Phenytoin poisoning of the small blood vessels in the brain

Phenytoin was a medication prescribed by a GP and used twice daily by a close friend for severe cramps (toe to tongue) for more than 20 years without showing any known sign of detrimental effect, it is also used for epilepsy. The daily dose being taken was 200 mg in the morning, 300 mg at night making a total of 500 mg daily. Several times just lately the alarm bells were ringing by NHS professionals because this was apparently a huge dose, although six monthly blood tests by the GP were not showing any ill effect. It seems the picture was there, but not every piece of the jigsaw was in place.

Recently things were happening that could not be explained such as the patient dropping off to sleep every few seconds, with temporary memory loss, unstable gait and diplopia. The GP sent the patient to hospital fearing a stroke. A CT scan proved clear but the Phenytoin was stopped immediately as a result it seems of what they were able to see in the scan, poisoning of the small blood vessels in the brain, but how could this suddenly happen? The Phenytoin medication was replaced with Methocarbamol 750 mg four times daily for a one month trial. The cramps are subdued somewhat and still causing problems, but it is early days.

The purpose of this thread is not to run down the Phenytoin as a useful tool for severe cramps, because it has helped for more than 20 years; but rather to highlight how important it is to make sure you get blood tests on a regular basis if you are on this medication. I would suggest at least three monthly, rather than six monthly as was the case with the patient. However, that said a blood test was taken about fourteen days before the scan and it showed as okay, so how reliable are blood tests anyway?

A specialist neurological team are now wanting to find out what happened with the patient so this thread will continue, although updates I suspect will be few.

Are you taking Phenytoin for severe cramps and if so what are your thoughts?

The Phenytoin was stopped completely (500 mg daily to nothing!) and replaced with Methocarbamol 750 mg four times daily, but side effects quickly appeared such as feeling sick soon after taking the tablet, 'internal' tremors, pins and needles in the feet with the feet feeling cold also, yet they are not. Joint pains are also increased.

The cramps persist, mainly an early morning thing 04:30 to 06:30 but the residual cramp pain suggests that the Methocarbamol isn't having the desired effect.

NHS professionals have reduced the 750 mg four times daily to 750 mg three times daily for two weeks and suggest it be reduced again thereafter.

The patient dropping off to sleep every few seconds previously, with temporary memory loss, unstable gait and diplopia appears to have ceased. That at least is progress, but at what cost, what has the Phenytoin poisoning done that can't be seen thus far?

The Methocarbamol was stopped and the side effect 'internal' tremors continued for two days after and then ceased completely. The feet are back to normal with the 'cold but not cold' side effects no longer a problem. (The brain was saying the feet are cold, but the feet were in fact warm to the touch).

The Pain Clinic has prescribed Quinine Sulphate 200 mg to be taken at night for cramps, which appears to be very effective at this stage.The irony is that it was Quinine Sulphate 200 mg that was stopped more than 20 years ago, to be replaced by Phenytoin.

Aching joints are still a problem, but it could be osteoarthritis which the patient suffers or bursitis, and controlled to some extent with Voltarol, Paracetomol, MST and Oramorph for a quick fix when necessary.

An improvement....maybe?