The neuroprotective effect of deep brain stimulation at nucleus basalis of Meynert in transgenic mice with Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common type of dementia and mainly treated by drugs, while the therapeutic outcomes are very limited. This study aimed to determine the optimized parameters of deep brain stimulation (DBS) which was applied to the treatment of AD and propose the involved mechanisms. METHODS: Amyloid-ß precursor protein/Presenilin1 (APP/PS1) transgenic mice were used and received DBS at nucleus basalis of Meynert (NBM). The optimized parameters of DBS were determined by using different stimulation frequencies, durations and ages of mice under Morris water maze test. The involved mechanisms and the possible signal pathways were also investigated. RESULTS: The optimized parameters for DBS were high frequency (100 Hz) for 21 days starting from early age (4 months old). Under the above parameters, the soluble Aß40 and Aß42 in the hippocampus and cortex were down-regulated significantly. DBS increased survival neurons and reduced apoptotic cells in the hippocampus and cortex. Meanwhile, the apoptosis-related proteins caspase-3, caspase-8 and Bid were down-regulated. Moreover, DBS caused a significant increase of superoxide dismutase, glutathione peroxidase and choline acetyltransferase activity as well as a decrease of methane dicarboxylic aldehyde content and acetylcholine esterase activity. Phosphorylation of Akt (p-Akt)/total Akt (t-Akt) was up-regulated while p-extracellular signal-regulated kinase 1/2 (ERK1/2)/t-ERK1/2 was down-regulated. The neuroprotective effect of DBS was attenuated by their inhibitors. CONCLUSIONS: NBM-DBS starting from 4 months of age for 21 days at a high frequency (100 Hz) has therapeutic effects on AD through activating phosphatidylinositol 3'-kinase (PI3K)/Akt pathway and inhibiting ERK1/2 pathway.

Evaluation of Mandarin Chinese Speech Recognition in Adults with Cochlear Implants Using the Spectral Ripple Discrimination Test.

BACKGROUND The aim of this study was to explore the value of the spectral ripple discrimination test in speech recognition evaluation among a deaf (post-lingual) Mandarin-speaking population in China following cochlear implantation. MATERIAL AND METHODS The study included 23 Mandarin-speaking adult subjects with normal hearing (normal-hearing group) and 17 deaf adults who were former Mandarin-speakers, with cochlear implants (cochlear implantation group). The normal-hearing subjects were divided into men (n=10) and women (n=13). The spectral ripple discrimination thresholds between the groups were compared. The correlation between spectral ripple discrimination thresholds and Mandarin speech recognition rates in the cochlear implantation group were studied. RESULTS Spectral ripple discrimination thresholds did not correlate with age (r=-0.19; p=0.22), and there was no significant difference in spectral ripple discrimination thresholds between the male and female groups (p=0.654). Spectral ripple discrimination thresholds of deaf adults with cochlear implants were significantly correlated with monosyllabic recognition rates (r=0.84; p=0.000). CONCLUSIONS In a Mandarin Chinese speaking population, spectral ripple discrimination thresholds of normal-hearing individuals were unaffected by both gender and age. Spectral ripple discrimination thresholds were correlated with Mandarin monosyllabic recognition rates of Mandarin-speaking in post-lingual deaf adults with cochlear implants. The spectral ripple discrimination test is a promising method for speech recognition evaluation in adults following cochlear implantation in China.

An optimized abnormal muscle response recording method for intraoperative monitoring of hemifacial spasm and its long-term prognostic value.

BACKGROUND: Intraoperative electrophysiological monitoring is used to determine whether decompression is sufficient during microvascular decompression (MVD) for hemifacial spasm (HFS). However, the real offending vessel is sometimes neglected by the neurosurgeons. Here, we reported our experience in using optimized abnormal muscle response (AMR) monitoring and continuous intraoperative monitoring for MVD. METHODS: This study included 2161 HFS patients who underwent MVD using traditional (1023 patients) and optimized (1138 patients) methods. Modified AMR monitoring was adopted in our study, with the zygomatic branch of the facial nerve stimulated and the temporal branch, buccal branch, marginal mandibular branch and cervical branch of the facial nerve detected for AMR. These cases were analyzed retrospectively with emphasis on the postoperative outcomes and intraoperative findings. The therapeutic effect was evaluated at day 1, month 3 and year 1 after operation. RESULTS: The relief rate at day 1, month 3 and year 1 after operation for patients who employed optimized AMR recording method was 95.1%, 97.4% and 99.3%, comparing with 92.2%, 95.0% and 97.8% in traditional method. There was significant difference in achieved immediate remission and recovery rate during 12-month follow-up between the two groups (P < 0.05). The modified intraoperative monitoring showed the sensitivity of AMR disappearance to judge the relief at day 1, month 3 and year 1 after HFS operation was 95.7%, 96.3% and 97.3%, respectively; the specificity was 44.6%, 43.3% and 50.0%, respectively; the accuracy was 93.1%, 94.9% and 97.4%, respectively. CONCLUSIONS: Our findings demonstrated that the optimized method could improve the positive detection rate of AMR and accuracy of decompression effect prediction. The evaluation for the decompression effect by optimized intraoperative monitoring can increase the immediate remission rate and reduce the delayed recovery rate.

Apelin-13 protects neurovascular unit against ischemic injuries through the effects of vascular endothelial growth factor.

Apelin-13 has protective effects on many neurological diseases, including cerebral ischemia. Here, we aimed to test Apelin-13's effects on ischemic neurovascular unit (NVU) injuries and investigate whether the effects were dependent on vascular endothelial growth factor (VEGF). We detected the expression of VEGF and its receptors (VEGFRs) induced by Apelin-13 injection at 1d, 3d, 7d and 14d after middle cerebral artery occlusion (MCAO). Meanwhile, we examined the effects of Apelin-13 on NVU in both in vivo and in vitro experiments as well as whether the effects were VEGF dependent by using VEGF antibody. We also assessed the related signal transduction pathways via multiple inhibitors. We demonstrated Apelin-13 highly increased VEGF and VEGFR-2 expression, not VEGFR-1. Importantly, Apelin-13 led to neurological functions improvement by associating with promotion of angiogenesis as well as reduction of neuronal death and astrocyte activation, which was markedly blocked by VEGF antibody. In cell cultures, Apelin-13 protected neurons, astrocytes and endothelial cells against oxygen-glucose deprivation (OGD) injuries. Moreover, the effect of Apelin-13 to up-regulate VEGF was suppressed by extracellular signal-regulated kinase (ERK) inhibitor U0126 and phosphatidylinositol 3'-kinase (PI3K) inhibitor LY294002. Our data suggest protective effects of Apelin-13 on ischemic NVU injuries are highly associated with the increase of VEGF binding to VEGFR-2, possibly acting through activation of ERK and PI3K/Akt pathways.

Subtotal facial nerve decompression for recurrent facial palsy in Melkersson Rosenthal syndrome.

CONCLUSIONS: Subtotal facial nerve decompression seems effective to prevent further episodes of facial palsy and promote facial nerve recovery for recurrent facial palsy in Melkersson Rosenthal syndrome (MRS). The main inflammatory sites of recurrent facial palsy in MRS may be the mastoid segment, tympanic segment, geniculate ganglion, and labyrinthine segment. OBJECTIVE: To present our surgical experience in preventing further episodes of facial palsy and improving facial nerve recovery of patients with recurrent facial palsy in MRS. METHODS: We performed transmastoid subtotal facial nerve decompression on eight patients with recurrent facial palsy in MRS. They were followed up for 3.3 years on average (range 2-5 years). RESULTS: There were no further attacks of facial palsy in any of the cases. Seven cases (87.5%) recovered to grade I or grade II, and three of eight cases (37.5%) recovered completely. We found obvious edema of the facial nerve at the mastoid segment in all cases, at the tympanic segment and geniculate ganglion in five cases (62.5%), and at the labyrinthine segment in only one case (12.5%).

Surgical experience of nine cases with intratemporal facial hemangiomas and a brief literature review.

CONCLUSIONS: It was practicable to remove hemangiomas at the labyrinth region and distal internal auditory canal with complete or serviceable hearing preservation by the transmastoid approach. The majority of cases where the nerve integrity was preserved achieved acceptable recovery of facial nerve function during the first few years according to our study. Long-term outcomes of nerve graft were acceptable, while short-term outcomes were unsatisfactory based on the literature. OBJECTIVE: This study aimed to present our surgical experience of nine intratemporal facial nerve hemangiomas and provide a brief literature review. METHODS: Clinical data for the cases were retrospectively analyzed. They were followed up for 5-59 months and related literature was reviewed. RESULTS: All of the hemangiomas were removed by the transmastoid approach, and only three cases developed mild conductive hearing loss. Nerve integrity was preserved for all cases. In all, 66.7% of patients maintained or recovered to grade III or better, and one patient with grade VI recovered to grade V during the average follow-up period of 2 years. In the literature the majority of grafted patients recovered to an acceptable level 5 years later, although recovery was usually poor during the first year.

Lateral hump anomaly of pyramid segment of facial nerve in living patients.

CONCLUSIONS: A lateral hump anomaly of the pyramid segment of the facial nerve deserves special attention during otologic surgery. Coronary high-resolution CT (HRCT) reconstruction of temporal bone was highly valuable in preoperative detection of the anomaly. OBJECTIVE: This study aimed to investigate lateral hump anomaly of the pyramid segment of the facial nerve in adult patients and assess the value of coronary HRCT reconstruction of the temporal bone in preoperative detection of the anomaly. METHODS: We carried out a prospective study in 439 Han Chinese adults who underwent unilateral facial nerve decompression due to Bell's palsy in our department between April 2005 and October 2012, focusing on lateral hump anomaly of the pyramid segment of the facial nerve, detection sensitivity, and accuracy of coronary HRCT reconstruction of the temporal bone. RESULTS: Lateral hump anomaly of the pyramid segment was observed in 21 cases (4.83%) undergoing surgery. The detection sensitivity and accuracy of coronary HRCT reconstruction were both 100%.

Surgical experience of intratemporal facial nerve neurofibromas.

CONCLUSIONS: The first presentation of intratemporal facial neurofibromas was variable, with facial palsy most common. The tumors often involve two or more segments of facial nerve. Outcomes of the tumors were closely related to nerve integrity, preoperative facial nerve function level, and follow-up period. OBJECTIVE: The aim of this study was to present surgical experience of 11 cases with intratemporal facial neurofibroma. METHODS: Clinical data of the 11 cases with the tumors was retrospectively collected and analyzed. They were followed up for 37.9 ± 1.7 months, range 13-59 months, except for one case that was only followed up for 5 months and was excluded from the analysis of outcomes. RESULTS: Facial palsy was the first presentation in 10 cases, with repetitive facial palsy and vertigo in 1 case; 6 cases (54.5%) were insidious and 5 (45.5%) were sudden in terms of onset. Ear pain around the onset of facial palsy was found in four cases (36.4%). The tumor involved more than one segment in six cases. Among the non-grafted cases one patient with grade V facial nerve function recovered to grade III and another patient with grade VI facial nerve function recovered to grade IV, whereas only one case with grade VI recovered to grade IV among the grafted cases.