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

At the age of 32 Sigmund Freud developed a new problem. Pricking and other unpleasant sensations had overtaken the skin on the outer side of his right thigh. Walking made his symptoms worse. The affected skin was exquisitely sensitive to touch and even the usual rubbing of his underclothes irritated the area.

Seven years later in 1895, when Freud wrote up his self-observations for a German medical journal, the abnormal sensations were still present, but had migrated. At first, the area of disturbance had been more noticeable near the top of the thigh, but gradually the abnormal sensations moved downward to a palm-sized area a hands breadth above the side of his knee.

When Freud squeezed a fold of skin in this area, it hurt more than it did in his left thigh. Although he could feel a pinprick as such, it also burned. Even so, individual spots within the zone of abnormal skin were insensitive to ordinarily painful maneuvers. He also noticed that temperature sense was impaired. Warm objects placed against the affected skin felt cooler than in unaffected areas. And although the original pricking sensations improved over time, his outer thigh had become generally less sensitive to usual stimulations.

Freuds physician, Josef Breuer, found that the affected skin was in the territory of the lateral femoral cutaneous nerve, a nerve that concerns itself with sensation only and has no muscular connections. Dr. Breuer concluded that Freuds symptoms were caused by damage to this nerve. Dr. Breuer also suspected that the nerve might be particularly vulnerable to injury in the groin near the front of the hip where it passes between strands of a ligament. As a result, he thought that wearing tight clothing might aggravate the condition.

Our understanding of this disorder has changed little in the 110 years since Freud wrote his report for Berlins Neurologisches Centralblatt, or in the 20 years since Francis Schiller, M.D., translated it into English for the American journal Neurology.

To set the record straight, Freud and Breuer were not the first to recognize this condition. Max Bernhardt of Germany first wrote about it in 1878 and in 1895 Vladimir Roth of Moscow named the condition meralgia paresthetica, a term still in use. This name is the sum of its three parts. Meros is Greek for thigh, algos is Greek for pain and paresthetica means unprovoked sensations. This entrapment neuropathy pinched nerve condition was one of the first to be recognized as such.

The lateral femoral cutaneous nerve is formed in the lower back from branches of the second and third lumbar spinal nerves which combine to form a single nerve on each side soon after emerging from the spinal column. The nerve passes through the interior of the pelvis and exits the pelvis near the outer border of the inguinal groin ligament before making a downward turn to run beneath the skin of the outer thigh.

The course of the nerve can vary from person to person and even from side to side in the same person. In about 25 of people the nerve splits into branches before reaching the inguinal ligament, and there can be up to 5 branches. This variability might make some people more vulnerable to nerve-injury than others.

Pressure within the pelvis, as from pregnancy, obesity and rarely tumors, can injure the portion of the nerve within the pelvis. And as Freud’s physician surmised, the nerve is particularly vulnerable to injury from external pressure at the inguinal ligament, as from corsets, wide belts and tight pants. However, a cause for meralgia paresthetica is not always found, as was apparently the case when Freud had it.

The nerve can also be injured during a wide variety of surgical procedures, including orthopedic, vascular, gynecological, abdominal, hernia and even stomach-stapling operations. In a recent series of spinal surgery cases in Taiwan, 60 out of 252 patients experienced meralgia paresthetica as a complication of the surgery. Fortunately, in all cases it resolved within two months.

Diagnosis of this condition is usually made from the history and the physical examination, with the key features being numbness and unpleasant sensations on the side of the thigh. Other conditions can mimic meralgia paresthetica, for example, a pinched spinal nerve in the lower back, or impairment in the nearby femoral nerve that also emerges from the pelvis at the inguinal ligament. Tests of muscle and nerve electricity–electromyography and nerve conduction studies–can help resolve ambiguous cases.

Treatment of meralgia paresthetica has not been studied by the gold-standard method of randomized, controlled trials involving a comparison group of untreated patients. So in choosing appropriate treatment all we have to go on are collections of cases published in medical journals. Because many cases turn out well without drastic treatments, conservative approaches are tried first. Weight loss, removal of tight garments, completion of pregnancy and simple watchful waiting can all be effective.

While awaiting a favorable outcome, symptoms can be managed with skin-patches containing a local anesthetic drug, anti-inflammatory medications, certain epilepsy and antidepressant drugs known to relieve nerve-pain, and local injections with steroids. Surgery to relieve the pinch is usually reserved as a last resort.

C 2005 by Gary Cordingley