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Tuesday, March 4, 2014

A Disorder I've Never Seen


“I’ve been trying to pick up stuff, and I can’t,” said a Ramada guest. “It started a half hour ago.”

“You mean your arm is weak?” I asked.

“No. Once I grab it, it’s OK.”

“Is it numb?”

“It feels fine. But when I reach out for something, I miss it. It’s weird.”

The guest was elderly but in good health. I suspected I knew the problem.

“Take your forefinger and touch your nose,” I suggested. “Can you do it?”

“No,” he said. “I keep hitting my face.”

This was something I’d never encountered but luckily I remembered my medical school neurology. This lady had suffered a cutoff of blood to her cerebellum, a structure at the base of the brain that controls coordination.

When you reach out, the brain instructs muscles to move your arm in the general direction of your goal. That’s the best it can do. The last few inches don’t require strength or mobility but fine, precise movements. That’s where the cerebellum takes over.

With the cerebellum out of action, you’d have normal consciousness, strength, and sensation but no coordination. You could walk but only slowly with a clumsy, wide-based gait. If you reached for something, your hand would wobble wildly as it approached. The classic test is to ask a patient to put a finger on her nose. Without a cerebellum, it’s almost impossible.

It could have been a temporary loss of blood supply, a “transient ischemic attack” (TIA) or a permanent loss, a stroke. Waiting to see which would be unwise, so I urged her to go to a hospital where she was admitted.

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