Friedreich's ataxia: clinical and molecular study of 25 Brazilian cases

The importance of central auditory evaluation in Friedreich's ataxia

Objective To assess central auditory function in Friedreich's ataxia. Methods A cross-sectional, retrospective study was carried out. Thirty patients underwent the anamnesis, otorhinolaryngology examination, pure tone audiometry, acoustic immittance measures and brainstem auditory evoked potential (BAEP) assessments. Results The observed alterations were: 43.3% in the pure tone audiometry, bilateral in 36.7%; 56.6% in the BAEP test, bilateral in 50%; and 46.6% in the acoustic immittance test. There was a significant difference (p < 0.05) in the comparison between the tests performed. Conclusion In the audiological screening, there was a prevalence of the descending audiometric configuration at the frequency of 4kHz, and absence of the acoustic reflex at the same frequency. In the BAEP test, there was a prevalence of an increase of the latencies in waves I, III and V, and in the intervals of interpeaks I-III, I-V and III-V. In 13.3% of the patients, wave V was absent, and all waves were absent in 3.3% of patients.

Otoneurological findings prevalent in hereditary ataxias

Objective To describe and compare the vestibular findings most evident among the hereditary ataxias, as well as correlate their clinical features with the nervous structures affected in this disease. Methods Seventy-five patients were evaluated and underwent a case history, otorhinolaryngological and vestibular assessments. Results Clinically, the patients commonly had symptoms of gait disturbances (67.1%), dizziness (47.3%), dysarthria (46%) and dysphagia (36.8%). In vestibular testing, alterations were predominantly evident in caloric testing (79%), testing for saccadic dysmetria (51%) and rotational chair testing (47%). The presence of alterations occurred in 87% of these patients. A majority of the alterations were from central vestibular dysfunction (69.3%). Conclusion This underscores the importance of the contribution of topodiagnostic labyrinthine evaluations for neurodegenerative diseases as, in most cases, the initial symptoms are otoneurological; and these evaluations should also be included in the selection of procedures to be performed in clinical and therapeutic monitoring.

Otoneurological Abnormalities in Patients with Friedreich's Ataxia

Introduction Friedreich's ataxia is a neurodegenerative disease and progressive by nature. It has autosomal recessive inheritance and early onset in most cases. Nystagmus and hearing loss (in some cases) make up some of the common symptoms seen in this disorder.

Objective The objective of this study is to examine vestibular disorders in patients with Friedreich ataxia.

Methods We conducted a retrospective cross-sectional study. We evaluated 30 patients with ages ranging from six to 72 years (mean age of 38.6 ( ±  14.7). The patients underwent the following procedures: anamnesis, ENT, and vestibular evaluations.

Results Clinically, the patients commonly had symptoms of incoordination of movement (66.7%), gait disturbances (56.7%), and dizziness (50%). In vestibular testing, alterations were predominantly evident under caloric testing (73.4%), gaze nystagmus testing (50.1%), rotational chair testing (36.7%), and optokinetic nystagmus testing (33.4%). The presence of alterations occurred under examination in 90% of subjects, with the majority occurring in those with central vestibular dysfunction (70% of the examinations).

Conclusion The most evident neurotological symptoms were incoordination of movement, gait disturbances, and dizziness. Alterations in vestibular examinations occurred in 90% of patients, mostly in the caloric test, with a predominance of deficient central vestibular system dysfunction.

Clinical heterogeneity of recessive ataxia in the Mexican population

Approximately 75% of Indo-European patients with recessive ataxia are homozygous for frataxin gene (FXN) mutations and have either typical or atypical Friedreich ataxia (FRDA). Our previous analysis of 134 Mexican Mestizo recessive ataxia patients showed that FRDA is relatively uncommon in the Mexican population (10.4%). This article reports the evaluation of the phenotypes of these patients. Over half of the patients with clinical diagnostic criteria for FRDA did not carry FXN mutations, constituting a "FRDA-like" phenotypic subgroup. Analysis of non-FRDA patients revealed a subgroup with early onset recessive cerebellar ataxia and cognitive deficit. These two phenotypic subgroups accounted for approximately 60% of all patients, indicating that the cause for recessive ataxia in the Mexican population is distinct from other populations and remains largely unknown.