What is Spinal Cord Infarction?
Understanding the structure and function of the spinal cord is crucial when diagnosing and treating a medical condition called spinal cord infarction (SCI), which is when part of the spinal cord does not receive enough blood. The spinal cord has 31 pairs of nerve roots that come from the neck (8 pairs), chest (12 pairs), lower back (5 pairs), and base of the spine (1 pair). The front two-thirds of the spinal cord controls movement and sense of pain, while the back one-third helps with balance and understanding position. The side area of the spinal cord contains pathways that connect the spine and brain.
The spinal cord’s blood supply comes from one front spinal artery (ASA) and two back spinal arteries (PSA) that run down the length of the cord. They start from arteries in the neck and connect in complex patterns to provide blood to the different nerve pathways in the cord. The ASA supplies blood to the front part of the spinal cord, while the PSAs can start from other arteries and use additional arteries for supply. In most people, one of the arteries from the middle and lower sections of the back plays a major role in supplying the ASA, and it gives blood flow to the lower chest and lower spinal cord areas. This artery is known as the Adamkiewicz artery.
Due to many overlapping areas of blood supply, the spinal cord is less likely to be damaged by problems in the blood vessels. However, the exact pattern of blood supply can vary among people. The front two-thirds of the spinal cord and part of the back column get blood from the ASA, and the back one-third region gets its blood from the PSAs. One area in the spinal cord might have a mix of blood supply from both the ASA and PSAs, though there is no definitive evidence yet. The lower chest area of the spinal cord has a higher risk of blockage due to less blood supply and less overlap in the areas of supply.
The anterior spinal and medial posterior veins take care of draining blood from the spinal cord. Working together, they form a network of veins that surround the cord, in a similar way to the arteries. These veins lead into larger vein networks, which then transport blood to the two main veins in the chest and pelvis. However, because the spinal vein network doesn’t have valves, it can be more susceptible to infections.
What Causes Spinal Cord Infarction?
People can get a spinal cord infarct (a condition where blood supply to the spinal cord is interrupted, causing damage) at any age from childhood to old age. It typically happens most often between ages 50 and 70, with the majority of cases (65%) happening in the part of the spine near the lower back and chest. Some people also get it in the neck area, which can result in more severe symptoms like problems with the nervous system and upper body.
The causes of spinal cord infarcts can be different for children and adults. In children, it’s usually due to heart problems or injuries. In adults, diseases of the aorta (the main artery in the body) are the main cause. This could include hardening of the arteries, surgery on the aorta, or an enlarged aorta.
Having a history of heart disease can also make you more likely to develop a spinal cord infarct. Other risk factors include high blood pressure, smoking, high cholesterol, and diabetes. Some other conditions that can lead to a spinal cord infarct include spinal degeneration (or wear and tear), use of epidural or spinal anesthesia, disc herniation associated with pieces of the disc blocking blood vessels, tearing of the vertebral artery, surgeries that interrupt the nerves, low blood pressure, a heart embolism (when something like a blood clot travels to the heart), blood clotting disorders, inflammation of blood vessels, a type of spinal injury that can happen while surfing, and decompression sickness (also known as the bends).
Using cocaine, heavy lifting or straining, chiropractic manipulation, and slipped discs can also cause a spinal cord infarct and these are associated with a younger age of onset. Moreover, septic thrombophlebitis (inflammation of a vein caused by a blood clot that’s infected) can block blood in the spinal veins and lead to a type of spinal cord infarct due to lack of blood supply.
Risk Factors and Frequency for Spinal Cord Infarction
Spinal cord infarction (SCI), or the death of tissue in the spinal cord, is a relatively rare condition. This can be attributed to the spinal cord’s extensive network of collateral blood vessels.
- SCI is estimated to occur in 1% to 2% of instances of strokes caused by lack of blood flow (ischemic strokes) and in 5% to 8% of all the sudden onset spinal cord diseases (acute myelopathies).
- About 8% of patients with multilevel aortic disease (problems affecting different levels of the main artery carrying blood from the heart) may experience SCI.
- The risk of SCI is increased in patients who undergo surgery on their thoracoabdominal aorta (the part of the main artery that runs through the chest and abdomen), with rates seen as high as 33%.
- In a study among patients with a ruptured or dissected aorta, SCI occurred in one in 130 patients who underwent emergency aortic repair and one in 600 patients who had non-emergency surgical repairs.
- In a retrospective study of 164 patients with acute SCI, 5.5% were identified to have the condition due to fibrocartilaginous embolism (a blockage in the blood vessels of the spinal cord).
It’s important to note that studies on the prevalence of SCI are limited, given the rarity of the condition.
Signs and Symptoms of Spinal Cord Infarction
Quick detection of Spinal Cord Injury (SCI) is crucial and can be achieved with a detailed history examination and physical evaluation, in combination with neuroimaging. If SCI is suspected, doctors use various methods to manage the condition and try to prevent further injury. These methods can include increasing the patient’s blood pressure, draining some of the cerebrospinal fluid (CSF) to increase spinal blood flow, and maintaining stable blood pressure above a certain level.
- Performing detailed history examination and physical evaluation
- Utilizing neuroimaging for diagnosis
- Using hemodynamic support (increasing blood pressure)
- Performing lumbar drainage to lower the CSF pressure
- Maintaining optimal blood pressure above 90mm Hg
- Regular monitoring for improvement or complications over 12 to 48 hours
A study involving 49 patients undergoing endovascular repair for aneurysms in their chest and abdomen made use of continuous motor/somatosensory-evoked potential (a type of monitoring that involves stimulating nerves and recording responses), cerebrospinal fluid drainage (removing fluid surrounding the spinal cord), and use of iliofemoral conduits (tubes inserted in the groin area to allow for the passage of medical devices). These processes allowed for early prediction and treatment of spinal cord injury.
After any procedure, regular checks on the patient’s neurological health, checks on the brain’s function, and assessment of the patient’s communication, awareness, and motor skills are vital. This neurological check-up should be carried out right after the effects of anesthesia wear off, and should include assessment scales that follow guidelines by the American Spinal Injury Association. The patient may momentarily lose sensation in their legs after operation. Post-operation patients are also at a higher risk of having blood pooling in the epidural space (the space between the outer cover of the brain/spinal cord and the vertebral wall).
Many laboratory tests can be performed and would depend on the patient’s display of symptoms. Tests might cover deficiencies in copper, zinc, vitamin B12; and infections like Lyme disease, Chickenpox, and HIV, to name a few.
Some spinal cord injury cases would require a procedure called a lumbar puncture, which analyses the cerebrospinal fluid (the fluid around the brain and spinal cord). This can look at the amount of red and white blood cells, the level of protein and glucose, amongst others. An elevated protein level or white blood cell count might occur due to situations like blood clots, celiac plexus block (a nerve block to manage abdominal pain), and vasculitis (inflammation of blood vessels).
Imaging, such as X-rays, continues to be a valuable tool for diagnosing spinal cord injuries, even though the results can sometimes be equivocal. Magnetic resonance imaging (MRI), which uses a magnetic field and computer-generated radio waves to create detailed images of the body, is often employed to identify and pinpoint spinal cord injuries. Within the first day of spinal cord injury, Diffusion-Weighted Imaging (a type of MRI imaging) becomes much more sensitive. There may be no visible signs in the early stages, so a second MRI might be necessary days later.
Significant findings on an MRI have been associated with specific blood vessels being involved; these include spinal cord swelling (which leads to atrophy or wasting during the chronic phase), and different types of hyperintensities (bright spots) on T2 and T1 weighted images, and DwI images. If MRI cannot be used due to factors like epidural hematoma (bleeding in the space between the brain and the skull), or if the patient’s condition is unstable, a CT scan can be used. If there are structural changes or abnormalities shown in the imaging tests, an urgent neurosurgical consultation might be necessary; otherwise, supportive treatment is continued while other causes are investigated.
There are additional tests that might help confirm spinal cord injury or rule out other causes. Among these are tests involving imaging of blood vessels (magnetic resonance angiography, computed tomography angiography, full spinal magnetic resonance angiography, thoracoabdominal computed tomography angiography, digital subtraction angiography) and electromyography (a test that checks the health of muscles and the nerve cells controlling them).
Treatment Options for Spinal Cord Infarction
In instances where a person’s blood vessels are compressed or experiencing a sudden issue with the main blood vessel in their body, the aorta, they will likely need surgery right away. This aims to keep blood flow steady and safe. During operations on the aorta, doctors often manage the situation using lumbar drainage, a process where fluid is drained from the lower spine, and increasing blood pressure.
When it comes to spinal issues caused by the dissection or splitting of the vertebral artery, a blood vessel along the spine, treatment is typically centered on blood thinners. These help to reduce the chance of a clot that could interrupt blood flow. In addition, drugs that stop blood cells from sticking together, known as antiplatelet therapy, can be used along with the blood thinners.
There’s been a study where all the participants received antiplatelet therapy including common over-the-counter medications like aspirin and clopidogrel, a drug used to reduce the risk of heart disease and stroke. Physical therapy has shown to help improve outcomes for these patients.
In cases of vasculitis, a condition where the body’s blood vessels become inflamed, corticosteroids are often used. These are a class of drugs that can reduce inflammation.
Lastly, decompression sickness, a condition that can occur in divers, is usually treated with hyperbaric oxygen. This involves breathing pure oxygen in a room or tube that has pressure greater than normal air pressure.
What else can Spinal Cord Infarction be?
Some conditions can mimic the symptoms of Spinal Cord Injury (SCI) and can appear identical on MRI scans. These include:
- Cancerous transformation
- Slipped disks (disk herniation)
- Spinal abscesses (epidural abscesses)
- Blood clots in the spine (epidural hematoma)
- Multiple sclerosis
- Spinal tumors (spinal cord neoplasms)
- Transverse myelitis, an inflammation of the spinal cord caused by infections or autoimmune diseases
- Internal bleeding or tumors in the spinal cord (intramedullary hemorrhage or neoplasm)
To differentiate these possible conditions from SCI, doctors may need to conduct a thorough analysis of the spinal fluid (CSF analysis) and run a series of tests (paraneoplastic panel evaluation). In some cases, tumors or other conditions can compress the spinal cord and disrupt blood circulation, which can mimic the symptoms of SCI.
What to expect with Spinal Cord Infarction
Getting a timely diagnosis and treatment is crucial for improving the outcome and prognosis of Spinal Cord Infection (SCI). The good news is, SCI is reversible, and a full recovery can be achieved with prompt identification and proper management. The severity of any neurological deficits can generally determine prognosis.
In a study of 36 patients with acute spinal stroke, outcomes were generally favorable. Out of these, 23 patients (64%) experienced either complete or partial recovery, 12 patients (33%) had no recovery, 18 needed assistance to walk (50%), and 11 (31%) required a wheelchair at the time of discharge. The study noted that a favorable prognosis was associated with unilateral infarcts, which means a stroke affected only one side of the body.
A separate study observed patients with SCI who were enrolled within 10 days of the first symptom appearing. The study revealed that patients who initially had proprioceptive deficits or issues with sense of bodily movements and position were likely to have the worst outcomes. Half of the patients in the study also developed pain.
The long-term outcomes of SCI were also assessed in another study involving 30 patients. When comparing these outcomes to those of patients with cerebral infarction (a type of stroke), those with SCI showed lower mortality rates, higher re-employment rates but a more challenging functional outcome or restoration to normal activities.
Possible Complications When Diagnosed with Spinal Cord Infarction
After some spinal cord injuries (SCIs), patients might experience a persistent loss of ability to move and feel, known as motor and sensory modalities, which includes symptoms like tingling sensations (paresthesias) and paralysis. This condition can increase the risk of developing heart and lung diseases. Moreover, chronic pain, and issues with urinary and bowel functions are also common among SCI patients.
Furthermore, these patients may also report other secondary complications such as respiratory infections, muscle stiffness (spasticity), swings in blood pressure, and bedsores (pressure sores).
Common Complications:
- Persistent loss of motor and sensory functions
- Tingling sensations
- Paralysis
- Increase in risk of heart and lung diseases
- Chronic pain
- Urinary and bowel problems
- Respiratory infections
- Muscle stiffness
- Variable blood pressure
- Bedsores
Preventing Spinal Cord Infarction
The National Institute of Neurological Disorders and Stroke (NINDS) offers a broad range of resources for those living with spinal cord injuries. These resources can provide useful information and educational materials that can help you understand your condition better. It’s a good idea to check out everything they have to offer, such as clinical trials—research studies to evaluate medical treatments—patient organizations, and various publications concerning your condition.
Additional support and help from the wider community for patients and caregivers are available through groups like the Christopher and Dana Reeve Foundation, Paralyzed Veterans of America, and the United Spinal Association. These establishments work to provide aid and understanding to people coping with life after a spinal cord injury.
