Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles.

BACKGROUND: A lot of options have been tried for bridging the two ends of the injured nerves. Researchers have used decellularized nerve grafts, artificial materials and even nerve growth factors to augment functional recovery. These materials are either costly or inaccessible in developing world. OBJECTIVE: The study aimed to evaluate the efficacy of the silicone conduit in a rat sciatic nerve injury model. MATERIALS AND METHODS: 24 healthy Sprague-Dawley (SD) rats (250-300 grams; 8-10 weeks) were used and right sciatic nerve was exposed; transected and re-anastomosed by two different methods in 16 rats. In control group, n = 8 (Group I) the sciatic nerve was untouched; Group II (reverse nerve anastomosis, n = 8): 1-centimeter of nerve was cut and re-anastomosed by using 10-0 monofilament suture; Group III (silicone conduit, n = 8) 1-centimeter nerve segment was cut, replaced by silicone conduit and supplemented by fibrin glue]. Evaluation of nerve recovery was done functionally (pain threshold and sciatic functional index) over 3 months and histologically and electron microscopically. RESULTS: Functional results showed a trend of clinical improvement in Group III and II but recovery was poor and never reached up to normal. Histopathological and electron microscopic results showed an incomplete axonal regeneration in Groups II and III. Psychological analyses showed that no outwards signs of stress were present and none of the rats showed paw biting and teeth chattering. CONCLUSION: The silicone conduit graft may be an economical and effective alternative to presently available interposition grafts, however for short segments only.

Pathologic Laughter as an Early and Unusual Presenting Symptom of Petroclival Meningioma: a Case Report and Review of the Literature.

BACKGROUND: Pathologic laughter is inappropriate, involuntary, and unmotivated laughter episodes that may or may not be associated with mirth or amusement. Although associated with many diffuse brain pathologies, its association with intracranial focal mass lesions causing ventrolateral brainstem compression, like petroclival meningioma, is very rare. The exact pathophysiology of this interesting and unusual clinical symptom is unknown, but probably involves disinhibition and release of the so-called coordination center located in the upper brainstem due to compression by the tumor. CASE DESCRIPTION: A 26-year-old woman presented with recurrent episodes of inappropriate and involuntary laughter, which significantly affected her quality of life, for 2 years. These episodes did not resolve, and a magnetic resonance imaging of the brain showed a giant petroclival meningioma causing upper brainstem compression. Near-total excision of the tumor was done using an extended middle fossa approach. To our surprise, the pathologic laughter subsided immediately after surgery. CONCLUSIONS: Pathologic laughter may be the only symptom of a focal mass lesion causing ventrolateral upper brainstem compression, like petroclival meningioma, well before other neurological sign/symptoms appear. Tumors causing ventral brainstem compression must be ruled out before the patient is sent for a psychiatric evaluation.