Rare Variant of Bartter Syndrome with Sensorineural Deafness

Bartter syndrome is an inherited renal tubular disorder characterized by hypokalemia, hypochloremic metabolic alkalosis, hyperreninemia, hyper-prostaglandinism, normal blood pressure, with increased urinary loss of sodium, chloride, potassium, calcium and prostaglandins. There are five known type of Bartter syndrome, out of which type 4 and 5 are very rare. We are presenting here a case of Bartter syndrome with sensorineural hearing loss.


Introduction
B ar er syndrome is a rare inherited defect in the thick ascending limb of the loop of Henle 1 .It is characterized by hypokalemia, metabolic alkalosis and normal to low blood pressure.Bar er syndrome can be divided into diff erent subtypes on the basis of gene involved viz type 1-neonatal Bar er's syndrome, type 2 -neonatal Bar er's syndrome, type 3 -classic Bar er's syndrome, type 4 -Bar er's syndrome with sensorineural deafness, type 5 -Bar er's syndrome associated with autosomal dominant hypocalcemia 2 .A closely associated disorder, Gitelman's syndrome is a primary renal tubular hypokalemic metabolic alkalosis with hypocalciuria and magnesium defi ciency 3 and can be easily dis nguished from Bar er's syndrome on the basis of urinary calcium levels 4 .

The Case
A 2 years old male was admi ed to our hospital with complaints of vomi ng, increased thirst and urina on for 2 days.Parents also complained about delayed speech and the child was not able to speak even monosyllabous words.No other family member had similar illness and there was no history of parental consanguinity.
On examina on, the child was of average built with normal motor milestones but defec ve language development as only cooing sounds were present.The child was not responding to sound.Blood pressure was 76/60 mm Hg and pulse rate was 136 per minute.Dehydra on was present.There was hypothermia but sensorium was normal.Systemic examina on was within normal limit.On audiometric assessment 120db tones of various frequencies were given by head phone which did not elicit any response including eye blink or head turning sugges ng B/L severe to profound hearing loss.
Pa ent was treated with indomethacin, oral magnesium and potassium supplementa on.Pa ent symptoms improved and discharged and referred to higher center for audiological rehabilita on.

Discussion
Bar er's syndrome is uncommon inherited abnormali es of ion channels in the thick ascending limb of the loop of Henle.It is characterized by hypercalciuria and nephrocalcinosis, and may be associated with maternal polyhydramnios, premature birth and low birth weight, and early onset of symptoms, including vomi ng, Polydipsia, dehydra on with hypotension, muscle weakness, paresthesias, and developmental delay 5 .
We report here a case of two year old boy with Bar er syndrome with bilateral sensorineural deafness.More than hundred cases of Bar er syndrome were iden fi ed.To our best knowledge this is the third case of Bar er syndrome with bilateral sensorineural deafness from the Indian community 6 .The infan le BS with sensorineural deafness, or type IV BS, is linked to autosomal recessive muta ons in the BSND gene, located on chromosome 1p31 and coding Bar n protein 7,8 .Bar n protein is an essen al subunit of the ClC-Ka and ClC-Kb chloride channels and is expressed in tubular segments spanning from the thick ascending limb to cor cal collec ng ducts in the kidney, whereas in the inner ear, it is expressed in potassium-secre ng epithelial cells 7 .The underlying mechanisms of the saltlosing renal tubular disorder and of the related deafness have been a ma er of interest for pediatricians, general prac oners, nephrologists, and otolaryngologists.In regard to hearing loss, the latest studies showed that sensorineural hearing loss in infan le BS is caused by the loss of outer hair cells and by a decrease in the mechanoelectrical transduc on current of inner hair cells due to a drop in the endocochlear poten al 9. Fluid and electrolytes should be postnatally replaced according to the extent of the loss.Indomethacin should be started in a low dose (0.2 mg/kg/day).Close monitoring of serum crea nine, urinary prostaglandin, and serum indomethacin levels is mandatory to detect drug toxicity and response to therapy.The dose of indomethacin can then be trated to achieve an adequate response.The indomethacin therapy has shown to decrease polyuria, renal saltwas ng, hyperprostaglandinuria, hypercalciuria, and nephrocalcinosis 10 .

Conclusion
Metabolic syndromes should be suspected in any child presen ng with vomi ng, polydypsia, polyurea, dehydra on and developmental delay.Audiological assessment should be done in all the cases of Bar er syndrome.Early interven on and mely audiological rehabilita on can improve quality of life in such children.