Disability in the News.
Drug Helps Spinal Cord Injury Patients.
TORONTO, Sep 28 (Reuters) -- Encouraging results have been observed following a 3-month trial of the drug 4-aminopyridine, a potassium channel blocker, in patients with long-standing spinal cord injury.
It is among the few beneficial effects of drug therapy in long-standing spinal cord injured patients reported, Dr. Jack Segal of the Veteran's Affairs Medical Center, Long Beach, California, said at the joint meeting of the American College of Clinical Pharmacology, the Canadian Society of Clinical Pharmacology, and the Royal College of Physicians and Surgeons of Canada.
Segal reported that on average, patients regained at least 1 to 1.5 neurological levels of function after 3 months of treatment with 30 milligram per day doses of 4-aminopyridine. Control patients on low-doses (6 mg/day) of the drug showed no significant improvement in any of the primary or secondary outcomes over the same study period, he added.
Following injury to the spinal cord, many of the nerves at the site of the injury lose their protective, myelin sheath. This interferes with the conduction of nerve impulses across the damaged areas. The drug 4-aminopyridine is thought to be capable of helping impulses cross demylinated nerves, thus restoring some function.
The study involved 21 patients, all with spinal cord injuries of at least 2 or more years duration. Of these, 14 were quadriplegic, with paralysis affecting all four limbs, and seven were paraplegic, with paralysis affecting the lower limbs.
Sixteen patients received full-dose (30 mg/day) 4-aminopyridine, while six patients received 6 mg/day 4-aminopyridine and served as controls. The investigators looked at the patients' composite motor scores as well as tests of sensation. Both measures increased significantly after 3 months in the 30 mg/day group relative to baseline.
``This improvement translated not only into scores that we could quantitate, but there were significant changes in patients' ability to carry out activities of daily living,'' Segal said. For example, some patients became able to independently transfer from wheelchair to bed. Others reported enhanced sexual function and some patients recovered bowel and bladder function, Segal noted.
A significant improvement was also seen in spasticity, increased muscle tone and uncontrolled spasms, which is a common problem in spinal cord-injured patients. Spasticity frequently manifests as painful muscle spasm, especially at night. ``As a result, some patients who hadn't had a full night's sleep for years reported significant improvement in sleep,'' Segal said.
Equally, if not more importantly, he said, 4-aminopyridine improved pulmonary function by 30% to 40%. Since pulmonary infections are a frequent cause of morbidity and death in the spinal cord patient, the ability of 4-aminopyridine to strengthen respiratory muscles and the diaphragm, and to improve the patient's ability to breathe, cough and clear secretions could directly translate into a reduced susceptibility to pulmonary infections, Segal said.
He warned that 4-aminopyridine is contraindicated in acute spinal cord injury because it carries an increased risk of seizure in the acute injury setting. However, Segal said that the drug can be considered in patients whose injuries are a year or more in duration. Taken with meals, the drug is also reasonably well tolerated, he added, with no serious adverse events observed in the study group of patients over the 3-month trial.
Segal also noted that longer-term treatment with 4-aminopyridine, which many of the patients in this initial study have remained on, may continue to enhance sensory and motor function. In his experience, patients who continue with treatment go through interludes where they suddenly gain additional, noticeable improvement in function, which are followed by plateaus. This phenomenon suggests that patients with long-standing spinal cord injuries may continue to improve with longerterm use of 4-aminopyridine, he commented.
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