Sudden Onset Auditory Neuropathy Spectrum Disorder: A Rare Case Report of Brown Vialetto Van Laere Syndrome

Abstract

Brown Vialetto Van Laere syndrome is a rare disorder characterized by progressive pontobulbar palsy with bilateral sensorineural hearing loss and lower cranial nerve palsies. Fifty-eight cases have been reported in the last hundred years. As the most common presenting complaint of this disorder is hearing loss, audiological evaluation plays a vital role in pointing towards and narrowing its diagnosis. We present a case report of a 12-year male child affected by this disorder.

Case Presentation

We report the case of a 12 years male child, who presented with history of diminution of vision in both eyes at the age of 6, which was insidious in onset, painless and non-progressive. Patient experienced difficulty in hearing in both ears for the past year, which was insidious in onset and gradually progressive which led the parents to seek medical opinion. Patient also had difficulty in holding pen and buttoning shirt. Patient is the first-born child to a non-consanguineous marriage and developmentally adequate for age in all domains. Antenatal and birth history didn’t reveal any significant findings.

Clinical evaluation revealed a pattern of neuropathy with cranial nerves 2, 8, 12 and pure motor involvement of bilateral median and ulnar nerves.

Cranial nerve examination

Cranial nerve	Right	Left
1	Normal	Normal
2	Direct and consensual light reflex present RAPD present Visual acuity 1/60	Direct and consensual light reflex present RAPD present Visual acuity 1/60
3,4,5,6,7	Normal	Normal
8	Weber test lateralized to right Rinne test negative PTA – Sensorineural hearing loss	Rinne negative on left PTA – mixed hearing loss
9,10,11	Normal	Normal
12	Normal power Fasciculations present	Normal

He underwent evaluation for vision at multiple hospitals but no definite diagnosis was made and his condition was unchanged. At our hospital he underwent various investigations including genetic analysis.

Genetic analysis revealed the following:

Gene: SLC52A2

Variant: C-401 C > T p Pro134 Leu (depth − 172x)

Exon:3

Homozygous

Classification: VUS

Disease: Brown Vialetto Van Laere syndrome 2

Audiological evaluation was performed and showed.

Right sided sensorineural hearing loss and left mixed hearing loss in Pure Tone Audiometry as shown in Fig. 1. Otoacoustic emissions are present bilaterally. Cochlear microphonics were observed during Brainstem Evoked Response Audiometry (BERA) as shown in Fig. 2. Ophthalmological evaluation revealed a visual acuity of 1/60 in both eyes, Optic disc pallor was present in fundus examination, no evidence of retinitis pigmentosa. Magnetic resonance imagining of brain with spine showed syrinx of 1 mm at C3- C6 level.

Fig. 1.

Pure tone audiometry

Fig. 2.

Brainstem evoked response audiometry with observed Cochlear microphonics

Riboflavin therapy was initiated for the patient, Physiotherapy is being continued and patient is being kept under regular follow up.

Discussion

The Brown Vialetto Van Laere Syndrome, a rare disorder usually presenting as sudden sensorineural hearing loss associated with multiple cranial nerve palsies and respiratory compromise [1]. This was first described by Brown in 1984 and later by Vialetto and van Laere in 1936 and 1966 respectively. This disorder is usually characterized by progressive pontobulbar palsy with female predisposition (3:1 female to male ratio) [2]. The duration between onset of deafness and other symptoms is less in males than in females [3]. Fifty-eight cases have been reported in the last hundred years [2. Patients can present anywhere in between infancy and third decade. The exact cause for this disorder is still elusive, but it is postulated that riboflavin transporter mutations have a significant role in its etiogenesis. Hence it is being managed with high dose riboflavin therapy at present. More than 50% of the cases are familial, which are autosomal recessive in inheritance. Diagnosing the disorder is partly clinical and partly based on other investigations including audiological evaluation, muscle biopsy, neurophysiological studies, imaging such as magnetic resonance imaging and genetic analysis.

Hearing loss in this disorder has the characteristic of auditory neuropathy spectrum disorder. The progression of hearing loss is rapid and most patients have profound hearing loss withing two years of start of hearing loss. Cochlear implants and hearing aids have been tried for some cases but showed limited or no benefit. High dose riboflavin therapy was found to be successful if initiated within one year of start of symptoms [4].

Some patients also present with non-neurological features of which respiratory compromise is the most common. Other non-neurological features include auditory hallucinations, color blindness, diabetes insipidus, delayed puberty, hypertension. Although there are cases where no associated non neurological features were reported [5].

The clinical course of this disease varies from case to case where survival rates are between 5 and 10 years of diagnosis. The people affected by this disorder has a progressive course with or without periods of stabilization in between. The most common cause of mortality is due to respiratory compromise either due to respiratory muscle paralysis or due to infections [4].

Conclusion

Brown Vialetto Van Laere Syndrome is a rare disorder where auditory rehabilitation is difficult. Audiological evaluation in these cases is the first clue to its diagnosis. Both subjective and objective audiological tests help in diagnosis. Although cochlear implantation has success rates than hearing aids, the use of high dose riboflavin therapy is the most accepted mode of management at present.

Author Contribution

All the authors have equally contributed to the case report. VMS is the major contributor in writing the manuscript. HGH, KR participated in writing, editing and data interpretation along with VMS.

Funding

There was no funding required to take up the study.

Data Availability

The datasets during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics Approval and Consent to Participate

The study was taken after obtaining an Ethics committee approval from the Institution of Ethics Committee, JIPMER, Pondicherry, India.

Consent for Publication

Written informed consent for publication of their clinical details and/or clinical images was obtained from the patient. A copy of the consent form is available for review by the Editor of this journal.

Competing Interests

The authors declare that they have no competing interests.