Central auditory maturation and behavioral outcome in children with auditory neuropathy spectrum disorder who use cochlear implants

Abstract

Objective: We examined cortical auditory development and behavioral outcomes in children with ANSD fitted with cochlear implants (CI). Design: Cortical maturation, measured by P1 cortical auditory evoked potential (CAEP) latency, was regressed against scores on the infant toddler meaningful auditory integration scale (IT-MAIS). Implantation age was also considered in relation to CAEP findings. Study sample: Cross-sectional and longitudinal samples of 24 and 11 children, respectively, with ANSD fitted with CIs. Results: P1 CAEP responses were present in all children after implantation, though previous findings suggest that only 50–75% of ANSD children with hearing aids show CAEP responses. P1 CAEP latency was significantly correlated with participants’ IT-MAIS scores. Furthermore, more children implanted before age two years showed normal P1 latencies, while those implanted later mainly showed delayed latencies. Longitudinal analysis revealed that most children showed normal or improved cortical maturation after implantation. Conclusion: Cochlear implantation resulted in measureable cortical auditory development for all children with ANSD. Children fitted with CIs under age two years were more likely to show age-appropriate CAEP responses within six months after implantation, suggesting a possible sensitive period for cortical auditory development in ANSD. That CAEP responses were correlated with behavioral outcome highlights their clinical decision-making utility.     

Optical Coherence Angiographic Demonstration of Retinal Changes From Chronic Optic Neuropathies

Glaucoma causes a decrease in peripapillary perfused capillary density on optical coherence tomography (OCT) angiography. However, other chronic optic neuropathies have not been explored with OCT angiography to see if these changes were specific to glaucoma. The authors evaluated OCT angiography in 10 patients who suffered various kinds of chronic optic neuropathies, including optic neuritis and ischaemic optic neuropathy, and found that all optic neuropathies showed a decrease in peripapillary vessel density on OCT angiography, regardless of the aetiology of the optic neuropathy. The peripapillary vessel loss on OCT angiography correlated well with the areas of retinal nerve fibre layer thinning seen on OCT.     

Controversies in neuro-ophthalmology: Steroid therapy for traumatic optic neuropathy

Background:There is an increase in the incidence of traumatic optic neuropathy (TON) due to increasing urbanization and rapid spurt in the number of motor vehicles on the road. Despite early presentation and ease of diagnosis the visual outcomes in TON are still limited. There is also significant confusion about the timing, dose and efficacy of steroid treatment in its management.Purpose:To provide a clinical update of the pros and cons of steroid therapy for TON.Design:The paper is a retrospective review of the currently available literature in the English language indexed in PubMed.Methods:A PubMed search was conducted by the authors using the following terms: Traumatic optic neuropathy, megadose, steroids, methylprednisolone. Relevant original articles, review articles, and case reports related to the topic of discussion were evaluated and discussed in the paper.Results:There is no prospective randomized control trial evaluating the effect of steroids in TON. There are varying reports on the effect of steroid therapy from significant improvement to no difference compared to observation.Conclusion:The decision to give steroids to patients with TON has to be on an individual case to case basis and must involve informed consent from the patient. There are documented advantages and disadvantages of steroid therapy and a prospective, randomized, controlled trial is necessary comparing steroids, surgery and observation before definitive management can be evolved.     

Ultrasound and neurophysiological correlation in common fibular nerve conduction block at fibular head

ObjectiveUltrasound (US) and neurophysiological examination are useful tools in the evaluation of common fibular mononeuropathy. There is only a report comparing US and electrophysiological parameters in patients with common fibular nerve (CFN) conduction block at fibular head. We investigated the correlation between US and neurophysiologic findings in this condition.MethodsWe retrospectively reviewed patients with CFN assessed in our lab during last 2 years. Each patient underwent to clinical, neurophysiological and ultrasound evaluations. Cross sectional area (CSA) of CFN at fibular head was assessed.ResultsTwenty-four patients were included. Motor nerve conduction study showed a reduction of distal compound muscle action potential (CMAP) amplitude in 10 patients (mean 1.3 mV). US showed an increased CSA in 10 patients. Statistical analysis revealed a strong correlation between the increased CSA and the CMAP reduction of CFN.ConclusionOur data suggest that usually US examination is normal in CFN conduction block at fibular head. However the association with axonal damage is frequently accompanied by an increase of CSA.SignificanceUltrasound evaluation may represent a powerful diagnostic/prognostic tool in cases with CPN conduction block at fibular head because it usually shows normal pattern in pure conduction block and increase of CSA in associated axonal damage.     

Linezolid-induced optic neuropathy

Many systemic antimicrobials have been implicated to cause ocular adverse effects. This is especially relevant in multidrug therapy where more than one drug can cause a similar ocular adverse effect. We describe a case of progressive loss of vision associated with linezolid therapy. A 45-year-old male patient who was on treatment with multiple second-line anti-tuberculous drugs including linezolid and ethambutol for extensively drug-resistant tuberculosis (XDR-TB) presented to us with painless progressive loss of vision in both eyes. Color vision was defective and fundus examination revealed optic disc edema in both eyes. Ethambutol-induced toxic optic neuropathy was suspected and tablet ethambutol was withdrawn. Deterioration of vision occurred despite withdrawal of ethambutol. Discontinuation of linezolid resulted in marked improvement of vision. Our report emphasizes the need for monitoring of visual function in patients on long-term linezolid treatment.     

The neuroprotective effect of tropisetron on vincristine-induced neurotoxicity

Vincristine (VCR) peripheral neuropathy is a dose-limiting side effect. Several studies have shown that tropisetron, a 5-HT₃ receptor antagonist, exerts anti-inflammatory and immunomodulatory properties. Current study was designed to investigate a suppressive effect of tropisetron on VCR-induced neuropathy and whether this effect exerts through the 5-HT₃ receptor or not.Neuropathy was induced in rats by administration of vincristine (0.5 mg/kg, 3 intraperitoneal injections on alternate days) and in treatment group, tropisetron (3 mg/kg); m-chlorophenylbiguanide (mCPBG), a selective 5-HT₃ receptor agonist (15 mg/kg); tropisetron (3 mg/kg) plus mCPBG (15 mg/kg); granisetron, another selective 5-HT₃ receptor antagonist (3 mg/kg) were administered intraperitoneally 1 h prior to vincristine injection. Hot plate, open field tests (total distance moved, mean velocity and percentage of total duration of the movement) and motor nerve conduction velocity (MNCV) were performed to evaluate the sensory and motor neuropathy. Further, plasma levels of tumor necrosis factor-alpha (TNF-α) and interleukin-2 (IL-2) and the level of TNF-α in sciatic nerve were assessed as well as histological examination.In only VCR-treated rats hot plate latencies were significantly increased, total distance moved, mean velocity, total duration of the movement and sciatic MNCV significantly decreased compared with control. In tropisetron and tropisetron plus mCPBG groups, one injection of tropisetron prior to each VCR injection robustly diminished TNF-α and IL-2 levels, and also prevented mixed sensory-motor neuropathy, as indicated by less mortality rate, better general conditions, behavioral and electrophysiological studies. Moreover, pathological evidence confirmed the results obtained from other findings. But granisetron and mCPBG had no significant effect on the mentioned parameters.In conclusion, these studies demonstrate that tropisetron significantly suppressed VCR-induced neuropathy and could be a neuroprotective agent for prevention of VCR-induced neuropathy via a receptor-independent pathway.