A practical approach to the late effects
It is not clear exactly what causes the late effects of polio.
There may even be several causes or a set of circumstances which
favours the development of new symptoms. Some recent scientific
concepts are explained below.
- Some think that the abnormal wear and tear
associated with residual polio explains the symptoms of
the late effects of polio. In other words, they do not consider this a
"new" condition but a logical consequence of the "old" symptoms.
Opponents to this concept have pointed out that even those who were
mildly affected by polio or who had no obvious residual effects can
experience its late effects (4).
- Others think that, due to the
diminished number of motor neurones after paralytic polio, signs
of ageing become more apparent in people who previously
had polio. An argument against this notion is that the late effects of
polio can start at any age and commonly well before the age of 60, when
the number of motor neurones starts to diminish in all of us (5). However, for
people past the age of 60, the combination of the two will need to be
taken into account.
- One of the early concerns was that the polio infection had
come back again; that the polio virus had become
reactivated. This reaction is understandable, since some
of the "new" symptoms resemble the "old" ones (such as pain, weakness
and respiratory distress). Tests have failed to detect the polio virus
in people who experience the late effects of polio and it is unlikely
that it can remain active in the nervous system for so long (6). There is
usually no need to worry about a new polio infection and the late
effects of polio are not contagious.
- There is some evidence that the immune
status is changed in people who previously had polio (7). An autopsy
study of spinal cords from people who had polio many years prior to
death showed signs of inflammation (8). This was an
unexpected finding. In another study inflammatory changes were also
found in fully recovered and originally spared muscles (9). Other
researchers have failed to confirm these findings of immunological and
inflammatory processes (7),
so there are still many question marks in this area.
- Some people with symptoms of the late effects of polio have
been, mistakenly, told by their doctor that they have the progressive
motor neurone disease, amyotrophic lateral sclerosis
(ALS). To receive such a diagnosis would be devastating, since ALS has
a rapid and fatal course. Luckily, there are several important
differences between these two conditions, the most important probably
being that the LEOP is relatively slow and mild, and, unless there are
important respiratory problems, it is certainly not life threatening.
The present scientific literature makes a clear distinction between
these two entities.
- The most common concept is
that the deficient post-polio neuromuscular complex is
prone to overuse because there are fewer nerve cells,
fewer active muscle fibres and deficient circulation in areas which
were affected by the polio virus (10). Excessive
use of post-polio muscles and nerves appears to precede their
deterioration. "Excessive" use is of course relative. Overuse is likely
to occur faster in deficient areas because muscles and nerves must work
harder to keep up with the requirements of daily living. Post-polio
muscles have also been shown to need longer time to recover from
activity than normal muscles.
Overuse fatigue is a common complaint and it can occur in all muscles;
those of the trunk (including the chest), the throat and mouth as well
as arms and legs.
© Copyright The Lincolnshire Post-Polio Network
1997 - 2010.
This document comprises an index,
introduction and sixteen other sections or subdocuments. Permission for
printing copies is granted only on the basis that ALL sections are
printed in their entirety and kept together as a single document.
Document preparation: Chris
Think-tank, Cornwall, United Kingdom.
Created: 30th December 1997
Last modification: 20th January 2010.