I had a clue what this might be when Autumn asked me “can we squeeze in Sally Smith for leg numbness and a groin rash”, although I didn’t know the extent of the numbness or the specifics of the rash.
So we double booked her and I listened to her story. The numbness was only in the front of her left thigh and started somewhere around the groin. Her strength was normal and the sensation below the knee was perfectly normal. When I touched the numb area she told me it hurt, so it wasn’t just numb, it was numb and painful at the same time. Looking at the rash, it was a cluster of blisters in her left groin about the size of my fist and she also had a small patch of smaller blisters around the corner in the upper left gluteal area.
Sally had had a couple of outbreaks of painful blisters before. A couple of years ago I gave her valacyclovir for what looked like herpes simplex in her face. She became violently ill on a modest dose. She is also intolerant of gabapentin, which she had tried for sciatica in the past. She has a history of chronic back pain.
She has had the shingles vaccine, both doses of the newer one, so supposedly shingles isn’t likely to happen to her but it was clear to me that her numbness with pain qualifies her for the diagnosis of meralgia paresthetica.
This condition is usually caused by pinching of the lateral cutaneous femoral nerve as it exits the pelvis in the groin. People with large bellies are more likely to get this. Sally is a slender woman. But she was too tender and sensitive for me to feel for a hernia or lymph nodes in the groin. Even the slightest touch was unbearable for her.
So in this case I think her meralgia paresthetica isn’t caused by a big belly. Rather, I suspect the virus itself and possibly any associated swelling of lymph nodes or other soft tissues are the culprit.
So I reassured her I thought this would go away by itself. But, in the meantime, what could I do?
She is already on hydrocodone for her chronic back pain. And she confirmed when I said hydrocodone doesn’t usually do much for nerve pain. Lyrica would be too similar to gabapentin to try and duloxetine would probably take too long to help her. So I offered her low-dose amitriptyline and a burst of prednisone.
She will call me in a couple of days to report how she is doing and she already has a routine visit in a week and a half.
If she is agreeable, I would suggest a trial of acyclovir. I know valacyclovir is of course a prodrug of acyclovir, but I have a patient who has taken acyclovir bid for HSV suppression successfully for 30 years – switching to valacyclovir once a day produced a dramatic recurrence of frequent outbreaks. So for some reason they are not “always” the same drug in a given person’s body