy.

A series of 200 patients who underwent outpatient surgical treatment for cervical radiculopathy is presented. The patients were selected on the basis of their willingness to undergo surgery in the outpatient setting and the absence of serious underlying medical conditions. All operations were performed using general anesthetic techniques with limited posterior dissections. A laminoforaminotomy was performed at each affected level, which had been determined by preoperative imaging and clinical examination. After being observed for several hours, the patients were discharged if they met specific criteria. No patient required subsequent hospital admission in the immediate postoperative period. Follow-up review in 183 patients ranged from 3 to 43 months, with a mean of 19 months. In cases in which Workers' Compensation claims were not involved, 92.8% of patients reported an excellent or good outcome and returned to work or comparable duties at a mean of 2.9 weeks. In cases in which Workers' Compensation claims were involved, 77.8% of patients reported excellent or good outcome and returned to work at a mean of 7.6 weeks postoperatively. Two patients whose cases involved Workers' Compensation claims did not return to work. There were seven patients (3.8%) who had a poor outcome. Two of these patients underwent a second posterior procedure and reported a good outcome at the time of follow-up review. The results of this study show that outpatient surgical treatment of cervical radiculopathy can be safely provided in selected patients with outcomes similar to the inpatient surgical management of these individuals.

Anterior transcranial (craniofacial) resection of tumors of the paranasal sinuses: surgical technique and results.

Transfacial approaches, traditionally used for malignant tumors of the paranasal sinuses, provide limited exposure when several sinuses are involved and are unsuitable for tumors that erode through the floor of the anterior cranial fossa. A transcranial approach may aid in the removal of such lesions. To better understand the risks and benefits of this surgical approach, we reviewed all patients (n = 76) who underwent a transcranial approach as part of the excision of paranasal sinus lesions between 1984 and 1993 at our institution. The spectrum of disease included adenocarcinoma (13 patients), squamous cell carcinoma and olfactory neuroblastoma (11 patients each), adenoid cystic carcinoma and poorly differentiated forms of carcinoma (6 patients each), melanoma (5 patients), and miscellaneous others (24 patients). Most patients had ethmoid sinus involvement; tumors were also commonly found in the cribriform plate, sphenoid sinus, and nasal fossa. In each patient, a bifrontal craniotomy was performed with extradural dissection to the floor of the anterior fossa and osteotomies for resection of involved elements. In 47 patients (62%), disease in the orbit, the anterior nasal cavity, or the soft tissues of the face required transfacial as well as transcranial resections. Bony defect in the anterior fossa floor was repaired with a pedicled pericranial flap. Patients with major complications included six patients with epipericranial and/or epidural hematomas requiring evacuation, three with transient cerebrospinal fluid leaks, two who developed bifrontal cerebral infarcts, and one who died soon after surgery. No meningitis was seen. To date, 26 patients (34%) have died; of those living (mean follow-up, 34 mo), 42 (84%) remain in full remission. The transcranial approach can achieve removal of erosive, invasive tumors from this area with predictable morbidity and may be considered whenever sinus tumors breach the anterior cranial base or extend beyond the reach of conventional transfacial approaches.

Fracture of a sublaminar stainless steel cable in the upper cervical spine with neurological injury. Case report.

Sublaminar cables have been used to stabilize bone grafts for arthrodesis in the cervical spine in recent years. Previous accounts of their use have indicated no instances of breakage or neurological injury. This report is of a delayed cable fracture that resulted in penetration of the dura with neurological injury in a patient who had undergone atlantoaxial fusion for rheumatoid subluxation. The cable fracture occurred in the epidural space beneath the attempted arthrodesis and resulted in uncoiling of the cable, which penetrated spinal canal and caused a one-sided sensory deficit.

Cytokine responses to intraventricular injection of interleukin 2 into patients with leptomeningeal carcinomatosis: rapid induction of tumor necrosis factor alpha, interleukin 1 beta, interleukin 6, gamma-interferon, and soluble interleukin 2 receptor (Mr 55,000 protein).

Interleukin 2 (IL-2) is a potent immunostimulant that causes the release of secondary cytokines and the production of lymphokine-activated killer cells. We investigated the cellular and cytokine responses to injection of recombinant human IL-2 into the human cerebrospinal fluid of 11 patients with metastatic tumors involving the spinal or cerebral leptomeninges. After initial intraventricular IL-2 administration (1.25 x 10(5) to 2 x 10(6) Cetus units/injection), cerebrospinal fluid samples were collected at intervals from 0 to 24 h. Enzyme-linked immunosorbent assay results indicated that IL-2 levels gradually decreased during the first 24 h, with an average t1/2 between 4 and 8 h. Induction of tumor necrosis factor alpha, interleukin 1 beta, interleukin 6, gamma-interferon, and interleukin 2 receptor (p55) was also assessed by enzyme-linked immunosorbent assay. Tumor necrosis factor alpha and interleukin 6 levels peaked at 2 to 4 h and 4 to 6 h, with concentrations between 71 to 1,714 pg/ml and 942 to 10,500 pg/ml, respectively. Interleukin 1 beta, gamma-interferon, and soluble IL-2 receptor peaked later, during 6 to 12 h; the levels achieved were 234 pg/ml, 25 NIH units/ml, and 207 units/ml, respectively. All cytokine concentrations returned to near baseline between 12 and 24 h; however, the soluble IL-2 receptor levels remained elevated. Additional observations included a rapid influx of neutrophilic leukocytes, followed by a prolonged presence of lymphocytes. These data indicate a broad and complex potential of the immune response in the central nervous system, as well as further define the cytokine cascade in response to IL-2 alone.

Transcranial resection of tumors of the paranasal sinuses and nasal cavity.

Combined cranial and facial procedures for resection of malignancies of the paranasal sinuses and nasal cavity have been used with variable success and complication rates in the last 25 years. A series of nine patients undergoing 10 exclusively transcranial procedures for these tumors is presented, and an effective technique for reconstruction without free tissue transfer is described. The patients in this series suffered no major complications, and all have remained free of disease during the short follow-up period. The technique described in this report offers the advantage of wide exposure, symmetrical approach to the superstructures of the face and orbits, the potential for resection of a large portion of the anterior cranial floor, and substantial reconstruction which is a major factor in avoiding complications.

Superselective intra-arterial chemotherapy of advanced paranasal sinus tumors.

Twenty-four patients with advanced paranasal sinus tumors were treated with combined superselective intra-arterial and systemic chemotherapy, yielding an immediate satisfactory tumor response rate of 91%, significantly better than previously reported. Eight patients had craniofacial surgery circumvented because of complete or near complete response. Repetitive uncomplicated catheterization of the pterygoid segment of the internal maxillary artery using a coaxial system is the cornerstone of successful induction chemotherapy. Strenuous screening of medical status is mandatory for this aggressive introduction chemotherapy.

Vascular permeability induced by protein product of malignant brain tumors: inhibition by dexamethasone.

Serum-free conditioned medium derived from confluent monolayer cultures of malignant human astroglial tumors contains a substance that rapidly increases capillary vascular permeability after intradermal injection into guinea pigs. Accumulation of vascular permeability factor (VPF) activity occurs with increasing duration of tumor incubation in vitro. Expression of this activity is inhibited by incubation of cell cultures with cycloheximide or dexamethasone. This VPF is an acid-stable heat-labile macromolecule that is inactivated by trypsin and pepsin and binds immobilized heparin. Activity is retained by ultrafiltration with 30,000-dalton cut-off microconcentrators. Pretreatment of test animals with systemic dexamethasone prior to intradermal injection of VPF diminishes microvascular permeability. Furthermore, VPF activity is not inhibited by antihistamines. Secretion of VPF may cause the vasogenic brain edema that is frequently associated with malignant primary and metastatic intracerebral tumors. Inhibition by dexamethasone of both VPF expression in tissue culture, and VPF activity at the microvascular level in test animals, is in keeping with the known efficacy of this agent in treating the vasogenic edema associated with brain tumors.

Melanoma arising in a spinal nerve root. Case report.

Melanotic neoplasms of the spinal nerve root are rare but well-documented occurrences. The authors report the case of a 68-year-old woman with a malignant melanotic neoplasm containing premelanosomes and melanosomes and lacking a basal lamina. This tumor was found in a lumbar nerve root and is believed to represent an instance of a primary melanoma arising in a spinal nerve root. The differential diagnosis of pigmented lesions of spinal nerve root includes melanoma, pigmented nerve sheath tumor, blue nevus, melanotic clear-cell sarcoma, and meningeal melanocytoma. Surgeons should be aware of the potential for encountering unexpected malignant lesions involving spinal nerve roots.