My 77-year-old father is in pretty good shape all things considered. But he’s had terrible back and leg pain and leg cramps for months now from spinal stenosis. He agreed to have surgery to take pressure off the nerves but it didn’t seem to help him. He can walk a little further but he still says his pain is pretty debilitating. And he still has leg cramps at night. Why didn’t he get better?

Painful leg cramps during the day or at night can be very disturbing — both to daily activities and to sleep. And many aging adults complain of this problem, so it has caught the interest of doctors and scientists around the world.

So far, scientists still don’t know exactly what causes leg cramps to start. In the case of spinal stenosis, pressure on the spinal nerves leads to pain, especially when standing upright and/or walking. Stenosis is a narrowing of the spinal canal around the spinal cord. This type of narrowing can also affect the foraminal spaces (holes) where the spinal nerves pass through the vertebral bone in order to travel down to the legs.

But a recent study from Japan also showed that decompressive surgery such as your father had doesn’t really give the kind of pain relief doctors and patients expect. They have identified various other health conditions that may be linked with leg cramps but still don’t know the mechanism that leads to this symptom.

It may be a problem at the motor unit of the muscle. Once the nerves were unimpaired, the motor units fired up too much, causing hyperexcitability. This hyperexcitability of the motor units then resulted in leg cramps.

It’s possible the lumbar nerve roots affected were damaged beyond repair. Removing the pressure from around them was too little too late. And possibly, since many surgical patients can walk farther after surgery but still have pain, perhaps muscle fatigue and a build-up of cell byproducts in the legs leads to leg cramps.

It’s clear that leg cramps disturbs peoples’ quality of life. Further study is needed to really get down to the bottom of leg cramps. Besides finding out what causes this problem, there’s a need to find treatment that works well. Decompressive surgery may help some walk further but doesn’t really improve the symptoms for all patients.