Abnormalities in auditory evoked potentials of 75 patients with Arnold-Chiari malformations types I and II

Abstract

-Objective: To evaluate the frequency and degree of severity of abnormalities in the auditory pathways in patients with Chiari malformations type I and II. Method: This is a series-of-case descriptive study in which the possible presence of auditory pathways abnormalities in 75 patients (48 children and 27 adults) with Chiari malformation types I and II were analyzed by means of auditory evoked potentials evaluation. The analysis was based on the determination of intervals among potentials peak values, absolute latency and amplitude ratio among potentials V and I. Results: Among the 75 patients studied, 27 (36%) disclosed Arnold-Chiari malformations type I and 48 (64%) showed Arnold-Chiari malformations type II. F i f t y -t h re e (71%) of these patients showed some degree of auditory evoked potential abnormalities. Te s t s w e re normal in the remaining 22 (29%) patients. Conclusion: A u d i t o ry evoked potentials testing can be c o n s i d e red a valuable instrument for diagnosis and evaluation of brain stem functional abnormalities in patients with Arnold-Chiari malformations type I and II. The determination of the presence and degree of severity of these abnormalities can be contributory to the prevention of further handicaps in these patients either through physical therapy or by means of precocious corrective surgical intervention.KEY WORDS: Arnold-Chiari malformations type I and type II, auditory evoked potentials.A n o rmalidades nos potenciais evocados auditivos de 75 pacientes com os tipos I e II das malformações de Arnold-Chiari RESUMO -Objetivo: Avaliar a freqüência e grau de comprometimento das vias auditivas em tronco cerebral por meio de potencial evocado auditivo, em pacientes afetados por malformações de Arn o l d -C h i a r i de tipos I e II. Método: Foi efetuado um estudo descritivo de tipo série de casos, sendo selecionados 75 pacientes (48 crianças e 27 adultos) nos quais foi realizada avaliação dos potenciais evocados das vias auditivas, com base à determinação dos valores dos intervalos entre picos de potenciais, da latência absoluta e da razão entre as amplitudes dos potenciais V e I. Resultados: E n t re os 75 pacientes avaliados, 27 (36%) a p resentavam malformações de Arnold-Chiari de tipo I e 48 (64%) apresentavam malformações de tipo II. Em 53 (71%) do total de pacientes os potenciais evocados auditivos mostraram algum grau de anormalidade. Os testes foram normais nos restantes 22 (29%). Conclusão: O potencial evocado auditivo pode ser considerado valioso instrumento para o diagnóstico e avaliação da gravidade das anormalidades funcionais de tronco cerebral em pacientes port a d o res de malformações de Arnold-Chiari de tipo I e II. Esta avaliação pode contribuir de maneira significativa não somente no diagnóstico como também na prevenção de ulter i o res lesões, pela adoção de medidas preventivas, tanto por meio de fisioterapia como por interv e n ç ã o cirúrgica precoce. PALAVRAS-CHAVE: malformação de Arnold-Chiari de tipo I e de tipo II, potenciais evocados auditivos.

Alterações auditivas em recém-nascidos e lactentes com mielomeningocele

“…High brainstem impairments occurred more often in SG1 (11.9%), which explains the increase in the absolute latencies of waves III and V. Diffuse impairment of the auditory pathway occurred in 15.8% of the individuals in SG2 (Figure 2). In a study conducted with 48 patients with ACMII, 36% of the individuals presented low brainstem impairment and 15% of them showed high brainstem impairment (27) , corroborating the findings of the present survey (30.9% and 11.9%). No studies conducted with patients with isolated MMC were found in the literature.…”

“…In SG1, increased absolute latencies of waves III and V and of the interpeak intervals III-V and I-V were observed, which characterize high brainstem impairment. In fact, there is evidence in the literature that 41.7% of patients with ACMII presented prolonged absolute latencies and interpeak intervals (27) .…”

Anomalous development of brain structure and function in spina bifida myelomeningocele

“…Intrinsic brainstem abnormalities and pressure on the brainstem from a crowded posterior fossa and hydrocephalus give rise to a diverse range of symptoms such as headaches, apnea, bradycardia, dysphagia, torticollis, spasticity, and impaired auditory evoked potentials [Wagner et al, 2002;Henriques Filho and Pratesi, 2006;Bowman and McLone, 2010]. Brainstem compression occurs in a third of patients with CII and may be fatal in about a third of these patients [Stevenson, 2004].…”

Sleep disorder: a possible cause of attention deficit in children and adolescents with Chiari malformation type II

“…In contrast, controls showed an increased frequency of obstructive apneas, predominantly caused by airway pathologies, allergic rhinitis being the most common (6/24). The increased frequency of sleep disorder in CM II patients, may be explained by the variable degree of brain stem abnormalities in CM II patients 21,22 , generally involving midbrain, pons and medulla oblongata, where are localized neurons of the respiratory regulation, and neurons of the REM sleep and of the movement control during sleep [23][24][25] . Analyzing these data, it is possible to conclude that sleep disorders are more prone to cause attention deficit than the presence of CM II alone, since in CM II patients without sleep disorders no attention deficit could be detected (Table 4).…”