"What we're really hoping is, a lot more studies will come from this," Barbara Koppel, chief of neurology at New York Medical College and one of the review authors, said at a news conference. The journal Neurology will publish the study Tuesday.
"There's a place for it," she said of medical marijuana, "and more work will need to be done to find out where its indications will be."
Medical marijuana is legal in New Jersey, 19 other states, and the District of Columbia, but not in Pennsylvania. On Monday in Harrisburg, parents who want to use medical marijuana for their children's seizures threatened a sit-in until Gov. Corbett agrees to meet with them.
The review team examined 32 studies in which pill and oral spray forms of marijuana were used, as well as the smoked version. Two pills are approved by the Food and Drug Administration to treat nausea. They can be prescribed in any state.
Ken Wolski, a nurse who is executive director of the Coalition for Medical Marijuana New Jersey, said there was a "tremendous amount" of anecdotal evidence that marijuana helps people with neurological conditions. Extensive clinical trials are very hard to do, he said.
Epilepsy patients have been among vocal supporters of medical marijuana, but so have those with other neurological conditions, Wolski said. He has heard from epilepsy patients who said they got better with marijuana after antiseizure drugs and surgery failed.
Allison McCartin, executive director of the Epilepsy Foundation Eastern Pennsylvania, agrees that "there isn't a lot of data" but said her members want the opportunity to try medical marijuana when all else has failed.
"We've got kids that struggle with hundreds of seizures a day," she said. "We can't wait for these studies to come out."
The neurologists pointed out that marijuana can have serious side effects, including nausea, fatigue, suicidal thoughts, dizziness, and intoxication.
The study found that the pills and oral spray could help spasticity, pain, and overactive bladder. There wasn't enough evidence for smoked marijuana.
Pills did not help Parkinson's patients suffering from side effects of levodopa, the main drug used to treat the disease.
The reviewers found insufficient evidence to say that marijuana in any form helped with the movement symptoms in Huntington's disease, tics in Tourette syndrome, cervical dystonia, or seizures in epilepsy.
Clyde Markowitz, a neurologist who runs the University of Pennsylvania's multiple sclerosis program, said he still has reservations about the side effects and long term consequences of medical marijuana. "I think it's something that needs to be studied before we can make recommendations on a large scale," he said.
Mark Angelo, a palliative care specialist at Cooper University Hospital, is more comfortable with medical marijuana. He is among 286 doctors in New Jersey who may certify that patients qualify for marijuana. Among the neurological conditions sometimes covered are multiple sclerosis, epilepsy, and muscular spasticity.
New Jersey patients can get marijuana plant material, buds, or an oil at one of three Alternative Treatment Centers.
Angelo's patients use medical marijuana to augment pain drugs, stimulate appetite, and reduce nausea and vomiting. "The patients who've used it have been very, very happy," he said.
In New Jersey, 2,000 people have registered to use medical marijuana and 1,733 have been served since the first center opened on Dec. 6, 2012, according to the New Jersey Department of Health. About 222 pounds of marijuana had been dispensed to patients and caregivers by April 22.