A Novel PTRH2 Gene Mutation Causing Infantile-onset Multisystem Neurologic, Endocrine, and Pancreatic Disease in a Bahraini Patient

Infantile-onset multisystem neurologic, endocrine, and pancreatic disease (IMNEPD) is a rare autosomal recessive multisystemic disease with a prevalence of < 1/1 000 000. The wide spectrum of symptoms and associated diseases makes the diagnosis of this disease particularly challenging. Here, we report a 12-year-old Bahraini male who presented with the core clinical features of IMNEPD including intellectual disability, global developmental delay, sensorineural hearing loss, endocrine dysfunction, and exocrine pancreatic insufficiency. The diagnosis was confirmed by genetic testing using whole exome sequencing. This is the first reported case of IMNEPD from Bahrain and was found to have a novel homozygous peptidyl-tRNA hydrolase 2 (PTRH2) gene mutation (NM_001015509.2: c.370del p.(Glu124Lysfs*4)). Moreover, we conducted an extensive literature review with an emphasis on the variable clinical spectrum and genotypes of previously reported patients in comparison to our case.

GJB2: Frequency of the Less Common Variants in a Sample of the Portuguese Population

INTRODUCTION

Sequence variants in the GJB2 gene account for up to 50% of cases of non-syndromic sensorineural hearing loss in the Caucasian population. In this study, we report the frequency of the less common variants of the GJB2 gene in a Portuguese sample and compare these frequencies with those of a group of hearing-impaired patients.

MATERIAL AND METHODS

In order to select the less common GJB2 variants, 147 hearing-impaired patients followed in Centro Hospitalar Universitário de São João were evaluated. Afterwards, the presence of those variants was tested in 360 individuals from Generation 21.

RESULTS

The patient assessment enabled the selection of 11 GJB2 variants. Of those, 10 were investigated in Generation 21 participants, with only four being detected, in heterozygosity: p.Phe83Leu, p.Arg127His, p.Val153Ile and p.Asn206Ser, with the allelic frequencies (95% confidence interval) of 0.14% (0.01% - 0.87%), 0.28% (0.01% - 1.08%), 0.97% (0.43% - 2.04%) and 0.14% (0.01% - 0.88%), respectively. Two variants, p.Val37Ile and p.Val95Met, were more frequent in the patients' group with statistical significance.

DISCUSSION

Our results allow for the p.Arg127His and p.Val153Ile variants to comply with polymorphism criteria and support the pathogenicity of p.Val37Ile and p.Val95Met variants. Moreover, two cases of moderate hearing loss were explained by the p.Val37Ile/p. Asn206Ser genotype, substantiating both the pathogenicity of such variants and the hypothesis that compound heterozygosity with p.Ans206Ser is associated with mild-moderate genotypes.

CONCLUSION

Understanding the role of the variants is essential in order to provide genetic counselling to patients and their families. We explored a set of uncommon GJB2 variants that comprised 12% of the hearing-impaired patients in this study, supporting the relevance of their description.

Incomplete Partition Type III: Computed Tomography Features and Cochlear Implantation Complications

In this case report, we review a male child who presented with severe bilateral hearing loss. Preoperative high-resolution computed tomography (HRCT) evaluation facilitated the initial diagnosis of the disease, which revealed typical findings of cochlear incomplete partition type III anomaly (IP-III), surgical planning, and cochlear implant selection to avoid possible complications. The child underwent cochlear implantation, which resulted in gushing and misplacement of the electrodes into the internal auditory canal (IAC) as postoperative complications. Postoperative imaging was used to determine the position of the implant and to assess the complications. The child’s postoperative X-ray revealed misplacement of the cochlear implant, the extent of which was further assessed by a HRCT scan for preplanning the revision surgery and electrode selection. Following the revision surgery, a further HRCT scan confirmed proper implantation and ruled out any further complications.

Radiological measurement of cochlear dimensions in cochlear hypoplasia and its effect on cochlear implant selection

OBJECTIVE

To determine the effect of cochlear dimensions on cochlear implant selection in cochlear hypoplasia patients.

METHODS

Temporal bone computed tomography images of 36 patients diagnosed with cochlear hypoplasia between 2010 and 2016 were retrospectively reviewed and compared with those of 40 controls without sensorineural hearing loss.

RESULTS

Basal turn length and mid-modiolar height were significantly lower in the cochlear hypoplasia patients with subtypes I, II and III than in the control group (p < 0.001). Mid-scalar length was significantly shorter in subtype I-III patients as compared with the control group (p < 0.001). In addition, cochlear canal length (measured along the lateral wall) was significantly shorter in subtype I-IV patients than in the control group (subtypes I-III, p < 0.001; subtype IV, p = 0.002).

CONCLUSION

Cochlear hypoplasia should be considered if basal turn length is less than 7.5 mm and mid-modiolar height is less than 3.42 mm. The cochlear implant should be selected according to cochlear hypoplasia subgroup. It is critically important to differentiate subtype II from incomplete partition type I and subtype III from a normal cochlea, to ensure the most appropriate implant electrode selection so as to optimise cochlear implantation outcomes.

Totally implantable active middle-ear implants: a large, single-surgeon cohort

OBJECTIVES

This study aimed to evaluate hearing outcomes and device safety in a large, single-surgeon experience with the totally implantable active middle-ear implants.

METHODS

This was a retrospective case series review of 116 patients with moderate-to-severe sensorineural hearing loss undergoing implantation of active middle-ear implants.

RESULTS

Mean baseline unaided pure tone average improved from 57.6 dB before surgery to 34.1 dB post-operatively, signifying a mean gain in pure tone average of 23.5 dB (p = 0.0002). Phonetically balanced maximum word recognition score improved slightly from 70.5 per cent to 75.8 per cent (p = 0.416), and word recognition score at a hearing level of 50 dB values increased substantially from 14.4 per cent to 70.4 per cent (p < 0.0001). Both revision and explant rates were low and dropped with increasing surgeon experience over time.

CONCLUSION

This study showed excellent post-operative hearing results with active middle-ear implants with regard to pure tone average and word recognition score at a hearing level of 50 db. Complication rates in this case series were significantly lower with increasing experience of the surgeon. Active middle-ear implants should be considered in appropriate patients with moderate-to-severe sensorineural hearing loss who have struggled with conventional amplification and are good surgical candidates.

Cochlear nerve anomalies in paediatric single-sided deafness - prevalence and implications for cochlear implantation strategies

OBJECTIVE

To determine the prevalence of cochlear nerve anomalies on magnetic resonance imaging in patients with unilateral or bilateral sensorineural hearing loss.

METHODS

A retrospective case series was conducted at a tertiary referral centre. The inclusion criteria were paediatric patients with bilateral or unilateral sensorineural hearing loss, investigated with magnetic resonance imaging. The primary outcome measure was the rate of cochlear nerve hypoplasia or aplasia.

RESULTS

Of the 72 patients with unilateral sensorineural hearing loss, 39 per cent (28 cases) had absent or hypoplastic cochlear nerves on the affected side. Fifteen per cent (11 cases) had other abnormal findings on magnetic resonance imaging. Eighty-four patients had bilateral sensorineural hearing loss, of which cochlear nerve hypoplasia or aplasia was identified only in 5 per cent (four cases). Other abnormal findings were identified in 14 per cent (12 cases).

CONCLUSION

Paediatric patients with unilateral sensorineural hearing loss are more likely to have cochlear nerve anomalies than those patients with bilateral sensorineural hearing loss. This has important implications regarding cochlear implantation for patients with single-sided deafness.

Cochlear nerve canal stenosis and associated semicircular canal abnormalities in paediatric sensorineural hearing loss: a single centre study

OBJECTIVE

This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis.

METHOD

This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated.

RESULTS

Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent).

CONCLUSION

Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

Giant Cell (Temporal) Arteritis with Persistent Bilateral Sensorineural Hearing Loss - A Likely Consequence of Delayed Institution of Glucocorticoid Therapy

Patient: Male, 66

Final Diagnosis: Giant cell arteritis

Symptoms: Hearing loss

Medication: —

Clinical Procedure: —

Specialty: Rheumatology

Factors Affecting the Variation of Maximum Speech Intelligibility in Patients With Sensorineural Hearing Loss Other Than Apparent Retrocochlear Lesions

OBJECTIVES

To examine the relationship between speech intelligibilities among the similar level of hearing loss and threshold elevation of the auditory brainstem response (ABR).

METHODS

The relationship between maximum speech intelligibilities among similar levels of hearing loss and relative threshold elevation of the click-evoked ABR (ABR threshold - pure tone average at 2,000 and 4,000 Hz) was retrospectively reviewed in patients with sensorineural hearing loss (SNHL) other than apparent retrocochlear lesions as auditory neuropathy, vestibular schwannoma and the other brain lesions.

RESULTS

Comparison of the speech intelligibilities in subjects with similar levels of hearing loss found that the variation in maximum speech intelligibility was significantly correlated with the threshold elevation of the ABR.

CONCLUSION

The present results appear to support the idea that variation in maximum speech intelligibility in patients with similar levels of SNHL may be related to the different degree of dysfunctions of the inner hair cells and/or cochlear nerves in addition to those of outer hair cells.