Infantile progressive bulbar palsy with deafness

Amyotrophic Lateral Sclerosis and its Mimics/Variants: A Comprehensive Review

Motor neuron diseases (MNDs) are a debilitating subset of diseases, which result in progressive neuronal destruction and eventual loss of voluntary muscular function. These entities are often challenging to distinguish and accurately diagnose given overlapping clinical pictures and overall rarity. This group of diseases has a high morbidity and mortality rate overall and delineating each type of disease can help guide appropriate clinical management and improve quality of life for patients. Of all MNDs, amyotrophic lateral sclerosis (ALS) is by far the most common comprising 80%-90% of cases. However, other mimics and variants of ALS can appear similar both clinically and radiographically. In this review, we delve into the epidemiological, physiological, neuroimaging, and prognostic characteristics and management of ALS and its most common MND mimics/variants. In doing so, we hope to improve accuracy in diagnosis and potential management for this rare group of diseases.

Brown-Vialetto-Van Laere syndrome: a novel diagnosis to a common presentation

Brown-Vialetto-Van Laere syndrome (BVVLS) or riboflavin transporter deficiency (OMIM 211530) is a rare treatable autosomal recessive neurodegenerative disorder. This condition is associated with progressive pontobulbar palsy. We describe the clinical course of a 16-month-old boy with BVVLS and a novel homozygous mutation from Pakistan. Our patient presented with stridor and respiratory insufficiency. Hearing loss which is the most common sign of this condition was absent, making it an unusual presentation of BVVLS. His examination revealed ptosis and tongue fasciculation. His riboflavin receptor mutational analysis showed the homozygous mutation in the SLC52A3 gene. Per oral riboflavin was administered, and subsequently, he was able to be weaned off the ventilator. Now the child is improving and attaining developmental milestones.

Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2

Childhood onset motor neuron diseases or neuronopathies are a clinically heterogeneous group of disorders. A particularly severe subgroup first described in 1894, and subsequently called Brown-Vialetto-Van Laere syndrome, is characterized by progressive pontobulbar palsy, sensorineural hearing loss and respiratory insufficiency. There has been no treatment for this progressive neurodegenerative disorder, which leads to respiratory failure and usually death during childhood. We recently reported the identification of SLC52A2, encoding riboflavin transporter RFVT2, as a new causative gene for Brown-Vialetto-Van Laere syndrome. We used both exome and Sanger sequencing to identify SLC52A2 mutations in patients presenting with cranial neuropathies and sensorimotor neuropathy with or without respiratory insufficiency. We undertook clinical, neurophysiological and biochemical characterization of patients with mutations in SLC52A2, functionally analysed the most prevalent mutations and initiated a regimen of high-dose oral riboflavin. We identified 18 patients from 13 families with compound heterozygous or homozygous mutations in SLC52A2. Affected individuals share a core phenotype of rapidly progressive axonal sensorimotor neuropathy (manifesting with sensory ataxia, severe weakness of the upper limbs and axial muscles with distinctly preserved strength of the lower limbs), hearing loss, optic atrophy and respiratory insufficiency. We demonstrate that SLC52A2 mutations cause reduced riboflavin uptake and reduced riboflavin transporter protein expression, and we report the response to high-dose oral riboflavin therapy in patients with SLC52A2 mutations, including significant and sustained clinical and biochemical improvements in two patients and preliminary clinical response data in 13 patients with associated biochemical improvements in 10 patients. The clinical and biochemical responses of this SLC52A2-specific cohort suggest that riboflavin supplementation can ameliorate the progression of this neurodegenerative condition, particularly when initiated soon after the onset of symptoms.

Brown-Vialetto-Van Laere syndrome: clinical and neuroradiological findings of a genetically proven patient

The Brown-Vialetto-Van Laere syndrome (BVVLS) is a rare neurological disorder characterized by progressive pontobulbar palsy, sensorineural deafness and mixed spinal and upper motor neuropathy. Mutations in the C20orf54 gene have been linked to the disease and recently we reported the first Italian case of a BVVLS family with an intriguing C20orf54 genotype. However, the pathomechanisms underlying BVVLS are still unknown. Here we present the particular disease course with partial response to immunosuppressive therapy of our BVVLS patient for whom we hypothesize that dysimmune factors may have played a role in disease physiopathology.

The Brown-Vialetto-Van Laere and Fazio Londe syndrome revisited: natural history, genetics, treatment and future perspectives

The Brown-Vialetto-Van Laere syndrome is a rare neurological disorder which may present at all ages with sensorineural deafness, bulbar palsy and respiratory compromise. Fazio-Londe syndrome is considered to be the same disease entity. Recently it was demonstrated that in some patients the disease is caused by mutations in the SLC52A3 gene which encodes the intestinal (hRFT2) riboflavin transporter. In these patients riboflavin deficiency is the cause of the BVVL/FL syndrome and supplementation of riboflavin proved a life saving treatment. Mutations in the SLC52A2 gene and the SLC52A1 (GPR172B) gene, coding for human riboflavin transporters hRFT3 and hRFT1 have been associated with the BVVL syndrome as well. We performed a review of the literature, with emphasis on the natural history and the effects of treatment in these patients. A total of 35 publications were traced reporting on the clinical presentation of 74 patients who presented before age 18. The most prevalent symptoms were bulbar palsy, hearing loss, facial weakness and respiratory compromise. Death was reported in 28 of the 61 untreated patients, with a very low survival in patients presenting before age 4. All 13 patients who were treated with riboflavin survived, with a strong clinical improvement after days to months of treatment in eight patients. Three patients demonstrated a stable clinical course and treatment was stopped early in two patients. Abnormalities in plasma flavin levels and/or plasma acylcarnitine profiles were observed in some but not in all patients, and also patients with normal plasma flavin levels and acylcarnitine profiles demonstrated a striking clinical improvement on riboflavin supplementation. It is now clear that proper diagnosis requires mutation analysis of all three transporter genes and treatment should be started immediately without first awaiting results of molecular analysis. Clinical improvement may be rapid or gradual over a period of more than 12 months.

Cochlear Implantation in Brown-Vialetto-Van-Laere syndrome

OBJECTIVE

To report outcomes for the first known cochlear implantation procedures in two patients with Brown-Vialetto-Van-Laere syndrome.

PATIENTS

Two adult patients (a brother and sister) with post-lingual sensorineural deafness associated with Brown-Vialetto-Van-Laere syndrome. The female patient presented with a milder form of the syndrome.

INTERVENTION

Cochlear implantation.

MAIN OUTCOME MEASURE

Post-implantation speech discrimination scores.

RESULTS

Auditory evoked potential testing suggested pathological changes in both patients' cochleae, auditory nerves, brainstem and (probably) central auditory pathways. In the male patient, despite implantation of the better ear, the Bamford-Kowal-Bench sentence score was zero at 21 months post-implantation. In the female patient, Bamford-Kowal-Bench sentence scores at six months post-implantation were 25 per cent in quiet and 3 per cent in noise.

CONCLUSION

These poor clinical outcomes appear to be related to retrocochlear and probable central auditory pathway degeneration.

Brown-Vialetto-Van Laere syndrome

The Brown-Vialetto-Van Laere syndrome (BVVL) is a rare neurological disorder characterized by progressive pontobulbar palsy associated with sensorineural deafness. Fifty-eight cases have been reported in just over 100 years. The female to male ratio is approximately 3:1. The age of onset of the initial symptom varies from infancy to the third decade. The syndrome most frequently presents with sensorineural deafness, which is usually progressive and severe. Lower cranial nerve involvement and lower and upper motor neuron limb signs are common neurological features. Other features include respiratory compromise (the most frequent non-neurological finding), limb weakness, slurring of speech, facial weakness, and neck and shoulder weakness. Optic atrophy, retinitis pigmentosa, macular hyperpigmentation, autonomic dysfunction, epilepsy may occur. The etiopathogenesis of the condition remains elusive. Approximately 50% of cases are familial, of which autosomal recessive is suggested. The remaining cases are sporadic. The diagnosis is usually based on the clinical presentation. Investigations (neurophysiological studies, magnetic resonance imaging of the brain, muscle biopsy, cerebrospinal fluid examination) are done to exclude other causes or to confirm the clinical findings. The differential diagnoses include the Fazio-Londe syndrome, amyotrophic lateral sclerosis, Nathalie syndrome, Boltshauser syndrome and Madras motor neuron disease. Treatment with steroids or intravenous immunoglobulin may result in temporary stabilization of the syndrome. However, the mainstays of management are supportive and symptomatic treatment, in particular assisted ventilation and maintenance of nutrition via gastrostomy. The clinical course of BVVL is variable and includes gradual deterioration (almost half of cases), gradual deterioration with stable periods in between (a third of cases) and deterioration with abrupt periods of worsening (just under a fifth of cases). After the initial presentation, one third of patients survive for ten years or longer.

Severe sleep-disordered breathing in a patient with Brown–Vialetto–Van Laere syndrome: Polysomnographic findings

Brown-Vialetto-Van Laere (BVVL) syndrome is a rare disorder with clinical features that include progressive bilateral sensorineural deafness and a variety of cranial nerve impairments. Respiratory compromise has been observed in most familial and sporadic cases; however, few studies have been published regarding sleep-disordered breathing in this syndrome. We report the unique case of a 16-year-old girl with the clinical features of BVVL syndrome who presented with bilateral sensorineural hearing loss and then progressively developed paralysis of the 7th and 9th-12th cranial nerves. More importantly, she presented with the unusual feature of severe sleep-disordered breathing. A polysomnographic study showed evidence of dominant central sleep apnea, and the majority of apneic episodes more likely occurred in stage 2 during NREM sleep. The central sleep apnea was associated with rapid respiratory deterioration and death. This report raises the fact that a patient with BVVL syndrome may present with severe sleep-disordered breathing as a life-threatening condition, which emphasizes the need for greater attention to the early detection of potential sleep-disordered breathing in these afflicted with the BVVL syndrome for optimal clinical management.

A Brazilian family with Brown-Vialetto-van Laere syndrome with autosomal recessive inheritance

We report the first Brazilian family with Brown-Vialetto-van Laere syndrome. The presence of consanguineous marriages and illness affecting three sisters and one niece support an autosomal recessive transmission. The age at onset of the illness ranged from 12 to 20 years old. The time interval between hearing loss and involvement of other cranial nerves varied from 3 to 12 years. MRI demonstrated bulbar atrophy and also high intensity signal at T2 weighted and fluid attenuated inversion recovery (FLAIR) sequences.

Pontobulbar palsy and neurosensory deafness (Brown-Vialetto-van Laere syndrome) with hyperintense brainstem nuclei on magnetic resonance imaging: new finding in three siblings

Three siblings (one boy and two girls) with Brown-Vialetto-van Laere syndrome are reported. A peculiar feature of onset with hearing loss in a patient with multiple cranial nerve palsies and a positive family history suggests this diagnosis. In our family, an autosomal recessive mode of inheritance was seen. In addition, we observed that early onset was associated with rapid deterioration and death. Optic nerve involvement and hyperintensity of the brainstem nuclei on magnetic resonance imaging (MRI) are two new features described in this report.

Clinical features and neurophysiological follow-up in a case of Brown-Vialetto-Van Laere syndrome

Brown-Vialetto-Van Laere syndrome is a rare disease of unknown origin commonly considered as part of the large group of motor neuron diseases. The course is quite variable: it may be quickly fatal or protracted, with relapsing phases followed by periods of arrest and even partial improvement. We describe a case of Brown-Vialetto-Van Laere syndrome with strong family history for sensorineural hearing impairment. The patient came to our medical attention for severe respiratory failure and leg weakness. The clinical conditions partially improved with recovery of spontaneous respiration and mild increase in muscle strength. The neurophysiological studies performed on our patient showed evidence of nerve damage with subsequent improvement. Our study raises the possibility that the disorder is due to primary nerve damage, which can better justify the intermittent course of the disease, the partial clinical regression and the neurophysiological improvement, never detected in typical motor neuron disorders.

Recording click-evoked myogenic potentials (CEMPs) with a setup for brainstem auditory evoked potentials (BAEPs)

AIM OF THE STUDY

Click-evoked myogenic potentials (CEMPs) originate in the sternocleidomastoid (SCM) muscle through a reflex loop involving the sacculus and the vestibular nerve. In this study we suggest that they can be picked up from the mastoid reference used for auditory evoked potential (AEP) recording by using standard filters for brainstem AEPs (BAEPs). They consist of a P13-N20 complex.

METHODS

Fifty normal subjects were investigated. Recordings were performed with the same setting as that used for conventional BAEPs but without artifact rejection and using a wide time window (100 ms). Unilateral auditory stimulations were used. All acquisitions were performed in both sitting and supine positions. In nine subjects CEMPs and BAEPs were simultaneously recorded at both earlobe and both SCM muscles.

RESULTS

In all subjects, a CEMP P13-N20 component could be evidenced in sitting, but not in supine position at both the ipsilateral earlobe and the ipsilateral SCM muscle. Its latency was 0.7 ms lower at the earlobe. It obeyed the same relationship to stimulus intensity at both earlobe and SCM muscle.

CONCLUSION

These results demonstrate the possibility to get simultaneous information on the brainstem auditory pathways and on a reflex probably mediated through the sacculus and the vestibular nerve. Further studies on patients with selective vestibular nerve impairment should be conducted to confirm the clinical utility of this approach.

Brown-Vialetto-Van Laere syndrome; variability in age at onset and disease progression highlighting the phenotypic overlap with Fazio-Londe disease

We report four siblings showing features of a pontobulbar palsy, a mixed spinal and upper motor neuropathy and variable deafness. The observation of affected males and females born to consanguineous first cousin parents suggests autosomal recessive inheritance. Two children presented in the first 16 months of life with stridor and died of respiratory failure by the age of 2 years. Hearing loss was not apparent in these infants. In contrast, 2 further siblings developed a bulbar palsy in their sixth year followed by the onset of deafness and features of an anterior horn neuropathy with corticospinal tract involvement. They exhibited a relatively slow but relentless decline over a period of several years. These cases highlight the phenotypic overlap of Brown-Vialetto-Van Laere syndrome with Fazio-Londe disease. Rather than representing two separate disorders, our findings suggest the possibility of a single disease entity which may usefully be considered a form of juvenile amyotrophic lateral sclerosis.