Progressive Pontobulbar Palsy Research Articles

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

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.

Vitamin responsive conditions in pediatric neurology

Vitamin responsive conditions can be either due to inherited defects in the metabolic pathways resulting in vitamin dependency or due to acquired deficiency states. Due to widespread malnutrition and predominantly vegetarian population in India, vitamin deficiency state is quite common and early identification is essential. Inherited defects, if treated earlier, lead to reduced morbidity and mortality and improvement in long-term neurocognitive outcomes. Various vitamin responsive conditions in pediatric neurology shall be discussed in this review. Infantile presentation of thiamine deficiency results in beriberi, and in adults, it leads to Wernicke’s encephalopathy and Korsakoff psychosis. Biotin thiamine-responsive basal ganglia disease is a defect of thiamine transporter 2, which leads to neuroregression and characteristic neuroimaging features of basal ganglia involvement, it responds to high doses of biotin and thiamine. Riboflavin is an enzyme involved in mitochondrial energy synthesis and is supplemented in various mitochondrial metabolic conditions. Brown-Vialetto-Van Laere syndrome is progressive pontobulbar palsy caused by defect in riboflavin transporters responsive to high doses of riboflavin. Pyridoxine responsive epilepsy presents with pharmacoresistant seizures in neonatal or early infantile age, biotinidase deficiency also presents with similar neurological manifestations, but typical cutaneous symptoms of rash and seborrheic dermatitis also occur. Both are epileptic encephalopathies and any infant presenting with epilepsy not responding to conventional AEDs must be given a trial of pyridoxine, biotin, and folinic acid. Vitamin B12 responsive conditions can include deficiency states, such as those manifesting with peripheral neuropathy and the syndrome of infantile tremor syndrome (developmental delay or regression, tremors, and megaloblastic anemia) as well as inherited disorders of homocysteine and cobalamin metabolism. These disorders are differentiated on the basis of clinical phenotype and laboratory parameters (serum B12, homocysteine levels, methylmalonic acid levels, etc.). Infantile tremor syndrome responds drastically to mega doses of Vitamin B12 and other multivitamins. Vitamin E deficiency causes ataxia with Vitamin E deficiency, other vitamins which can neurological symptoms include Vitamin C (pseudoparalysis) and Vitamin K (central nervous system bleeds). It is imperative for a practicing pediatrician to be well versed with these conditions, as these are potentially treatable conditions.

Mitochondrial and Peroxisomal Alterations Contribute to Energy Dysmetabolism in Riboflavin Transporter Deficiency.

Riboflavin transporter deficiency (RTD) is a childhood-onset neurodegenerative disorder characterized by progressive pontobulbar palsy, sensory and motor neuron degeneration, sensorineural hearing loss, and optic atrophy. As riboflavin (RF) is the precursor of FAD and FMN, we hypothesize that both mitochondrial and peroxisomal energy metabolism pathways involving flavoproteins could be directly affected in RTD, thus impacting cellular redox status. In the present work, we used induced pluripotent stem cells (iPSCs) from RTD patients to investigate morphofunctional features, focusing on mitochondrial and peroxisomal compartments. Using this model, we document the following RTD-associated alterations: (i) abnormal colony-forming ability and loss of cell-cell contacts, revealed by light, electron, and confocal microscopy, using tight junction marker ZO-1; (ii) mitochondrial ultrastructural abnormalities, involving shape, number, and intracellular distribution of the organelles, as assessed by focused ion beam/scanning electron microscopy (FIB/SEM); (iii) redox imbalance, with high levels of superoxide anion, as assessed by MitoSOX assay accompanied by abnormal mitochondrial polarization state, evaluated by JC-1 staining; (iv) altered immunofluorescence expression of antioxidant systems, namely, glutathione, superoxide dismutase 1 and 2, and catalase, as assessed by quantitatively evaluated confocal microscopy; and (v) peroxisomal downregulation, as demonstrated by levels and distribution of fatty acyl β-oxidation enzymes. RF supplementation results in amelioration of cell phenotype and rescue of redox status, which was associated to improved ultrastructural features of mitochondria, thus strongly supporting patient treatment with RF, to restore mitochondrial- and peroxisomal-related aspects of energy dysmetabolism and oxidative stress in RTD syndrome.

Remarkable motor recovery after riboflavin therapy in adult-onset Brown—Vialetto—Van Laere syndrome

The clinical diagnosis of Brown—Vialetto—Van Laere syndrome in this woman with rapidly progressive pontobulbar palsy led to empirical high-dose oral riboflavin (1200 mg/day) therapy. This resulted in a dramatic improvement...

Motor neuron disease in a young female, Madras pattern or Brown-Vialetto Van Laere syndrome? - A diagnostic dilemma

<p class="abstract">We report a case of a 14 year old female patient with progressive ponto-bulbar palsy, bilateral deafness and distal muscle weakness with wasting. This pattern is seen in Brown-Vialetto-Van Laere which is an extremely rare neurological disorder of unknown etiology with less than 80 cases being reported till date. The syndrome was first described in 1894 by Brown and subsequently by Vialetto in 1936 and Van Laere in 1966. A similar pattern is noted in the Madras form of motor neuron disease which is seen in South India. With the available literature and data it's difficult to differentiate between these entities.</p>

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.

Riboflavin transporter 3 involvement in infantile Brown-Vialetto-Van Laere disease: two novel mutations

BackgroundBrown-Vialetto-Van Laere (BVVL) syndrome is a rare disorder characterised by progressive pontobulbar palsy and sensorineural deafness. Causative mutations in genes encoding human riboflavin transporter 2 (hRFT2) and 3 (hRFT3) have...

Support your local paediatric neurophysiologist

SIR–The discovery that high-dose riboflavin can treat Brown– Vialetto–Van Leare syndrome is perhaps one of the most exciting developments in paediatric neurology over recent years. This condition, like Fazio–Londe syndrome with which it shares some features, was regarded as an untreatable and relentlessly progressive condition. There have been a series of papers which suggest early treatment may reverse the deterioration although the diaphragm does seem to be stubbornly resistant. 1–3 It was therefore with interest that I read the article by Anand et al. describing a 22-month-old female who responded to high-dose riboflavin. 4 In their concluding comments the authors state that ‘… an early genetic diagnosis in patients presenting with progressive ponto-bulbar palsy with or without sensorineural deafness will enable early institution of therapy and reversal of symptom progression, leading to a better prognosis.’ I do not disagree with the sentiment, but feel that perhaps they have not emphasized the importance of clinical neurophysiology and, in particular, electromyography (EMG) in the early diagnosis of these cases. The studies done by their neurophysiologist were excellent. This neurophysiologist even succeeded with voluntary single-fibre EMG in a 22-monthold child, which is an achievement on its own. Our experience is that there are increasing numbers of referrals of children with suspected bulbar palsy and it is not at all uncommon for a discovery of neurogenic change to be made. In fact, in one of our recent cases of Brown–Vialetto–Van Laere syndrome the discovery of definite neurogenic change in the tongue antedated by several months clinical confirmation of abnormalities in that region. EMG is exquisitely sensitive to denervation and particularly chronic denervation, and it is quite feasible for these changes to be manifest on EMG before clinical appearances such as the tongue fasciculation or wasting confirm the suspicions. It is well-known that effective reinnervation may compensate for muscle fibres which lose their nerve supply with atrophy only occurring when that capacity is exhausted. We are very early on in discovering an effective treatment for this condition but there do appear to be indications that if instituted at the earliest possible point in the disease, rather like pyridoxine dependency, near normalization of the metabolic abnormality may be possible. From what has been said above, EMG of the tongue may give the first indication of abnormality and clinicians should think of this when they have a suspicion of Brown–Vialetto–Van Laere syndrome and encourage their neurophysiologist to assist them. The technique is easily within the reach of any competent clinical neurophysiologist, and if combined with screening for deafness could provide a very quick and effective way to pick up these children early. Otherwise, a great number of children are going to be screened genetically and metabolically with little benefit.

Brown–Vialetto–van Laere and Fazio–Londe overlap syndromes: A clinical, biochemical and genetic study

Brown-Vialetto-van Laere (BVVL) and Fazio-Londe (FL) are rare and clinically overlapping motor neurons syndromes. Recently BVVL has been associated with mutations in C20orf54/hRFT2 and defective riboflavin transport. We compared clinical and laboratory features of 6 patients (age range 11-17 years), with features of BVVL and FL overlap syndromes. Patients were assessed as following: blood levels of riboflavin and redox status, electrophysiological, neuroradiological and pulmonary studies, ALS functional rating scale and molecular genetic analysis. Two patients manifested deafness at ages of 3 and 10 years, and developed later subacute progressive ponto-bulbar palsy. A third patient markedly improved after intravenous immunoglobulins (IVIG), but then relapsed remaining unresponsive to treatment; he was not deaf although had abnormal auditory evoked responses (BAERs). The remaining 3 patients had no deafness, although likewise manifested subacute progressive ponto-bulbar palsy. We found hRFT2 mutations in 3/6 patients manifesting deafness or abnormal BAERs. No patient had reduced riboflavin blood levels. However, on riboflavin supplementation (10mg/kg/day) the most severely affected BVVL patient stopped progression of symptoms following 8 months of treatment. BVVL and FL are severe progressive diseases with overlapping symptoms although only hRFT2 mutated patients manifest deafness. Riboflavin supplementation seems to stabilize and improve progression of the disease.

Brown‐Vialetto‐Van Laere and Fazio Londe syndrome is associated with a riboflavin transporter defect mimicking mild MADD: a new inborn error of metabolism with potential treatment

We report on three patients (two siblings and one unrelated) presenting in infancy with progressive muscle weakness and paralysis of the diaphragm. Metabolic studies revealed a profile of plasma acylcarnitines and urine organic acids suggestive of a mild form of the multiple acyl-CoA dehydrogenation defect (MADD, ethylmalonic/adipic acid syndrome). Subsequently, a profound flavin deficiency in spite of a normal dietary riboflavin intake was established in the plasma of all three children, suggesting a riboflavin transporter defect. Genetic analysis of these patients demonstrated mutations in the C20orf54 gene which encodes the human homolog of a rat riboflavin transporter. This gene was recently implicated in the Brown-Vialetto-Van Laere syndrome, a rare neurological disorder which may either present in infancy with neurological deterioration with hypotonia, respiratory insufficiency and early death, or later in life with deafness and progressive ponto-bulbar palsy. Supplementation of riboflavin rapidly improved the clinical symptoms as well as the biochemical abnormalities in our patients, demonstrating that high dose riboflavin is a potential treatment for the Brown-Vialetto-Van Laere syndrome as well as for the Fazio Londe syndrome which is considered to be the same disease entity without the deafness.

Brown-Vialetto-Van Laere Syndrome, a Ponto-Bulbar Palsy with Deafness, Is Caused by Mutations in C20orf54

Brown-Vialetto-Van Laere syndrome is a rare neurological disorder with a variable age at onset and clinical course. The key features are progressive ponto-bulbar palsy and bilateral sensorineural deafness. A complex neurological phenotype with a mixed picture of upper and lower motor neuron involvement reminiscent of amyotrophic lateral sclerosis evolves with disease progression. We identified a candidate gene, C20orf54, by studying a consanguineous family with multiple affected individuals and subsequently demonstrated that mutations in this gene were the cause of disease in other, unrelated families.

Pontobulbar palsy and sensorineural deafness (Brown-Vialetto-van Laere syndrome): The first case from Libya

We report the first case of Brown-Vialetto-van Laere syndrome from Libya. A 27-year-old female patient with progressive pontobulbar palsy, sensorineural deafness and generalized muscle weakness is described. Although she was born to consanguineous first cousin parents, she was the only one affected among five brothers and six sisters. The first symptoms appeared at the age of 18 years with tinnitus, weakness and unsteadiness that progressed over the course of a few weeks to deafness, blurring of vision, dysphagia, and dysarthria. Over the last nine years her symptoms progressed slowly, although interrupted with periods of rapid deterioration. Fifty-eight cases have been reported since the first case was described in 1894.

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.