[Apparelyzed]

The Incomplete Spinal Cord Injury Syndromes
by Wise Young, Ph.D., M.D.
W. M. Keck Center for Collaborative Neuroscience
Rutgers, the State University of New Jersey, Piscataway, NJ 08540-8082
last updated: 30 June 2006


• Brown-Séquard Syndrome. This was described by Charles Édouard Brown-Séquard in 1861 at the Institute of Neurology at Queen's Square (Source). This results from an injury to one side of the spinal cord, preserving one side. The symptoms are a classical demonstration of the separation of the sensory pathways for pain/temperature and proprioception. Those with the Brown-Séquard syndrome lose proprioception and have volutnary motor weakness on the side of the spinal cord injury and loss of pain-temperature on the other side. However, a majority of people with this injury recover ability to walk because the locomotor pattern generator can be activated by descending axons from both sides of the cord and the generator itself than can initiate bilateral walking.

• Central Cord Syndrome. This is a cervical spinal cord injury where the arms appear to be more affected than the legs. For a long time, this was thought be related to an injury that primary affected the middle of the spinal cord with preservation of an outer rim of white matter. However, in the 1990's, Richard Bunge and his colleagues challenged this concept with their examinations of the spinal cord of people with so-called central cord syndrome, showing that this was an injury to the corticospinal tracts, which are located in the lateral columns of humans. The arms are more dependent on the corticospinal tract than the legs and therefore are more effected. A majority of people recover substantially from central cord syndrome.

• Posterior Cord Syndrome. This is condition due to damage to the posterior part of the spinal cord, affecting proprioception and often leaving some motor function. While it is said to be quite rare because the original description stipulated that the patient has lost proprioception, light touch, and voluntary motor control but retains temperature-pain function (Source). However, in my opinion, a much more reasonable definition is a person who has lost proprioception but retains temperature-pain sensation and motor function. If so, in my experience, this is quite a common condition. Many people with so-called "incomplete" spinal cord injury recover significant motor function in their arms and legs but they do not recover their proprioceptive function.

• Anterior Cord Syndrome. This is a relatively rare condition that has been attributed to the damage to the anterior part of the spinal cord, affecting motor function but leaving sensory function largely intact. Originally described by Schneider in 1951 (J. Neurosurgery 8: 360-370), who presented two cases of patients who had ruptured, herniated discs and bone fragment in the spinal canal that pressed on the front (anterior) of the spinal cord. He decompressed these patients and they recovered substantial motor function. The reason why this is a relatively rare condition is because a majority of such patients recover substantial motor function due to preservation of the corticospinal tracts in the lateral columns. However, people may have difficulties walking due to the loss of the vestibulospinal and reticulospinal tracts that run in the anterior column and are responsible for standing and locomotor reflexes. Thus, such people may be able to voluntarily move their legs but do not walk as well.

Very few people have pure anterior, posterior, central, or Brown-Sequard syndromes. Most have mixtures. However, all of these conditions are "incomplete" spinal cord injuries and most people can recover substantial motor function. A recent study by Dobson, et al. (2006) indicated that over 90% of people with "incomplete" spinal cord injury can recover walking with intensive exercise. The study was designed compare the effects of treadmill weight-supported ambulation training and more standard rehabilitation overground and standing. To their surprise, they found that both courses of therapies resulted in 90% of the people walking. These are all in people during the first year after injury.

These results are very surprising because the Model Systems Database which have tracked over 25,000 patients since the 1970's suggest that only about 40% of people with "incomplete" spinal cord injuries recover ability to walk. While studies are still going on to assess whether ambulation training will restore walking in people who have chronic "incomplete" spinal cord injury, already several groups have reported that weight-supported treadmill ambulation training of people who are more than 10 years after "incomplete" spinal cord injury can recover independent locomotion. Since more than half of spinal cord injured people are "incomplete", this suggests that intensive ambulation training can restore walking in a majority of people after spinal cord injury.

One question is why this was not discovered earlier. Well, at least 40% of the people with incomplete spinal cord injury did know and did recover. One possibility is that this resulted from physicians telling patients that they will not recover walking and people did not make an attempt to undergo intensive ambulation training. A second possibility is that this may be a result of the widespread use of methylprednisolone which began in the early 1990's and continues today. A third possibility is that better emergency care and earlier decompression of injured spinal cords may be making "incomplete" patients more incomplete.

It is important to note, however, that many people who recover walking, e.g. walking quads and walking paras, are not "normal" walkers. Many can walk stand and walk for only short distances. Walking may be strenuous and quite wearing. Many people lack proprioception and both unsteadiness and poor balance often limits ability to walk on different kinds of surfaces, grades, and conditions. One important discovery about five or six years ago was the discovery that electrical stimulation of the L2 cord (around T10) will activate the locomotor pattern generator. Several studies have shown that the L2 stimulation allows people to walk longer distances with less effort. This is likely to play a major role, in my opinion, in locomotor training in the future.

Paradoxically, it seems that walking is probably the most likely function to return after incomplete spinal cord injury in the cervical and upper thoracic levels. Because the locomotor pattern generator is usually intact in such people and very few descending axons are necessary and sufficient to activate walking, probably more than half of people will recover locomotion after spinal cord injury. However, many people continue to have some bladder problems, resulting from bladder spasticity and detrusor-sphincter dyssynergia. Sensory loss may contribute to sexual dysfunction. Spasticity is often a significant problem. Walking therefore is often laborious, inefficient, and less useful.

In summary, there are four different incomplete spinal cord syndromes. These syndromes are often not talked about today because most incomplete spinal cord injuries are mixtures of the four syndromes and most people recover substantially. Although for many years, less than half of such people recover locomotor function, recent studies suggest that as many as 90% of people with incomplete spinal cord injuries will be able to recovery ability to walk with intense ambulation training. This is in large part because the locomotor pattern generator is usually still intact and relatively few descending axons are necessary and sufficient to activate the neural circuitry for walking. However, the walking is often difficult, limited, and laborious.

This article was reproduced with kind permission of Wise Young, Ph.D., M.D.
The original article can be found at: http://sci.rutgers.edu/forum/showpost.php?...p;postcount=341