Our study suggests a strong trend for the conversion of stone disease from calcium oxalate to calcium phosphate containing stones, which could influence the progression and severity of disease.

We report the occurrence of felbamate stones in a series of patients on high dose felbamate therapy. Accurate diagnosis is made more difficult by the clinical complexity of the patient population (including severe developmental delay), the radiolucent nature of the stones and the possibility of inaccurate analysis of stone composition.