The use of Acupuncture in patients with Neurogenic Claudication due to Spinal Stenosis

Abstract

Stenosis is derived from the Greek word meaning “narrowing of a normally larger opening”. Spinal stenosis occurs when the space around the spinal cord or the spinal nerves narrows and is primarily an aging process. It can occur in the cervical, thoracic or lumbar region. Due to the increasing life expectancy of the population, more people arc living to an age that this condition is likely to be symptomatic, so this problem will become more common in years to come. Unfortunately, lumbar spinal stenosis continues to be misunderstood and under-diagnosed, and many patients are never offered effective treatment for their symptoms.

Lumbar spinal stenosis can be caused by many conditions that decrease the space of the spinal canal. These can include: tumor, infection, and various metabolic bone disorders, such as Paget’s disease, diabetic neuropathy etc. These causes are much less common than degenerative lumbar spinal stenosis.

Therefore, the most common cause of lumbar spinal stenosis is degenerative arthritis. As with other joints in the body, arthritis of articular facet processes commonly occurs in the spine as part of the normal ageing process. This can lead to loss of the cartilage of the facet joints, formation of bone spurs (osteophytes), loss of the normal height of the discs between the vertebrae of the spine (degenerative disc disease), and overgrowth (hypertrophy) of the ligamentous structures. Each of these phenomena reduces the normal space available for the nerves (intervertebral foramen stenosis) and can directly generate a biomechanical stress and/or trauma on nerve tissues that cause neuropathy (trophic changes) and pain.

The symptoms of lumbar spinal stenosis are low back pain, weakness, numbness, leg pain and loss of sensation in the legs. In most cases the symptoms gradually worsen with time. This is because degenerative arthritis is a progressive disease that gradually becomes more severe.

Neurophysiologically, there are increasing evidence that ischemia of cauda equina or peripheral nerves plays an important role in the clinical picture of spinal stenosis. The intermittent compression , tension, torsion, shear and vibration forces that act on nerve tissue cause pronounced tissue changes, inflammation and swelling of the area. When further nerve tissue deformity occurs because of edema, immunologic, inflammatory and neurochemical agents affect the nerve fibers, the connective tissue and the blood vessels. Furthermore, compression or irritation of dorsal root ganglion (DRG) with formation of edema makes the DRG neurons sensitive to mechanical stimuli (hyperalgesia and allodynia). Light sensory stimulation in periphery excites the sensory neurons to generate spontaneous ectopic discharges with repetitive firing of axons that lasts for hours or days. According to many authors, these events result in reduction in axon transport, Wallerian degeneration and irreversible loss of nerve function. Other proposed mechanisms are cauda equina microvascular ischemia, venous congestion, axonal injury and / or intraneural fibrosis (Haldeman s 1999).

The most characteristic symptom of central or bilateral canal stenosis is neurogenic (intermittent) claudication, occurring in 94% of lumbar spinal stenosis patients. Physical examination findings are normal but careful examination shows diminished lumbar extension, loss of lumbar lordosis and forward-flexed gait, radiculopathy (with motor, sensory, and/or reflex abnormalities), asymmetric muscle stretch reflexes and focal myotomal weakness with or without atrophy.

Patients describe aching pain, paresthesias and heaviness in the legs that progress as they walk. They feel pain with ambulation and prone lumbar hyperextension. Their symptoms improve with trunk flexion, stooping or sitting, walking up hill, pushing a shopping cart or sitting on an exercise (stationary) bike. Unfortunately, such posture promotes disease progression and vertebral fracture. If left untreated the compression on the nerves leads to increasing weakness and loss of function of the legs. Moreover, it can cause loss of bowel and bladder control and loss of sexual function (Furman B.M., 2009).

Conservative treatment with pain-relieving agents seems to be the natural choice when symptoms are mild. Decompressive surgery to remove the bone and ligaments around the stenosis usually is recommended for patients with severe symptoms when conservative therapy has not provided adequate pain relief. Patients with moderate symptoms fall into a gray zone in which the most appropriate treatment is not obvious (Snyder D.L. et al, 2004). In these patients we should try various ways of conservative methods of treatment before we conclude that the best solution is surgery.

We are often asked by these patients (that fall in all three categories) if acupuncture can be effective in relieving their symptoms.

The question for us, doctors, is if acupuncture may play a complementary role in rehabilitation of patients with intermittent claudication due to lumbar spinal canal stenosis and what is the possible physiological mechanisms which will explain its action. Some studies (Inoue ct al. 2005) indicate that lumbar acupuncture stimulation can have an influence on sciatic nerve blood flow. The effect is dependent on regulating blood pressure in the system cauda equine / nerve root. Some authors support that acupuncture regulates the nerve homeostasis and balance vasodilator and vasoconstrictor (sensory and motor) nerve activity.

Other possible mechanism is through the anti-inflammatory effect of acupuncture. It is generally believed today, that the therapeutic (and partly analgesic) effect of acupuncture (to relieve and treat various inflammatory diseases and functional disturbances) is related to its ability to regulate hypothalamo - pituitary - adrenal (HPA) axis (Jcoung-WooKangk, 2004). There are reports suggesting that electroacupuncture (E/A) activates HPA axis and sympathetic adrenomedullary system and releases glucocorticoids, the final effectors of the HPA axis with potent anti-inflammatory properties (Liao et al, 1979, 1981). But, acupuncture effect on cortisol is complex. Some acupuncture points seems to increase cortisol level from 28 to 50% (GB 20, St 36, Per 6), some others to lower it (4 gates). However, there is no adequate evidence concerning the duration of the fluctuation of blood cortisol levels (homeostatic action) and which acupuncture technique has the most pronounced anti-inflammatory effect.

It was also reported that E/A modulates the secretion rate of catecholamines (substances with anti-inflammatory properties through 0 - adrenoreceptor activation) from adrenal medulla. This action relates to sympathetic activity due to trauma of the needle (Mori ct al. 2000, Sato at al, 1996) and the theory that each tissue injury causes increased sympathetic nerve activity.

In this present review differential diagnosis from vascular claudication and the management of symptoms of neurogenic claudication with acupuncture will be discussed. We will try to find out the most recent research work regarding the effect of acupuncture on nerve blood flow (vasa nervorum) and lumbar plexus blood flow. We will discuss the appropriate acupuncture points (site specific effect) and the techniques (mode specific effect) regarding spinal stenosis and neurogenic claudication.

To conclude, we will have to support that specific acupuncture techniques may be proved effective in conservative treatment of patients with neurogenic claudication due to spinal stenosis, when it is decided not to proceed with reconstructive surgery. The doctors, who will take the responsibility for treating such patients, should be aware of acupuncture limits, in order not to overestimate its potentials. They should also be familiar with the basic physiopathology of neurogenic claudication, so as to be able to recommend alternative solutions. Furthermore, we will promote the idea of team work, including in the rehabilitation team doctors specialized in acupuncture.