My Brother, 69 Had Been Started On Gabapentin 300mg. Which

My brother, 69 had been started on Gabapentin 300mg. which he'd taken for several weeks at bedtime for diabetes related peripheral neuropathy. His dose was increased to 600 mg. 2 evenings ago. The following morning, he awoke, tried to get out of bed and fell to the floor - his legs were very week, hands shakey, he had difficulty speaking, seemed confused, making odd requests, and was laughing inappropriately - he was able to walk but his legs were very weak - his wife decided to take him to the local ER however at the home door, both his legs gave out and he couldn't get up. She called the ambulance. He's been in the hospital - they stopped the Gabapentin immediately - he had CT scan - normal - all blood levels, electrolytes, urinalysis, all testing is normal. He's been gradually improving since admission, today is walking, talking normally, but memory problems remain. Docs beleive he had a reaction to the increase in Nuerontin.
Is this something your familiar with?