Antonios Mammis

Malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are a rare variety of soft tissue sarcoma of ectomesenchymal origin. MPNSTs arise from major or minor peripheral nerve branches or sheaths of peripheral nerve fibers and are derived from Schwann cells or pluripotent cells of neural crest origin. Arthur Purdy Stout played a pivotal role in the development of our current understanding of the pathogenesis of peripheral nerve sheath tumors by identifying the Schwann cell as the major contributor to the formation of benign and malignant neoplasms of the nerve sheath. Although this fact remains essentially true, the cell of origin of the MPNST remains elusive and has not yet conclusively been identified. Some have suggested these tumors may have multiple cell line origins. In the present review, MPNSTs and their epidemiology, diagnosis, management, and treatment are discussed.

Erythropoietin for the Treatment of Subarachnoid Hemorrhage: A Review

OBJECTIVE Subarachnoid hemorrhage (SAH) has a worldwide incidence of approximately 10.5 cases per 100,000 person-years and constitutes 3% of all strokes. Erythropoietin (EPO) has recently been proposed for the treatment of a variety of brain diseases, including SAH, because of its neuroprotective effects. Hence, the current evidence in the published literature was reviewed to determine the potential utility of EPO in the treatment of SAH. METHODS A careful retrospective review of the literature was performed to determine the potential benefit of employing EPO in the treatment of SAH and its sequelae. RESULTS Careful literature review revelaed that the use of EPO may not necessarily reduce the incidence of vasospasm after SAH, but it may reduce the severity and its eventual outcome. CONCLUSION Given the recent trial results, a dose-escalation study and subsequent randomized trial should be considered.

Stackable carbon fiber cages for thoracolumbar interbody fusion after corpectomy: long-term outcome analysis.

BACKGROUND:Reconstruction of the thoracolumbar spine after corpectomy is a challenge for fractures, infections, and tumors. OBJECTIVE:To analyze fusion rates, clinical outcomes, and the percent of vertebral body coverage achieved by using stackable carbon fiber–reinforced polyetheretherketone cages in thoracolumbar corpectomies, and to measure the actual size of the cages and compare this measurement with the size of the vertebra(e) replaced by the cage. METHODS:A retrospective study of 40 patients who underwent thoracolumbar corpectomies was performed. Preoperative imaging included plain films, computed tomography scans, and magnetic resonance imaging. Postoperatively, plain films and computed tomography scans were obtained, and the width of decompression and cross-sectional area of the cage were measured. The ratio of the area of the cage to the calculated area of the replaced vertebral body was used to determine the percent of vertebral body coverage. RESULTS:The mean follow-up period was 43 months. Successful fusion was observed in 39 patients. One patient experienced cage subsidence with kyphosis. One additional patient incurred a neurological complication that was corrected without long-term consequence. The mean correction of sagittal alignment was 10°, and the mean width of bony decompression was 20 mm. The mean ratio of the area of the carbon fiber cage to the area of the resected vertebral body was 60%. CONCLUSION:Stackable carbon fiber cages are effective devices for achieving thoracolumbar fusions. No failures of the cages occurred over long-term follow-up. Excellent clinical and radiographic results were achieved by covering a mean of 60% of the vertebral body with the cage.

The use of intraoperative electrophysiology for the placement of spinal cord stimulator paddle leads under general anesthesia.

BACKGROUND: Placement of spinal cord stimulating paddle leads has traditionally been performed under local anesthesia with intravenous sedation to allow intraoperative confirmation of appropriate placement. It may be difficult to maintain appropriate sedation in certain patients because of medical comorbidities. Furthermore, patients undergoing lead revision frequently have extensive epidural scarring, requiring multilevel laminectomies to place the electrode appropriately. OBJECTIVE: To report our technique of neurophysiologic monitoring that allows these procedures to be performed under general anesthesia. METHODS: Data from 78 patients who underwent electromyography during laminectomy for paddle lead placement were retrospectively reviewed. Seventy patients presented for first-time permanent system placement after a successful trial, and 8 were referred for revision or replacement of previously functioning systems. Surgeries were performed under general anesthesia with fluoroscopic guidance. Electromyography was used to help define the physiological midline of the spinal cord and to guide appropriate lead placement. Somatosensory evoked potentials were used as an adjunct to minimize the possibility of neural injury. RESULTS: Immediately postoperatively, 75 of 78 patients reported that the paresthesia coverage was as good as (or better than) that of the spinal cord stimulation trial. At the long-term follow-up, 1 system was removed for infection, and 6 systems were explanted for lack of efficacy. A total of 64 of the 78 implanted patients reported continued pain relief with stimulator use. Revision surgery was performed in 9 patients. CONCLUSION: The use of intraoperative electrophysiology for the placement of spinal cord stimulation paddle leads under general anesthesia is a safe and efficacious alternative to awake surgery. ABBREVIATIONS: EMG, electromyography SCS, spinal cord stimulation

Intraventricular Tension Pneumocephalus after Endoscopic Skull Base Surgery

BACKGROUND AND STUDY AIMS Postoperative pneumocephalus is commonly observed after neurosurgical intracranial procedures and is usually of little consequence. Intraventricular tension pneumocephalus, however, is a rare complication and a neurosurgical emergency that requires immediate intervention. We describe the first case of intraventricular tension pneumocephalus that developed 1 week following an expanded endoscopic endonasal approach for resection of a suprasellar mass. PATIENT A patient who underwent an endoscopic transplanum transtuberculum approach for resection of a suprasellar epidermoid tumor developed a sudden change in mental status, with imaging consistent with intraventricular tension pneumocephalus. Immediate endotracheal intubation and placement of an external ventricular drain prevented further deterioration. Endoscopic exploration of the skull base reconstruction revealed a one-way ball valve mechanism as the source of pneumocephalus. The skull base reconstruction was revised with autologous fascia lata and repositioning of the pedicled nasoseptal flap. CONCLUSION Intraventricular tension pneumocephalus is a rare neurosurgical emergency that may develop after endoscopic skull base surgery. Initial management includes endotracheal intubation and placement of an external ventricular drain to decompress the ventricles. Endoscopic exploration and revision of the skull base repair is imperative to obliterate the ball-valve fistula to prevent further entrapment of air.

Revision of Chiari decompression for patients with recurrent syrinx

The management of adult patients with Chiari malformation associated with syrinx remains controversial. Although an abundance of literature exists for the pediatric population, there is an absence of guidelines for the adult population. It is unclear which of the different surgical approaches is appropriate in patients with Chiari I malformations and syringomyelia. A 36-year-old female patient had a posterior fossa decompression 3years prior to recurrence. The patient developed recurrent symptoms with sensory loss and hyperesthesia in the right upper extremity. MRI revealed decreased cerebrospinal fluid flow at the craniocervical junction. The patient was taken to the operating room for revision of the posterior fossa decompression, lysis of adhesions and duraplasty. Re-exploration of a Chiari decompression, lysis of adhesions and revision duraplasty is an effective treatment option for recurrent syringomyelia.

Presentation of cauda equina syndrome due to an intradural extramedullary abscess: a case report

BACKGROUND CONTEXT Cauda equina syndrome is caused by compression or injury to the nerve roots distal to the level of the spinal cord. This syndrome presents as low back pain, motor and sensory deficits in the lower extremities, and bladder as well as bowel dysfunction. Although various etiologies of cauda equina syndrome have been reported, a less common cause is infection. PURPOSE To report a case of cauda equina syndrome caused by infection of an intradural extramedullary abscess with Staphylococcus aureus. STUDY DESIGN/SETTING Case report and review of the literature. METHODS The literature regarding the infectious causes of cauda equina syndrome was reviewed and a case of cauda equina syndrome caused by infection of an intradural extramedullary abscess with Staphylococcus aureus was reported. RESULTS A 37-year-old woman, with history of intravenous drug abuse, hepatitis C, and hepatitis B, presented with low back pain lasting 2 months, lower extremity pain, left greater than right with increasing weakness and difficulty ambulating, and urinary and fecal incontinence. Her presentation was consistent with cauda equina syndrome. The patient underwent a T12-L2 laminectomy, and intradural exploration revealed an abscess. Methicillin-resistant Staphylococcus aureus was found on wound culture. CONCLUSIONS Cauda equina syndrome, presenting as a result of spinal infection, such as the case reported here, is extremely rare but clinically important. Surgical intervention is generally the recommended therapeutic modality.

The history of craniotomy for headache treatment

Both the history of headache and the practice of craniotomy can be traced to antiquity. From ancient times through the present day, numerous civilizations and scholars have performed craniotomy in attempts to treat headache. Today, surgical intervention for headache management is becoming increasingly more common due to improved technology and greater understanding of headache. By tracing the evolution of the understanding of headache alongside the practice of craniotomy, investigators can better evaluate the mechanisms of headache and the therapeutic treatments used today.

Alternative treatment of intracranial hypotension presenting as postdural puncture headaches using epidural fibrin glue patches: two case reports.

Introduction: Intracranial hypotension is a neurologic syndrome characterized by orthostatic headaches and, radiographically, by dural thickening and enhancement as well as subdural collections. Several of etiologies exist, including surgical dural violations, lumbar puncture, or spontaneous cerebrospinal fluid leak. Current management includes conservative management consisting of bed rest, caffeine, and hydration. When conservative management fails, open surgical or percutaneous options are considered. Currently, the gold standard in percutaneous management of intracranial hypotension involves the epidural injection of autologous blood. Recently, some therapies for intracranial hypotension have employed the use of epidural fibrin glue. Case Presentation: Two cases of patients with persistent postdural puncture headaches are presented. Epidural fibrin glue injection alleviated the orthostatic headaches of two patients with intracranial hypotension. Conclusion: Although consideration must be afforded for the potential risks of viral transmission and aseptic meningitis, the utilization of epidural fibrin glue injection as an alternative or adjunct to the epidural blood patch in the treatment of intracranial hypotension should be further investigated.

The use of deep brain stimulation in Tourette's syndrome.

Tourettes syndrome (TS) is a childhood neuropsychiatric disorder characterized by multiple involuntary motor and vocal tics. It is commonly associated with other behavioral disorders including attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, anxiety, depression, and self-injurious behaviors. Tourettes syndrome can be effectively managed with psychobehavioral and pharmacological treatments, and many patients experience an improvement in tics in adulthood. However, symptoms may persist and cause severe impairment in a small subset of patients despite available therapies. In recent years, deep brain stimulation (DBS) has been shown to be a promising treatment option for such patients. Since the advent of its use in 1999, multiple targets have been identified in DBS for TS, including the medial thalamus, globus pallidus internus, globus pallidus externus, anterior limb of the internal capsule/nucleus accumbens, and subthalamic nucleus. While the medial thalamus is the most commonly reported trajectory, the optimal surgical target for TS is still a topic of much debate. This paper provides a review of the available literature regarding the use of DBS for TS.