Intraneural Hematoma: A Proposed Anatomic Classification with Potential Treatment Implications.

Intraneural hematoma is a rare entity with fewer than 20 cases reported in the literature. There is no consensus on surgical treatment due to its rarity. We present a novel classification for intraneural hematomas based on a review of the literature and illustrated by 4 cases that were treated in our 3 centers. This classification system localizes the hematoma to the different connective tissue layers that compose the nerve: the paraneurium, epineurium, and perineurium. We believe that this classification has consequences for surgical treatment and can form the foundation for future research into the natural history of these types of lesions.

Safety and efficacy of vagus nerve stimulation in fibromyalgia: a phase I/II proof of concept trial.

OBJECTIVE: We performed an open-label Phase I/II trial to evaluate the safety and tolerability of vagus nerve stimulation (VNS) in patients with treatment-resistant fibromyalgia (FM) as well as to determine preliminary measures of efficacy in these patients. METHODS: Of 14 patients implanted with the VNS stimulator, 12 patients completed the initial 3-month study of VNS; 11 patients returned for follow-up visits 5, 8, and 11 months after start of stimulation. Therapeutic efficacy was assessed with a composite measure requiring improvement in pain, overall wellness, and physical function. Loss of both pain and tenderness criteria for the diagnosis of FM was added as a secondary outcome measure because of results found at the end of 3 months of stimulation. RESULTS: Side effects were similar to those reported in patients treated with VNS for epilepsy or depression and, in addition, dry mouth and fatigue were reported. Two patients did not tolerate stimulation. At 3 months, five patients had attained efficacy criteria; of these, two patients no longer met widespread pain or tenderness criteria for the diagnosis of FM. The therapeutic effect seemed to increase over time in that additional participants attained both criteria at 11 months. CONCLUSIONS: Side effects and tolerability were similar to those found in disorders currently treated with VNS. Preliminary outcome measures suggested that VNS may be a useful adjunct treatment for FM patients resistant to conventional therapeutic management, but further research is required to better understand its actual role in the treatment of FM.

Clock face model applied to tibial intraneural ganglia in the popliteal fossa.

BACKGROUND: Tibial intraneural ganglia occurring in the popliteal fossa are often misdiagnosed because of their relative rarity. Their joint connection is typically not recognized and therefore not treated, leading to recurrence. STUDY DESIGN: This is a retrospective clinical study. MATERIALS AND METHODS: Magnetic resonance images (MRIs) of six patients with confirmed tibial intraneural ganglia arising from the superior tibiofibular joint were analyzed and were compared to ten individuals with normal tibial nerves who were imaged with MRI. All studies were interpreted as left-sided. A previously designed clock face model introduced for peroneal intraneural ganglia was used to describe the superior tibiofibular joint connection (tail sign). A single axial image was sought to determine the normal anatomic and pathologic relationships of the tibial nerve and tibial articular branch to the superior tibiofibular joint. RESULTS: In all patients with intraneural ganglia, a single conventional axial image at the mid-fibular head level could reliably demonstrate: (1) intraneural cyst within the articular branch at the superior tibiofibular joint connection (tail sign) between 8 and 9 o'clock and intraneural cyst within the tibial nerve, (2) the central location of the tibial nerve posterior to the tibia, and (3) popliteus muscle denervation changes and atrophy (popliteus sign). CONCLUSIONS: This technique can provide radiologists and surgeons with rapid and reproducible information for diagnosis and treatment planning of tibial intraneural ganglia. Similar to its use with the clock face model in peroneal intraneural ganglia, a standard axial image at the mid-fibular head level can be used to interpret key features of tibial intraneural ganglia and identify the joint connection. Improved identification of the presence of a joint connection will change the therapeutic approach of this pathology and reduce cyst recurrences.

Erythropoietin as a neuroprotective agent in traumatic brain injury Review.

BACKGROUND: In the United States, TBI remains a major cause of morbidity and mortality in children and young adults. A total of 1.5 million Americans experience head trauma every year, and the yearly economic cost of this exceeds $56 billion. The magnitude of this problem has generated a great deal of interest in elucidating the complex molecular mechanism underlying cell death and dysfunction after TBI and in the development of neuroprotective agents that will reduce morbidity and mortality. METHODS: A review of recent literature on EPO, TBI, and apoptosis is conducted with analysis of pathophysiologic mechanisms of TBI. In addition, animal experiments and clinical trials pertaining to mechanisms of cell death in TBI and EPO as a neuroprotective agent are reviewed. CONCLUSION: The literature and evidence for EPO as a potent inhibitor of apoptosis and promising therapeutic agent in a variety of neurological insults, including trauma, are mounting. With the recent interest in clinical trials of EPO in human stroke, it is both timely and prudent to consider the use of this pharmaceutical avenue in TBI in man.

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.

The use of Hypertonic Saline in the Treatment of Post-Traumatic Cerebral Edema: A Review.

Effective methods for treating cerebral edema have recently become a matter of both extensive research and significant debate within the neurosurgery and trauma surgery communities. The pathophysiologic progression and outcome of different forms of cerebral edema associated with traumatic brain injury have yet to be fully elucidated. There are heterogeneous factors influencing the onset and progress of post-traumatic cerebral edema, including the magnitude and type of head injury, age, co-morbid conditions of the patient, the critical window for therapeutic intervention and the presence of secondary insults including hypoxia, hypotension, hypo/hyperthermia, degree of raised intracranial pressure (ICP), and disruption of blood brain barrier (BBB) integrity. Although numerous studies have been designed to improve our understanding of the etiology of post-traumatic cerebral edema, therapeutic interventions have traditionally been focused on minimizing secondary insults especially raised ICP and improving cerebral perfusion pressure. More recently, fluid resuscitation strategies using hyperosmolar agents such as pentastarch and hypertonic saline (HS) have achieved some success. HS treatment is of particular interest due to its apparent advantageous action over other types of hyper-osmotic solutions in both clinical and laboratory studies. In this review, we provide a summary of recent literature concerning the pathogenesis and mechanisms involved in the various types of cerebral edema, and the possible mechanisms of action of HS for the treatment cerebral edema.

Malignant peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas of ectomesenchymal origin. The World Health Organization coined the term MPNST to replace previous heterogeneous and often confusing terminology, such as "malignant schwannoma," "malignant neurilemmoma," "neurogenic sarcoma," and "neurofibrosarcoma." Malignant peripheral nerve sheath tumors 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. The Schwann cell is thought to be the major contributor to the formation of benign as well as malignant neoplasms of the nerve sheath. While this fact remains essentially true, the identity of cell of origin of the MPNST remains elusive, and has not yet been conclusively identified. It has been suggested that these tumors may have multiple cell line origins. In this review, the authors discuss the epidemiology, diagnosis, management, and treatment of MPNSTs.

Hemorrhagic complications of external ventricular drainage.

OBJECTIVE: Despite the widespread use of external ventricular drainage (EVD), the frequency of associated hemorrhagic complications remains unclear. This retrospective study examined the frequency of hemorrhagic complications of EVD and attempted to discern associated risk factors. METHODS: Treatment records from 160 patients admitted during a 2.5-year period who required EVD placement were reviewed. Indications for placement of EVD included acute complications of cerebrovascular disease (n = 94), traumatic brain injury (n = 36), primary hydrocephalus (n = 16), and tumor (n = 14). Patients received either a 3.0 or 2.5-mm outer diameter ventricular catheter (n = 82 and 78, respectively). Postinsertion computed tomographic scans were obtained within 24 hours on all patients and were analyzed for any new hemorrhage related to the ventricular catheter. Patient age, sex, catheter type, and dimensions of hemorrhage were also analyzed. RESULTS: The incidence of EVD-related hemorrhage was 33 +/- 0.04%. However, the incidence of detectable change in the clinical neurological examination was 2.5%. A significant proportion of EVD-related hemorrhages were small (<4 cm), punctate, intraparenchymal hematomas. Patients with cerebrovascular disease exhibited an increased incidence (39%) of hemorrhage. The mean volume of intraparenchymal hemorrhage was larger in patients who received the 2.5-mm ventricular catheter, as well as those admitted for cerebrovascular disease. CONCLUSION: Hemorrhagic complications of EVD placement are more common than previously suspected. Admitting diagnosis seems to have an effect on the development of an associated hemorrhage and its size. Catheter gauge has an effect on hematoma volume. Most of the hemorrhages seen on postinsertion computed tomographic scans do not cause detectable changes in the clinical examination.

Cranial surgery with an expanded compact intraoperative magnetic resonance imager. Technical note.

In this article the authors report the implementation of an expanded compact intraoperative magnetic resonance (iMR) imager that is designed to overcome significant limitations of an earlier unit. The PoleStar N20 iMR imager has a stronger magnetic field than its predecessor (0.15 tesla compared with 0.12 tesla), a wider gap between magnet poles, and an ergonomically improved gantry design. The additional time needed in the operating room (OR) for use of iMR imaging and the number of sessions per patient were recorded. Stereotactic accuracy of the integrated navigational tool was assessed using a water-covered phantom. Of the 55 patients who have undergone surgery in the PoleStar N20 device, diagnoses included glioma in 13, meningioma in 12, pituitary adenoma in nine, other skull base lesions in seven, and miscellaneous other diagnoses. The extra time required for use of the system averaged 1.1 hours (range 0.5-2 hours). Imaging sessions averaged 2.3 per surgery (range one-six sessions). Measurement of stereotactic accuracy revealed that T1-weighted images were the most accurate. Thinner slices yielded measurably greater accuracy, although this was of questionable clinical significance (all sequences < or =4 mm had a mean error of < or = 1.8 mm). The position of the phantom in the center compared with the periphery of the magnetic field did not affect accuracy (mean error 0.9 mm for each). The PoleStar N20 appears to make intraoperative neuroimaging with a low-field-strength magnet much more practical than it was with the first-generation device. Greater ease of positioning resulted in a decrease in added time in the OR and encouraged a larger number of imaging sessions.

Diagnostic steps, imaging, and electrophysiology.

The patient with a peripheral nerve tumor can present with a variety of signs and symptoms, including pain, motor weakness, sensory deficit, a palpable mass, and even as an asymptomatic incidental finding. Although most tumors that arise from nerve are solitary tumors associated with a single nerve, they may also be associated with global diseases, such as neurofibromatosis type I (von Recklinghausen's), in which case, there maybe multiple masses involving several nerves. Most peripheral nerve tumors are histologically benign; however, they may experience malignant degeneration, especially in the setting of neurofibromatosis. Treatment in the form of gross total surgical removal is therefore indicated in most nerve tumors for histologic diagnosis as well as for relief of symptoms. The goals of the initial diagnostic steps, imaging and electrophysiology, are to determine baseline clinical neurologic function, define anatomic location and extent of the tumor, and record baseline electromyographic parameters. Once these elements are defined, the surgeon may proceed to the operating room with a level of confidence as to how to approach the lesion and remove it safely. Biopsy of peripheral nerve tumors is to be discouraged over gross total removal, and this can be avoided by proper preoperative diagnostic workup.

Myokymia in obstetrically related brachial plexopathy.

Myokymic discharges are spontaneous bursts of semirhythmic potentials that are sometimes correlated with rippling movements of skin and muscle. They have been reported in limb muscles in patients with Guillain-Barré syndrome, spinal stenosis, nerve root and nerve compression, and envenomations. They commonly occur with radiation induced plexopathies (approximately 60% of patients), but have not been reported in obstetrically related brachial plexopathies. We report 2 instances of myokymia in children with obstetric brachial plexus palsies. Each child was studied twice, and it was only at the later study, when the child was 10 or 11 months of age, that these potentials were noted. This could represent ongoing recovery from lesions incurred at birth or developmental changes. The final common pathway of all causes of myokymia could be to generate axonal membrane hyperexcitability.

Traumatic venous varix causing sciatic neuropathy: case report.

OBJECTIVE AND IMPORTANCE: Sciatic neuropathy rarely presents in nonpenetrating trauma because of protection of the nerve by the pelvis, the gluteal muscles, and the tissues in the posterior thigh. We present the case of a patient who fell and subsequently developed a traumatic venous varix of the inferior gluteal vein that caused compression sciatic neuropathy. CLINICAL PRESENTATION: Seven days after a fall onto her right buttock, the patient developed a painful burning paresthesia in her leg and numbness on the dorsum of her foot. Numerous studies ruled out lumbar spine pathological abnormalities as the cause of the pain. Conventional magnetic resonance imaging revealed a lesion adjacent to the sciatic nerve. Gradient echo and two-dimensional time-of-flight magnetic resonance imaging sequences confirmed this to be a vascular lesion originating from the inferior gluteal vein and compressing the sciatic nerve. INTERVENTION: Operative resection obliterated the venous varix, thereby relieving the patient's pain and neurological deficit. CONCLUSION: No case of a traumatic venous varix of the inferior gluteal vein compressing the sciatic nerve has been reported to date. Surgical resection was successful in obliterating the lesion and relieving the symptoms.

Peripheral nerve surgery and neurosurgeons: results of a national survey of practice patterns and attitudes.

OBJECT: The goal of this study was to determine current practice patterns and attitudes of neurosurgeons toward peripheral nerve surgery. METHODS: A 13-question survey was mailed to all active members of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons. Collected responses were entered into a database and were analyzed using statistical software. CONCLUSIONS: Of 3800 surveys mailed there were 1728 responses for a 45% response rate. Analysis of the data revealed that respondents had a greater comfort level with simple peripheral nerve procedures, such as carpal tunnel release, and a lack of comfort with more complex peripheral nerve procedures, such as brachial plexus exploration. The majority of simple cases were treated by the surveyed neurosurgeons, whereas the majority of complex cases were referred to other surgeons, primarily to other neurosurgeons. The type of medical practice (academic, group, or solo) and the location of the practice (major city, small city, suburban setting, or rural area) showed a statistically significant correlation to simple case referral patterns, whereas the length of time since the respondent underwent training did not. Practice type and location, and years since training showed a statistically significant correlation to complex case referral patterns. Only 48.7% of the respondents believed that they had been given sufficient exposure to peripheral nerve surgery during residency training. The overwhelming majority (97.2%) of respondents favored keeping peripheral nerve surgery as part of the neurosurgical curriculum.