Brown-Vialetto-Van Laere Syndrome
What is Brown-Vialetto-Van Laere syndrome (BVVL)?
Brown-Vialetto-Van Laere syndrome (BVVL) is a type of riboflavin deficiency disorder that causes progressive neurodegeneration. This degeneration causes paralysis of the cranial nerves, which is sometimes referred to as “bulbar palsy,” as well as sensorineural hearing loss.
It should be noted that progressive bulbar palsy without hearing loss is referred to as Fazio-Londe syndrome.
What causes Brown-Vialetto-Van Laere syndrome (BVVL)?
Recently, BVVL has been linked to several genes that cause riboflavin transport deficiency, though the exact gene responsible is still yet to be determined. In addition, most cases of BVVL seem to follow an autosomal recessive inheritance pattern.
What are the symptoms of Brown-Vialetto-Van Laere syndrome (BVVL)?
Onset of BVVL varies from infancy to mid-adulthood. In many cases, children lead a normal life developmentally for years before developing the symptoms of BVVL. With that being said, the first symptom of this condition is sensorineural deafness. After this, the following examples of nerve degeneration develop:
- Vocal cord paralysis
- Droopy eyelids (ptosis)
- Facial, neck, and/or shoulder weakness
- Slurred speech
- Difficulty swallowing (dysphagia)
- Visual difficulty
- Autonomic dysfunction
- Respiratory compromise
How is Brown-Vialetto-Van Laere syndrome (BVVL) diagnosed?
BVVL is diagnosed after a detailed patient and family history and a thorough clinical examination to observe the characteristic symptoms of the disease, namely hearing loss, other cranial nerve palsies, and lower motor neuron limb involvement. Laboratory testing, such as MRI scanning, EMGs, and cerebral spinal fluid analysis can help with this.
Although BVVL shares some similar features with spinal muscular atrophy, the two conditions do not share the same gene mutations and should be distinguished.
To confirm a diagnosis of BVVL, molecular genetic testing should be done to unveil any mutation(s) in one of the BVVL genes or the known riboflavin transporter genes.
What are the available treatments for Brown-Vialetto-Van-Laere syndrome (BVVL)?
Currently, there is no guaranteed effective treatment for BVVL, although there have been reports of success with a new B2 Protocol that could stabilize or even reverse the nerve degeneration in this disease. Even so, this therapy does not seem to work for all patients with BVVL.
In addition to B2 Protocol, steroids and intravenous immunoglobulins could help stabilize patients, but again, these therapies are not guaranteed, so treatment for the most part is symptomatic and supportive. Tracheostomy, assisted ventilation, and gastrostomy are some of these treatment options.