When one hears the word stroke, what typically comes to mind is a “brain attack” with slurred speech or numbness and weakness of the right or left side of the body. Well, the spinal cord is considered part of the central nervous system and is truly a direct connection to the brain. All of the data received through nerve endings in our bodies passes through the spinal cord to be interpreted in the brain. Likewise, the messages our brain is sending to our bodies, both consciously and unconsciously (e.g. walk, run, write, speak; and digest food, breath, increase heart rate, etc.), travel through the spinal cord to our peripheral nerves.
The spinal cord is a vital structure that has its own blood supply, much like other organs, including the heart and brain. Just like the blood vessels supplying the other organs, the spinal arteries, especially the anterior spinal artery, can become occluded (i.e. blocked) resulting in spinal cord ischemia or infarction. The nerve information can no longer travel to and from the brain or the body freely; it is interrupted. This equates to a “stroke” of the spinal cord with resultant numbness, weakness, paralysis, as well as bowel and bladder dysfunction below the level of the infarction/stroke.
What causes a “spinal stroke”?
The most common cause of spinal stroke is the same as that for brain stroke or heart attack……atherosclerosis, an accumulation of cholesterol plaque in the arterial wall that ultimately blocks the artery. No blood flow means no oxygen or nutrients to the cells and tissues of the spinal cord resulting in them “starving to death.” There are other causes, as well; anything that compresses one of the supply arteries can block blood flow to a region of the cord and result in “stroke.”
Tumors, either primary or metastatic, can compresses blood vessels and other structures as they grow in the spinal region. Anterior disc herniations and disc ruptures or bone fragments from traumatic fractures of the vertebrae can compress blood vessels in the immediate vicinity.
Collections of pus from infectious processes can interrupt the blood supply either by compressing a vessel or disintegrating the blood vessel. Small pieces of blood clots (called emboli) can break-off from larger clots (called thrombi) and circulate through the bloodstream until they get “stuck” in a smaller vessel somewhere else in the body; the spinal artery is just one location. Other systemic diseases can result in vasculitis, or an inflammation of the blood vessel, that leads to clotting and occlusion of that vessel, and the spinal artery is just one of the vessels that can be affected.
Surgery and spinal stroke
Interestingly, inter-abdominal and spinal surgical procedures can also lead to spinal cord ischemia and stroke. Individuals undergoing repair of an aortic aneurysm or iliac-to-femoral artery bypass often require “cross-clamping” of the aorta above the level of the surgery. The “golden hour” referred to in heart attack victims can also be applied to other vascular ischemic conditions, like spinal artery ischemia; if complications arise and the cross-clamp time is too long, it can result in ischemia from which the patient may never recover, remaining paralyzed for life. Similarly, an aortic dissection can disrupt blood flow to the smaller arteries branching from the aorta to feed the spinal cord leading to ischemia.
Spinal surgeries take one of two approaches, anterior (going through the belly) or posterior (going through the back). Because of the proximity of all of the vital structures, including the major blood vessels, small errors or retained fragments can lead to occlusion or disruption of the spinal blood supply.
Who is at risk for spinal stroke?
Those individuals with risk factors for heart disease or brain stroke are also at risk for spinal stroke since they share a common etiology. This includes those individuals with poorly-controlled diabetes, high cholesterol or dyslipidemia, abnormal clotting of the blood, peripheral arterial disease or history of aneurysms.
What are the symptoms of a spinal stroke?
Most patients present with sudden, severe pain, much like a heart attack, in either the chest or the back or both. This pain is typically rapidly followed by numbness, or loss of pain sensation and temperature sensation, in the extremities below the level of the stroke. Because of the anatomy of the blood supply, vibration sensation and position sense are maintained in the affected region since the posterior region of the cord has a different blood supply. As the spinal stroke progresses over an hour or so, the extremities affected become weaker and weaker, often experiencing paralysis, and the bowel and bladder lose their innervation leading to dysfunction and incontinence. This is a fairly rapid progression, much different that other myelopathies.
What is the treatment?
Due to the relative rarity of this condition, not many studies have been done regarding treatments. Unlike “heart attack” or “brain attack,” there are no standards of care except for aspirin therapy and (potentially) anti-platelet therapy after the stroke has occurred. More often than not, there is a delay in diagnosing the condition due to the rarity of the condition and the need to confirm the diagnosis by a diffusion-weighted enhanced MRI of the spine, such that “clot-busting” agents are time-excluded from use. Treatments are then focused on preventing additional vascular events, preventing deep vein thromboses in the paralyzed limbs, preventing bladder infections and fecal impactions, preventing decubitus ulcers and soft tissue infections, and preventing the additional morbidity associated with paralysis. This is not a comforting thought!
We are blessed with today’s medical technological advances that allow for so many life-saving procedures and procedures that preserve body function, such as spinal surgery, vascular stenting procedures and epidural injections. Unfortunately, some of these procedures have increased the incidence of spinal strokes due to the nature of the procedures themselves. The current epidemic of obesity and metabolic syndrome is also indicative of more cases of diabetes and atherosclerotic vascular disease which, according to the law of probability, will increase the incidence of this potentially devastating medical condition.
Clinical Trials Underway
Do you know someone who has had a spinal stroke? What was his or her age? What might have precipitated the “attack”? Some individuals have been in their early 20′s when the attack occurred. Needless to say, this is truly devastating! With all of our advanced technology, we should be doing a better job of preventing, diagnosing and treating this condition. The National Institutes of Health (NIH) does offer clinical trials for this condition; please refer to their website for further information. ( http://www.ninds.nih.gov/disorders/spinal_infarction/spinal_infarction.htm)
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