Looking in my drafts folder, I found this post, which I believe I may have posted elsewhere. Six years ago… doesn’t time fly. Amended a broken link, but I thought it was time for this to be posted here. I suppose ‘crush’ in HNPP terms can actually be rather minor pressure, but I think it is a fairly common presentation in HNPP. So without further… Here it is… zombie post no more…
Generally speaking the consensus among medical professionals is that Double crush injuries, ie two (or more) nerve entrapments along the same peripheral nerve bundle is relatively rare. It has been suggested that some refractory (those not responding to treatment) carpal tunnel injuries may be due to another peripheral nerve entrapament/lesion at a proximal (closer to the spine) location, such as the shoulder or neck.
There is some controversy surrounding this syndrome and some believe that it doesn’t exist. In terms of treatment and the success or failure of it for carpal tunnel in the absence of any other nerve pathology, it may indeed be debatable. But what about the cases where other nerve pathology exist, for example another peripheral neuropathy.
Having been diagnosed with HNPP (Hereditary Neuropathy with liability to Pressure Palsy) it has become fairly obvious to me that such a problem of multiple nerve compressions do exist. With HNPP these compression could be momentary and of fairly short duration but will cause prolonged entrapment-like symptoms. I would have thought that double crush syndrome would be far more common in HNPP than in the general population, simply due to the increased liability.
Part of of the postulation for Double Crush, is that the distal compression, eg Ulnar nerve entrapped at the elbow, appears to be far worse for the contributary factors due to a proximal compression of the same nerve branch, for example a compression at the axilla or the neck at vertebrae C8 and or T1. (Diagram of Brachial plexus and nerve division)
The upper nerve compression (proximal) is likely to have much wider effects than the lower compression (distal), but is it possible that the lower compression can appear much worse due to rather trivial compression at the higher (more proximal) location. It has been my experience that this does indeed happen in HNPP, and can cause sudden worsening of a lower palsy, i.e. an area of sensation loss with varying degrees of muscle weakness.
Another example from my own experience is that of foot drop and lower leg neuropathic pain, which can worsen considerably when I have problems of the lower back, with sciatica in attendance. Any neuropathic pain seems to be amplified at the distal location during these times as does any sensation loss and muscular weakness.
Perhaps this is more likely to happen as the person with HNPP ages, as the multiple locations of previous palsies begins to take it’s toll. It can make this highly variable condition even more unpredictable and difficult to manage.