EMG and Previous Polio
Question: I have a friend, in her 70’s who is now developing weakness in her hips. She was around me when I got polio and her cousin was the carrier. The question is can she have a normal EMG and still have had polio? The doctor told her that she could not have had polio because she had a “normal” EMG.
Dr. Bruno’s Response: Studies have shown that 10% to 25% of polio survivors have normal EMGs because their nerves were damaged but not killed. As a result, there are no neuron “sprouts” to show up on EMG. In one study, almost 10% of patients who had a history of polio muscle weakness, and who were reporting new pain, fatigue or weakness today, had normal EMGs, meaning that there was no EMG evidence that they ever had had polio. Another EMG study found that almost 25% of paralytic polio survivors' limbs had no evidence of motor neurons having been killed. Those limbs were classified as having "no clinical polio". However, neurologist Carlos Luciano, using a special "macro" EMG technique, found over-sprouted motor neurons in 85% of muscles that were thought to have had "no clinical polio." This is not surprising since research by David Bodian and Alan McComas showed that seemingly unaffected muscles had lost 40% of their motor neurons to polio.
As for being around you when you had polio and her cousin being the carrier, in 5% to 20% of households where poliovirus attacked one family member, another was also stricken. From 1909 to 1955 more than 2000 family members in more than 1000 households were surveyed in which at least one person had polio. On average if one child in a household became ill he "shared" polio with one other sibling of similar age. Just over half of those who became ill were paralyzed, while the others had flu-like symptoms ranging from a fever, sore throat and nausea to a stiff neck and muscle pain. This "minor illness" was caused by the poliovirus but may never have been diagnosed as polio at all, or may have been called "abortive" or "non-paralytic" polio. In three-quarters of the households the first case of polio was paralytic and the second was "non-paralytic."
Bottom line: There's about a 1-in-5 chance that if you had paralytic polio one of your brothers or sisters had non-paralytic polio and may not even have known it.
There is more information on “EMG” and “Non-Paralytic Polio” listed in the Index for the Encyclopedia of Polio and PPS.