Uncontrollable hand shaking may be focal seizure

Dear Dr. Roach: My right hand started shaking uncontrollably one day recently. It did not stop for two hours. Earlier this year, I found that it shook whenever I tried to write, and I had to use a note-taker. My left hand has had issues for years, shaking mostly when reading the paper or holding something. I am 66 and have a number of underlying conditions, including two types of epilepsy. I have not taken anything for epilepsy in several years; I just try to avoid all triggers. Could this be the focal form manifesting itself? — S.G.

Answer: Seizures have been categorized in different and confusing ways, but currently, seizures are described as generalized — that is, affecting both sides of the brain, versus focal, which is on one side. Sometimes people with epilepsy can have both focal and generalized seizures.

Generalized seizures can have motor symptoms (the most familiar are the tonic-clonic seizures, formerly called “grand mal”) or non-motor symptoms (such as the absence seizure, formerly called “petit mal”). Seizures may affect consciousness, or people can retain consciousness during seizures.

What you are describing sounds to me like a focal seizure without any impairment of consciousness. This also goes by the name of epilepsia partialis continua. This often happens in people with a history of focal epilepsy, especially in times of stress. The first time I saw this was in a gentleman who had high blood sugar from unrecognized diabetes.

Dear Dr. Roach: The herbicide glyphosate has been cited as a possible cause of cancer. Is the greatest risk from using the product at home and in farming applications, or from eating agriculture products that are resistant to glyphosate when used for weed control? — A.R.

Answer: I often read that glyphosate has been linked to cancer, but when I researched the connection, I found several well-done trials that show there is no strong link to cancer. (I say “strong link” because it is impossible to prove that there is no link.) For example, in people whom we would presume to have a high exposure — the workers who apply the pesticide — a well-done study by the University of Washington and the National Institutes of Health showed no significant increased risk for cancer overall, or for any of the 13 different subtypes of cancer they evaluated.

The available evidence suggests that glyphosate is relatively nontoxic and is unlikely to be cancer-causing even if consumed in high amounts. However, I still recommend thorough washing of produce to remove residual pesticides (even organic produce still may have pesticides).

Email questions to toyourgoodhealth@med.cornell.edu.