Looking on helplessly while a wave of weakness climbs one's body from the ankles upward can cause dismay. This is what happens in Guillain Barre (pronounced GHEE-on bah-RAY) syndrome, known more formally as acute inflammatory demyelinating polyradiculoneuropathy. Occurring in just one or two people per year in a population of 100,000, Guillain Barre syndrome makes up for its rarity by taking people by surprise and quickly disabling them. Acute inflammatory demyelinating polyradiculoneuropathy is about as bulky and awkward a name as there is, but the terminology has the endearing feature of encoding the disease's essential features. Starting from the back end and working forwards, "-pathy" means illness; "neuro" says that the peripheral nerves are involved; "radiculo" means that the spinal nerves emanating from the spinal cord are also affected; "poly" means it's a widespread process; "demyelinating" means that the nerve-fibers are stripped of their sheath-like myelin coverings; "inflammatory" means a local tissue reaction to biochemical or physical irritation; and "acute" means that the disease develops rapidly over a matter of days. Despite the lesson in medical terminology provided by the full name, it's easy to see why the condition often goes by the shorter names of AIDP or Guillain Barre Syndrome (GBS). Georges Guillain and Jean-Alexandre Barre described cases of this condition among French soldiers in the First World War. It is noteworthy that the condition is labeled a "syndrome," rather than a disease, because it is likely that multiple disease-processes can produce the same pattern of clinical illness (syndrome). Diagnosing GBS involves recognizing the typical pattern of progressing symptoms in which a loss of strength works its way up the legs and often even into the arms and breathing muscles. The symptoms quickly worsen over a matter of days, even hours, and the weakness typically peaks within 2-3 weeks of the onset of symptoms. Although the affected peripheral nerves and spinal nerves also conduct messages concerning bodily sensation, sensory loss in GBS is typically a minor component, while weakness -- caused by disruption of nerves carrying messages to muscles -- predominates. The physical exam confirms the muscular weakness and, when present, the associated numbness. Another classic finding on examination is a loss of (rubber-hammer-type) tendon reflexes. Supplemental tests that help confirm the diagnosis -- or, depending on their outcome, point in another direction -- are nerve conduction studies and cerebrospinal fluid analysis. Nerve conduction studies check the electrical characteristics of the peripheral nerves. In GBS the nerve impulses are often slowed or blocked on their way from one part of the nerve to another. Cerebrospinal fluid is the watery liquid bathing the outside of the brain, spinal cord and spinal nerves. It is obtained for analysis by means of a lumbar puncture, also known as spinal tap. In GBS the protein content of the fluid is increased without any corresponding increase in the numbers of red or white blood cells in the fluid. The cause of GBS is unknown, but because it often follows an infection or other challenge to the body's immune system and also involves inflammation, it seems likely that GBS is the result of an overactive immune system. If so, GBS is one of several so-called autoimmune diseases in which the body's own immune system mistakenly attacks a component of the body, in this case the myelin coverings of individual nerve-fibers. Other examples of autoimmune disease are rheumatoid arthritis, in which the immune system attacks the joints, and psoriasis, in which the immune system attacks the skin. A case series refers to a collection of consecutive cases sharing agreed-upon features. Analyzing a case series provides insight into how variable the illness can be as well as which features are more constant. Between 1995 and 2003 researchers at the Aga Khan University Hospital in Karachi, Pakistan, collected a case series of 34 patients with GBS. The ages of the patients ranged from 3 to 70, and 62% were male. In 35% of the cases there was a preceding gastrointestinal infection and in another 26% of the cases there was a preceding respiratory infection. Breathing failed in 56% of the cases, requiring mechanical ventilation. One patient died. Despite the frequently devastating nature of GBS, most patients improve, albeit slowly. Compiling a separate case series, investigators at the Centre for Rehabilitation Research in Orebro, Sweden, tracked the progress of 42 patients with this illness. Mechanical ventilation was necessary in just 21% of their cases. At 2 weeks, 1 year and 2 years after the onset of symptoms, 0%, 38% and 45% of patients had completely normal strength. At the same time points, 38%, 90% and 93% were able to walk 30 feet without assistance. Treatment is available for patients with GBS. Of course, when patients can't breathe on their own, using a mechanical ventilator to support respiration is a form of treatment and is usually life-saving. Two other treatments have been shown by randomized, controlled trials -- the gold standard method for evaluating a treatment -- to hasten recovery in GBS. One is plasmapheresis, also known as plasma exchange, in which the liquid portion of the blood (plasma) is separated from the blood cells. The blood cells are then returned to the patient's body, and the body produces more plasma on its own to replace the plasma that was removed. The reason plasmapheresis works is uncertain, but it probably removes damaging antibodies from the bloodstream. Infusing immunoglobulin into the patient's bloodstream is the other treatment of proven effectiveness. The immunoglobulin preparation contains antibodies pooled from a large number of healthy donors. These healthy antibodies presumably counteract the injurious antibodies produced in the GBS patient. One might think that two treatments -- plasmapheresis and immunoglobulin infusion -- administered together or in succession would be better than just one, but that is not the case. A study showed that the two treatments in combination were no better in hastening recovery than one treatment. (C) 2006 by Gary Cordingley |
