- Residual Effects Following Guillain-Barré
-
Gareth J. Parry
Consultant Neurologist, Auckland Hospital
Professor of Neurology, University of Minnesota
Published in "The
Communicator" Spring 2003
Guillain-Barré syndrome is a disorder whose
excellent prognosis is invariably emphasized. Widely accepted figures
suggest that 75%-85% of patients make a complete recovery. However,
many of my patients have complained to me of minor but annoying persistent
symptoms continuing for years after the initial paralytic event. Although
I have made no systematic study of the proportion of patients with
these residual complaints it is certainly more than the 15%-25% that
the figures in the literature would suggest.
The great majority of studies of GBS outcome are based
on telephone interviews or retrospective chart reviews and seemingly
minor complaints may have been missed or disregarded. Thus, patients
are often asked if they have returned to their previous work or other
previous activities but they may not have been asked whether they
have more difficulty performing their former activities.
A note of caution was sounded in one small study from
Dr. J. McLeod and his colleagues in Australia who objectively evaluated
a small group of 18 recovered GBS patients and found that half of
them had residual neurological abnormalities. Even then the residual
abnormalities were considered to be significant in only four patients.
A recent important paper from Dr. I.S.J. Merkies and
colleagues in Holland (Neurology 1999; 53:1648-1654) has established
that residual effects from both GBS and CIDP are much more common
than has been generally reported and that seemingly minor neurologic
abnormalities may still result in annoying disabilities.
The study used a validated index of fatigue severity to assess residual
disability. It included 83 patients who had suffered from GBS an average
of five years previously. About 80% of these patients experienced
fatigue that was considered severe enough to interfere with their
life despite that fact that the majority had normal strength or only
minor weakness.
They noted also that the fatigue did not seem to improve over time;
the fatigue index score was the same in patients in whom many years
had elapsed as it was in patients whose acute illness had occurred
only 6-12 months previously.
This paper provides sound scientific support for the
validity of the observations of my patients who regularly complain
of fatigue even when they have returned to all or most of their former
activities and who are working full time at their former jobs. Although
their strength may be normal when they are examined in the doctor's
office they are clearly unable to sustain the same level of physical
activity that they had performed prior to their GBS.
A second under-appreciated symptom that may persist
for many years is pain. Certainly, severe disabling pain is very rare.
However, a number of my patients complain of persistent discomfort
in their feet. The discomfort may take the form of annoying paresthesias
(tingling) or there may be a vague aching discomfort. The symptoms
have the same characteristics as typical neuropathic pain in that
they tend to be worse in the evening or at night and are particularly
annoying following days during which the patients have been up on
their feet a lot.
The discomfort is not particularly responsive to analgesics but usually
does respond to drugs such as gabapentin or amitriptyline, drugs typically
used in the treatment of neuropathic pain. However, these medications
have to be taken on a daily basis to be effective and one problem
with deciding whether to treat this residual symptom is that the discomfort
is usually rather mild. Thus, patients may be daily irritated by their
symptom but be reluctant to take a drug every day for a symptom that
significantly bothers them only once or twice a month.
I have seen no mention in the medical literature of
this phenomenon. It is possible that I see a highly selected group
of patients in my practice who had initially been more severely affected
and that the prevalence of this annoying residual symptom is much
higher in my patients than in the usual population of recovered GBS
patients. I would be most interested to learn whether the group of
patients reported by Merkies and colleagues also suffered from minor
persistent discomfort.
The basis for both of these seemingly minor residual
symptoms (fatigue and pain) is probably axonal degeneration. During
the acute illness the predominant underlying pathology in most patients
is segmental demyelination, a completely reversible phenomenon. However,
some degree of axonal degeneration is almost invariable. As recovery
occurs function is restored by a number of mechanisms.
Axonal regeneration of motor axons probably plays very little role
in restoration of function except in the more severe cases. Rather,
surviving axons send out small branches called collateral sprouts
that restore the nerve supply to those muscle fibers whose nerves
have been damaged. This process of collateral sprouting is very effective
at restoring strength to a muscle but the efficiency of the muscle
suffers - the muscle must work harder to achieve its goals. Thus,
fatigue may result even when there appears to be full restoration
of strength.
On the sensory side, even a small number of damaged sensory axons
may be sufficient to generate spontaneous discharges that are registered
as pain or discomfort.
It is entirely appropriate that the good outcome of
GBS should be emphasized during the acute illness. During this time,
the patient is losing control of many motor functions, sometimes including
life preserving functions, and constant reassurance from the attending
physicians plays a vital role in the recovery process.
However, it is equally important to be aware that residual problems
are experienced by "recovered" GBS patients. Acknowledgement
that such residual problems exist will go a long way towards helping
patients deal with the frustration of their incomplete recovery.
More research is needed to discover an effective treatment
for the residual fatigue. In addition, since these persistent symptoms
are probably related to the degree of axonal damage that occurs at
the time of the initial attack, we also need to continue to strive
for earlier and more effective treatment of the acute stage of the
disease so that these residual problems are minimized.
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