tchair

I am not an expert nor trained in medicine, and my experiences are anecdotal. I've been on Dilantin for over two years for nerve damage pain. I experienced similar symptoms which were dose/blood level related. We worked up to 800 mg per day and down. My symptoms correlate closely to dose and we found no more than 400mg tolerable Here is what I have exprienced: 450 mg feet numb, hands won't grip, 500 mg peripheral vision and depth perseption poor, lower lip flops, 500+ pants get damp, occasionally very difficult to sit upright. This is my individual weight, metabolism, etc. Symptoms have come on without change in dose (But possibly blood level variation. They usually do testing after I've had problems.)
Side effects seem to do with limited nerve signals, basically how Dilantin works. My understanding is that liver function tests are recommended to the doctors for both it's efficiency in metabolizing Dilantin, and reduced function due to the drug. I now recognize these early indicators for me; gums feeling more swollen than usual, missjudging distances, and things dropping out of my hands. On occasion a precursor has been comments from others of a guant appearence in my face.
My worst experience, when I could barely walk unaided, tested out at a level of 40mcg/ml, days after I had stopped taking it due to the side effects. On each occasion that I stopped,the symptoms got WORSE before they got better. For me, slowly reducing the dose resulted in the most severe problems. To me this seems to be a reciprocal reaction from the nerves being deprived of the medication.
These problems were greatly reduced since my nuerologist switched me from four 100mg capsules to eight 50mg chewables per day.
A word of warning. Very few professionals have demonstrated any familiarity with this drug and its effects. My dentist that I've known for 25 years instantly became 'seizure' paranoid until I explained the reason for the prescription. My GP literally ignored my symptoms and diagnosed depression. Fortunately his lab nurse educated him as to the test results and their ramifications. A semi-appology followed with the order to go see whoever gave it to me.
If you get a data sheet from your pharmacy you will see; 'sensory peripheral polyneuropathy observed .... in some long term phenytoin (Dilantin) therapy'.
I have two 'suggestions'. One is to get the proper tests. The other is that any change in dose, up or down might actually be agrivating the symptoms.