No abstract

Little is known about the reasons for occurrence of facial nerve palsy after removal of cerebellopontine angle tumors. Since the intra-arachnoidal portion of the facial nerve is considered to be so vulnerable that even the slightest tension or pinch may result in ruptured axons, we tested whether a graded stretch or controlled crush would affect the postoperative motor performance of the facial (vibrissal) muscle in rats. Thirty Wistar rats, divided into five groups (one with intact controls and four with facial nerve lesions), were used. Under inhalation anesthesia, the occipital squama was opened, the cerebellum gently retracted to the left, and the intra-arachnoidal segment of the right facial nerve exposed. A mechanical displacement of the brainstem with 1 or 3 mm toward the midline or an electromagnet-controlled crush of the facial nerve with a tweezers at a closure velocity of 50 and 100 mm/s was applied. On the next day, whisking motor performance was determined by video-based motion analysis. Even the larger (with 3 mm) mechanical displacement of the brainstem had no harmful effect: The amplitude of the vibrissal whisks was in the normal range of 50°-60°. On the other hand, even the light nerve crush (50 mm/s) injured the facial nerve and resulted in paralyzed vibrissal muscles (amplitude of 10°-15°). We conclude that, contrary to the generally acknowledged assumptions, it is the nerve crush but not the displacement-induced stretching of the intra-arachnoidal facial trunk that promotes facial palsy after cerebellopontine angle surgery in rats.

No abstract

BackgroundAfter facial nerve injury and surgical repair in rats, recovery of vibrissal whisking is associated with a high proportion of mono‐innervated neuro‐muscular junctions (NMJs). Our earlier work with Sprague Dawley (SD)/Royal College of Surgeons (RCS) rats, which are blind and spontaneously restore NMJ‐monoinnervation and whisking, showed correlations between functional recovery and increase of fibroblast growth factor‐2 (FGF2) and brain‐derived neurotrophic factor (BDNF) in denervated vibrissal muscles.MethodsWe used normally sighted rats (Wistar), in which NMJ‐polyinnervation is highly correlated with poor whisking recovery, and injected the vibrissal muscle levator labii superioris (LLS) with combinations of BDNF, anti‐BDNF, and FGF2 at different postoperative periods after facial nerve injury.ResultsRats receiving anti‐BDNF+FGF2 showed low NMJ‐polyinnervation and best recovery of whisking amplitude.ConclusionsRestoration of target reinnervation after peripheral nerve injury requires a complex mixture of trophic factors with a specific time course of availability for each of them.

SDT in patients after decompressive craniectomy may represent an additional bedside tool to assess the dimensions of the ventricular system, anatomical structures, e.g., subdural hygromas, hematomas, midline shifts, gyri and sulci. The measurement of the dimensions of all four ventricles by using SDT delivers accurate values and may be considered as an alternative to CCT or a trigger for CCT prior to further treatment.