Brief Electrical Stimulation Promotes Nerve Regeneration Following Experimental In-Continuity Nerve Injury.

BACKGROUND: Brief electrical stimulation (ES) therapy to the nerve may improve outcome in lacerated, repaired nerves. However, most human nerve injuries leave the nerve in continuity with variable and often poor functional recovery from incomplete axon regeneration and reinnervation. OBJECTIVE: To evaluate the effect of brief ES in an experimental model for neuroma-in-continuity (NIC) injuries in rodents. METHODS: Lewis rats were randomly assigned to 1 of 4 groups: NIC injury immediately followed by brief (1 h) ES; NIC injury without ES; sham-operated controls; sciatic nerve transection without repair. Outcome measures included serial behavioral evaluation and electrophysiology together with terminal retrograde spinal cord motor neuron labeling and histomorphological analysis for axonal regeneration. RESULTS: Applying brief ES immediately after in-continuity nerve injury resulted in earlier recovery and significantly improved locomotion function at 4 and 6 wk. At 8 wk, brief ES resulted in higher compound action potential amplitude. By 12 wk there was no significant difference between the 2 groups in behavior or electrophysiology. Histomorphological analysis demonstrated a significantly higher percentage of neural tissue in the brief ES group. Spinal cord motor neuron pool cell counts revealed a preference for regeneration into a motor over a sensory nerve, for the group receiving ES. CONCLUSION: The application of brief ES for in-continuity nerve injury promotes faster recovery, although in a rat model where regeneration distances are short the control group ultimately recovers to a similar degree. Brief EF requires further evaluation as a promising therapy for in-continuity nerve injuries in humans.

Metastatic thymoma presenting as spontaneous epidural lumbar haematoma.

We report the case of a 44-year-old man who was found to have metastatic thymoma to his lumbar spine presenting as a spontaneous epidural haematoma. The man presented with back pain and cauda equina like symptoms in the absence of trauma, antiplatelet or anticoagulant agents. Following a laminectomy and excision of the epidural collection he made a full neurological recovery. Histopathology of the haematoma demonstrated metastatic thymoma. To the best of our knowledge, this is the first such case of metastatic thymoma to the lumbar spine presenting as a spontaneous epidural collection. We believe, in all patients with spontaneous spinal epidural haematoma and a background of malignancy, histopathological analysis should be sought.

Spinal intradural myxoid chondrosarcoma.

The authors present a rare case of intradural extramedullary spinal chondrosarcoma. This 38-year-old man presented with urinary retention and lower-limb weakness. Magnetic resonance imaging demonstrated a thoracic intradural extramedullary spinal tumor, which was resected. Histopathology revealed a meningeal myxoid chondrosarcoma. Despite adjuvant radiotherapy, the patient had multiple recurrences and metastases and died 18 months following his first surgery. The management of the rare entity of spinal canal chondrosarcoma is discussed.

Molecular responses of brain endothelial cells to radiation in a mouse model.

Although most small arteriovenous malformations (AVM) are curable, over 90% of large lesions are untreatable with current surgery or radiosurgery. Endothelial cells (EC) are believed to be pivotal in the resulting vascular changes after AVM are irradiated, although their role is not fully understood. Elucidating the molecular effects of radiation on EC may allow development of new therapies that modulate the response of AVM to radiation. Cultured murine cerebral EC (bEnd.3) were exposed to a single 25 Gy dose of ionising radiation from a linear accelerator. Expression of the membrane proinflammatory and thrombotic molecules E-selectin, tissue factor (TF) and thrombomodulin (TM) were examined by immunofluorescent staining at times up to three weeks post irradiation. We found that E-selectin is significantly down regulated in the first 24 hours after irradiation. Later there is no significant difference in expression of this molecule between irradiated and non-irradiated groups. TM expression was significantly increased at all times, and the staining intensity of TF remained unchanged three weeks post irradiation. These results contribute to a greater understanding of the proinflammatory and thrombotic changes caused by irradiating normal brain EC.

Endothelial cells in the context of brain arteriovenous malformations.

A subset of brain arteriovenous malformations (AVM) cannot be treated using today's treatment paradigms. Novel therapies may be developed, however, as the underlying pathophysiology of these lesions becomes better understood. Endothelial cells (EC) are the subject of new biological therapies, such as radiosensitisation and vascular targeting. This work reviews the current research surrounding EC in the context of brain AVM, including both in vitro and AVM specimen analysis, with a particular focus on the effect of radiation on EC. EC are heterogeneous with no recognised common phenotype, which leads to difficulties in applying the results of the common studies using human umbilical vein endothelial cells to AVM research. Human brain EC are observed to have a high rate of proliferation and also have a reduced apoptotic response to inflammatory mediators such as transforming growth factor-beta. The angiogenic factors vascular endothelial growth factor and endothelin-1 (ET-1) are not normally produced by quiescent brain vasculature, but are produced by AVM EC. Radiation causes EC to separate and become disrupted. Leucocyte and platelet adherence is increased for several days post-irradiation due to increased E-selectin and P-selectin and intercellular adhesion molecule-1 expression. ET-1 is highly expressed in irradiated AVM EC. Radiosurgery produces local radiation-induced changes in EC, which may allow these changes to be harnessed in conjunction with other techniques such as vascular targeting.

Treatment of a pontine neuroepithelial cyst by placement of a cystocisternal grommet.

We describe an 8-year-old girl who presented with cranial nerve compression due to a brainstem cyst adjacent to the fourth ventricle and describe the first documented insertion of a grommet to form a conduit between a neuroepithelial cyst and ventricle. The patient presented with diplopia and headaches and was found to have the cystic lesion in the right pons. The patient underwent craniotomy, aspiration and fenestration with subsequent recurrence 8 months later. Definitive treatment involved insertion of a grommet. Surgical treatment of symptomatic neuroepithelial cysts can achieve full resolution of neurological deficits. Insertion of a grommet, as distinct from a shunt or fenestration procedure, has the potential to provide long-term resolution of these symptoms without recurrence.

Resolution of hydrocephalus-associated sensorineural hearing loss after insertion of ventriculoperitoneal shunt.

The authors present a pediatric patient with severe hearing loss due to communicating hydrocephalus. This is the first clearly documented case of de novo sensorineural deafness caused by hydrocephalus, with subsequent improvement in hearing after shunt insertion. The patient initially presented with otitis media and was found to have hearing loss. After reporting ongoing headaches, he received a diagnosis of communicating hydrocephalus, which was treated with the insertion of a ventriculoperitoneal shunt. Formal hearing tests showed dramatic improvement postsurgery; his hearing was normal at 2 months. At 3 years postsurgery the patient's hearing remains within normal limits. Hearing loss is a rare complication of hydrocephalus. Based on this case, the authors suggest that the diagnosis of hydrocephalus be considered as a cause of unexplained hearing loss, and conversely, that patients with hydrocephalus might benefit from hearing assessment.