Successful treatment with topiramate in a case of idiopathic intracranial hypertension refractory to acetazolamide

: A 6-year-old girl experienced nausea and vomiting for 3 weeks and double vision for 1 week prior to her first visit to our hospital. She had bilateral ophthalmoplegia from sixth cranial nerve palsy and papilledema. Her brain MRI showed normal brain parenchyma. The lumbar cerebrospinal fluid (CSF) opening pressure was 1000 mm of water measured with normal CSF contents. From these findings, she was diagnosed with idiopathic intracranial hypertension (IIH). Initial lumbar puncture (LP) immediately improved her symptoms, but acetazolamide, a first line drug for the treatment of IIH, failed to maintain the remission, and three more periodical LP were required to relieve her symptoms every 2 weeks. After the fourth LP, acetazolamide was switched to a second line drug for IIH, topiramate, which was found to be highly effective in controlling IIH in a short time period. The long process of IIH causes vision loss, therefore, its prompt treatment is vital. In cases refractory to medical treatment, surgical treatments such as CSF shunt are considered. Acetazolamide is used in most IIH cases after the initial diagnosis, but in this case, it was ineffective, and topiramate was highly effective. Both acetazolamide and topiramate are inhibitors of carbonic anhydrase isoforms involved in CSF secretion. Inhibition of choroid plexus carbonic anhydrase by these drugs leads to decreased CSF secretion and the consequent control of intracranial pressure. Higher isoform specificity and increased lipophilic nature of topiramate, which are advantageous for passing through the blood brain barrier, may be the reasons for better activity than acetazolamide, at least in the present case. Topiramate might be effective and should be considered for refractory IIH cases before surgical treatments.