Intracranial mucosa-associated lymphoid tissue (MALT) lymphoma.

Primary central nervous system lymphomas are a rare lymphoid tumor. A small proportion of these lymphomas are low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) subgroup. A primary MALT-lymphoma of the dura is very rare, with only a few reports. These low-grade tumors respond favorably to a combination of surgery and post-operative regional external beam radiotherapy. Differentiating these lesions from primary lymphomas or other dural-based lesions is therefore critical to determine clinical management and future prognosis. We report a 29-year-old patient with visual loss and dural-based MALT lymphoma and discuss the pertinent findings as well as the clinical management of patients with this unusual lesion.

A novel minimally invasive technique for spinal cord untethering.

OBJECTIVE: Minimally invasive surgical techniques have been described for the treatment of spinal pathology. Tethered cord syndrome is an under-diagnosed condition of abnormally rigid fixation of the spinal cord that results in spinal cord tension leading to ischemia. It can be the cause of incontinence, scoliosis, and chronic back and leg pain. In situations of spinal cord tether owing to fatty filum or tight filum terminale, the symptoms can be relieved by sectioning of the filum. We present a novel, minimally invasive technique for surgical untethering of the spinal cord by filum sectioning. The pathophysiology of tethered spinal cord and the advantages of minimally invasive surgical management of this entity are discussed. METHODS: Three patients (ages 14, 35, and 46 yr) presented with long-standing leg and back pain and neuroradiological features of tethered cord syndrome and thickened, fatty filum terminale. Two patients presented with scoliosis and, upon further history, had subclinical incontinence; one of these patients had abnormal urodynamic studies. RESULTS: All three patients underwent a minimally invasive approach to the L4/L5 level using the X-tube (Medtronic, Inc., Memphis, TN). A laminotomy was performed and the dura exposed. The dura was then opened and intradural microdissection delivered the fatty filum into the durotomy. Electrical stimulation was performed while the lower extremities and the anal sphincter were monitored for electromyographic activity. After acquisition of positive controls, the filum was identified by the lack of sphincter and lower extremity electromyographic responses and was then cauterized and cut. Dura was repaired with the use of endoscopic instrumentation. All patients had significant improvement of their leg and back pain, and one patient had resolution of the abnormal urodynamics. CONCLUSION: Tethered spinal cords can be safely and effectively untethered using minimally invasive surgery. This technique provides the advantage of reduced soft tissue injury, less postoperative pain, minimal blood loss, a smaller incision, and a shorter hospitalization. The minimal amount of tissue injury generated by this technique may also provide the added advantage of reduced scar formation and risk of retethering.

Oncogenesis and mutagenesis of pituitary tumors.

Although pituitary tumors may be present in up to 10% of the population, the pathophysiology of these lesions is not well characterized. Pituitary tumors are composed of monoclonal cell populations with disrupted control of replication pathways. The oncogenes and tumor suppressor genes that are common in other malignancies (i.e. jun, fos, myc, and p53) are rarely involved in the development of these tumors. However, oncogenes, such as gsp, can be present in up to 40% of hormonally active adenomas. The process of pituitary oncogenesis further appears to involve oncogenes such as cyclin E, cyclin D1, and the pituitary tumor transforming gene (PTTG). Finally, the cAMP signaling cascade plays a significant role in generation of both benign and malignant pituitary tumors. In this review, the biology of pituitary adenomas is explored with a special emphasis on potential targets for the development of targeted therapeutics.

Role of craniotomy in the management of pituitary adenomas and sellar/parasellar tumors.

The transphenoidal procedure has become the preferred approach in the surgical management of sellar/parasellar tumors. Nevertheless, specific indications remain for the transcranial approach and the objective of this review is to evaluate the available data on outcomes following transcranial or transphenoidal approaches to sellar/parasellar tumors. We assess the indications used for each approach and parameters that favor one over the other. Factors such as tumor size, consistency and configuration are important variables in choosing the transcranial approach. Other important considerations include persistent visual loss after incomplete decompression via the transphenoidal route, ectatic midline carotid arteries, co-existent intracranial aneurysms and sphenoid sinusitis. We review the data on visual and endocrinological outcomes following the transcranial or transphenoidal approach and provide an argument that, while there appears to be a trend towards greater visual improvement after transcranial surgery for large-to-giant pituitary adenomas, this benefit is offset by a greater risk of postoperative pituitary dysfunction. There is no difference in the rate of recurrence between the two procedures in the published literature. Overall, craniotomies will continue to play a role in the management of patients with sellar/parasellar tumors, although patient selection and careful preoperative evaluation are key elements in choosing the most appropriate approach.

Low incidence of subdural grid-related complications in prolonged pediatric EEG monitoring.

Invasive EEG monitoring is one of the best tools available for localization of epileptogenic foci in the brain. However, published data in mixed series of adult and pediatric patients show high incidence of epidural bacterial contamination, cerebrospinal fluid leakage, and skin infection after subdural electrode implantation. We sought to determine whether the complication rate from prolonged subdural electrode implantation would be lower in a purely pediatric series. Thirty-three subdural electrode implantation procedures were performed in 29 pediatric patients (age range 4-19) for an average of 7.2 days (range 3-14 days). Electrode number varied from 32 to >128 with a range of 4-11 electrode wires piercing the skin >1 cm from the primary incision. Of the 33 implantations and resections (66 craniotomies), 5 were for reimplantation. There were no permanent complications related to grid implantation. Transient complications included 1 case of prolonged prothrombin time and 1 patient with unexplained fever, both of which resolved upon removal of the grids. There were two culture-positive infections, one epidural and one superficial, both in patients undergoing reimplantation. There was no percutaneous cerebrospinal fluid leakage noted and no operation was aborted due to bleeding caused by grid placement. Our data suggest that subdural grid implantation in children is remarkably safe even for prolonged implantation, though infectious risk is significantly higher in reoperation (p = 0.019). This observation may contribute to lowering the threshold for two-stage invasive monitoring approaches in children with epilepsy.