By DONALD G. McNEIL Jr.

After her stroke, Francine V.Corso, a software engineer who worked on NASA’s lunar lander, was housebound from 1992 to 2001.

Her left arm was twisted up near her neck, making it difficult to pull on a blouse, and her fingers curled so rigidly that her nails buried themselves in her palm. When she finally learned to rise from her wheelchair, her contorted left leg had the so-called horse gait of many brain-injury victims - she stepped toedownward, and then fought to keep her foot from rolling over.

Now, with injections of botulinum toxin every three months, she says,“I’m completely transformed - I drive, I volunteer, I take art classes.”Her fingers are so relaxed that a manicurist can paint her nails red.

Botulinum toxin, the wrinkle smoother best known by the brand name Botox, has many medical uses. It helps dystonia victims regain control of spasming muscles, actors who struggle with excessive sweating and children with clubfoot avoid surgery.

Its use in stroke victims is still off label - that is, it is not approved for that purpose by the Food and Drug Administration. But it is so widely accepted that the federal Medicare program and other, private insurers will usually reimburse for its use.

Nonetheless, said Dr.David M.Simpson, a professor of neurology at Mount Sinai Medical Center in New York and a leading botulinum researcher, only about 5 percent of the stroke patients who could benefit from its use ever get it.

Relatively few doctors are trained to do the injections, which go much deeper than dermatologists do to erase frown lines. And most neurologists are in the habit of prescribing antispasticity drugs like tizanidine and baclofen, which are oral and inexpensive, but which cause drowsiness and weaken every muscle in the body, not just the target ones.

Ms.Corso, 66, never heard about the treatment from her first neurologist, whom she called“Dr.Bad News”because he told her family she would die and then kept telling her she would never walk.

In a Mount Sinai classroom, with a broad view over Manhattan, Dr.Simpson stands behind two disembodied arms mounted on rocker joints. One looks pasty but muscular and is covered with needle tracks. Its partner is bright red and nothing but muscle; it is an anatomical model with all the skin and fat removed.

Dr.Simpson, who gets financing from three botulinum toxin producers, is teaching residents how to find the harder-to-reach muscles, like the flexor pollicus brevis, which bends the thumb, and the pronator quadratus, which rotates the wrist.

The rubber arms have sensors that beep when the tip of his needle enters the right muscle. Human arms do not beep, of course, but Dr. Simpson had used a variant of the technology on Ms.Corso only an hour before.

Just before the first needle sank in, she let visitors know how she felt about electromyography, which she calls“the stim.”

“This,”announced Ms.Corso, who is almost 1.5 meters tall,“is what separates the men from the boys.”

The syringe was wired to an electric stimulator that pulsed a charge - up to a tenth of an amp - twice a second. When Dr.Simpson believed he had pierced the right muscle, he increased the charge. If the correct finger began twitching in sync, he knew he was there, and pressed the plunger. If not, he moved the needle and tried again.

He did that several times in Ms.Corso’s arm and then in her leg. Within 45 minutes, Ms.Corso said her foot was hitting the floor more evenly.

Dr.Mark Hallett, chief of the motor control section of the National Institute of Neurological Disorders and Stroke, says he uses both electromyography and ultrasound when injecting patients.

“A number of authorities feel that if they get close, that’s good enough,”Dr.Hallett said.“I don’t agree. I think it’s valuable to make sure you’re in the right place.”





Francine V.Corso, a stroke patient, with Dr.David M.Simpson, said Botox allowed her to regain mobility. Sensors on a rubber arm help medical students learn how to administer the treatment.