You're right that a lot of the studies on Piracetam and seizures have been small, and no significant studies done in the US (my epileptologist says it's because it's so cheap, the drug companies won't fund a study because there's little potential profit). But it does show some promise especially for infants with myoclonus (used as first line treatment for that in Europe), and also as an enhancer for AEDs without significant side effects.
A use of high dosages of piracetam in the treatment of Kozhevnikov epilepsy syndrome
http://www.ncbi.nlm.nih.gov/pubmed/18379510
Russian study, 2007, on Rasmussen disease. 6 child patients (9 to 16 years) who received 1 g per kilo body weight Piracetam per day (intravenous) up to 35 g/day. Treatment for 30 days.
Results:
3 became free of myoclonic seizures; other 3 received 75% improvement.
2 became free of focal clonic seizures; other 4 decreased in frequency
2 became free of secondary generalized seizures; other 4 had 50% or greater improvement
Neurological improvement in 5 out of 6
Hemiparesis intensity reduced in half of children.
Cognitive functioning enhanced in 5 out of 6
Long-term efficacy and safety of piracetam in the treatment of progressive myoclonus epilepsy.
http://www.ncbi.nlm.nih.gov/pubmed/11346373
http://archneur.jamanetwork.com/article.aspx?articleid=779361
Canadian study, 2001. 11 (age 17-36) patients w/ progressive myoclonus. Initial dose 3.2 g/day, titrated up to 20 g/day. 12 month study. Significant overall improvement. 2 patients received dramatic decrease in tonic/clonic seizures. Side effects: 2 patients reported drowsiness in first 2 weeks of treatment. 1/3 of patients experienced gastrointestinal discomfort, but no diarrhea, and effect was temporary. Best effect when given as an adjunct with Valproic Acid or Clonazapam.
Piracetam in the treatment of cortical myoclonus
http://www.ncbi.nlm.nih.gov/pubmed/10338109
French study, 1999. 12 patients, double-blind w/ placebo. 7 year study. Dosage 7 to 48 g daily. Tolerability on long-term, high dose quite good. No serious adverse effects. “Marked and sometimes spectacular improvement” that continued for up to 7 years. Researchers recommend the daily dosage be increased until improvement seen (since tolerability is high). They also recommend usage as adjunct or monotherapy, and as first line treatment for cortical myoclonus.
Piracetam relieves symptoms in progressive myoclonus epilepsy: a multicentre, randomised, double blind, crossover study comparing the efficacy and safety of three dosages of oral piracetam with placebo.
http://www.ncbi.nlm.nih.gov/pubmed/9527146
Finland study, 1998. 20 adult patients. Doses ranged from 9.6 to 24 g/day. Study measured improvement in functional disability caused by myoclonus epilepsy, and found improvement in motor skills and other assessments. Improvement significantly related to higher doses, although significant improvement seen even at lower dose. Side effects mild and transient.
Clinical use of piracetam in epileptic patients
http://www.sciencedirect.com/science/article/pii/S0011393X05804072
Pakistan & Belgium, 1992. 60 patients with epilepsy (adult & child), double blind. 15 age matched control subjects. Prior to study and at conclusion, each subject tested for memory, intelligence scale, EEG, and neurologic exam. Piracetam enhanced cognitive scores for patients with epilepsy, did not interfere with AEDs, and enhanced performance of some AEDs.