Vascular Myelopathy

Disease/ Disorder

Definition

Vascular myelopathy (VM) refers to spinal cord injury (SCI) secondary to ischemia or hemorrhagic compression of the spinal cord.

Etiology

Etiologies of VM are most often secondary to tissue infarction caused by spinal cord ischemia (secondary to lack of blood supply) or by direct hemorrhage into the spinal cord.

Table 1: Etiologies of Spinal Cord Ischemia

Etiology	Causes
Procedure Related	Aortic Surgery, Vertebral Angiography, Renal Artery Embolization, Intra-Aortic Balloon Counterpulsation, Extracorporeal Membrane Oxygenation
Embolic	Cardioembolism due to Atrial Fibrillation, Endocarditis, Fibrocartilaginous Embolism, Decompression Sickness, Aortic Atheroembolism
Dissection	Aortic, Vertebral, Subclavian
Vasculitis	Systemic Lupus Erythematosus, Primary Angiitis of the Central Nervous System; Infectious Causes (Lyme disease, Varicella Zoster, Syphilis, Fungal)
Atherosclerotic	Segmental Artery Atherosclerotic Occlusion or Ruptures Plaque
Systemic Hypotension	Cardiac Arrest, Aortic Cross-Clamping, Intraoperative Hypotension
Vascular Malformation	Spinal Dural Arteriovenous Fistula, Spinal Arteriovenous Malformation, Cavernous Malformation
Hypercoagulable State	Malignancy, Sickle Cell Disease, Homocysteinemia, Disseminated Intravascular Coagulation, Antiphospholipid Antibody Syndrome, Hemophilia, Polycythemia Vera
Other	Radiation Induced Myelopathy, Pharmacologic or Medication Related Arteriopathy, Surfers Myelopathy

Table 2: Etiologies of Spinal Cord Hemorrhage

Etiology	Causes
Hematomyelia	Trauma, Vascular Malformation, Hypercoagulable States, Aneurysm, Anticoagulation Therapy, Radiation Therapy, Primary or Metastatic Tumors, Syringomyelia
Subarachnoid Hemorrhage	Trauma, Vascular Malformation, Aneurysm, Metastatic Tumors, Vasculitis, Hemangioblastoma, Spinal Ependymoma, Iatrogenic (spinal procedures, anticoagulation, antiplatelet treatment)
Subdural Hemorrhage	Trauma, Coagulopathy, Iatrogenic
Epidural Hemorrhage	Trauma, Coagulopathy, Iatrogenic

Epidemiology including risk factors and primary prevention

1. Spinal cord infarctions represent 1% of all ischemic strokes and account for 5-8% of all acute myelopathies.
2. VM occurs most often in women compared to men, and results in paraplegia and incomplete lesions, when compared with traumatic SCI.
3. In patients undergoing thoracoabdominal aneurysm repair, the incidence of spinal cord ischemia is between 4% and 16%, depending on the type of aneurysm and repair.
4. Chronic hypertension, underlying atherosclerotic vascular disease, and Marfan syndrome are risk factors for aortic dissection.
5. Embolic infarction to the cord is rare, especially venous embolism.
6. Fibrocartilaginous embolism has been reported most commonly in young women.
7. Hemorrhage affecting the spinal cord is rare.
8. Spinal AVM/AVF, also known as Foix-Alajouanine syndrome, is the most common cause of hemorrhagic myelopathy. It occurs commonly in men and in those older than 40 years.
9. Spinal subarachnoid hemorrhage (SAH) accounts for less than 1% of all Spinal AVM/AVF.
10. Spinal epidural hemorrhage (SEH) occurs at least 4 times more commonly than spinal subdural hemorrhage (SSH).
11. SAH and SEH are more common in men, while SSH is more common in women. It is most predominant in the fifth and sixth decade, though SEH also has a peak during childhood.
12. Von Hippel Lindau is an autosomal dominant condition that can cause hemangioblastomas in the spinal cord. It is estimated that the occurrence of this condition is 1:30,000.
13. Epidural hematomas should be suspected in patients with new neurologic symptoms following spine surgery or epidural catheterization. Risk factors include older age, multilevel surgeries and anticoagulation.
14. Vasculitis-associated myelopathy is rare

Patho-anatomy/physiology

1. Vascular supply to the spinal cord is supplied by radicular spinal arteries originating from the aorta and vertebral arteries one anterior spinal artery (ASA), and 2 posterior spinal arteries (PSAs). 
2. The ASA supplies the anterior two-thirds of the spinal cord, while the 2 PSAs supply the posterior cord.
3. Vascular supply to the lower thoracic and lumbar region of the cord originates from a single large radicular artery, the artery of Adamkiewicz.
4. Paramedian vessels (arising from the ASA) and anastomotic vessels between the ASA and PSA penetrate into the cord to supply the gray and white matter.
5. Blood flow to the spinal cord is influenced by metabolic demands and perfusion pressure (mean arterial pressure minus intraspinal canal pressure), and it is highest within the gray matter.
6. Systemic hypotension or increased intraspinal canal pressure may decrease perfusion and put the cord at risk for ischemia.
7. With decreased perfusion pressures, watershed ischemia of the penetrating arteries can occur, often in the thoracic levels.
8. Spinal infarction syndromes, including anterior and posterior spinal artery syndromes refer to compromise of the respective arteries and lead to distinct patterns of neurologic presentation.
9. The degree and duration of hypotension necessary to produce infarction is not well understood.
10. Venous drainage consists of 1 anterior and 1 posterior spinal vein that drain into radicular veins, a paravertebral plexus, and finally into the azygos and pelvic venous systems.
11. The spinal veins contain no valves. Therefore, Valsalva and increased intra-abdominal pressure can lead to increased venous pressure and decreased spinal cord perfusion.
12. Aortic surgery to repair thoracoabdominal aortic aneurysms can cause either systemic or focal hypotension, leading to spinal cord ischemia.
13. Risks appear to be somewhat lower with an endovascular (versus open) surgical approach.
14. Other factors may include aortic dissection, aortic cross-clamping causing decreased arterial perfusion and increased spinal canal pressure, occlusion of radicular or other intercostal arteries (either by ligation, resection, or embolization), advanced age, and history of cerebrovascular disease.
15. The exact pathogenesis of fibrocartilaginous embolism is uncertain.
16. It may be related to neck trauma with axial loading or heavy exertion, producing high intra-disk pressure that leads to herniated intervertebral disk material to flow into the disk vasculature.
17. Most cases involve the cervical cord or upper thoracic cord.
18. Venous embolism infarction is primarily because of occlusion of the venous drainage of the cord causing high pressure.
19. AVM or fistulas are congenital abnormalities of blood vessels where arteries directly communicate with veins (bypassing capillaries), creating dilated vessels that can lead to high venous pressure and reduced spinal cord perfusion or hemorrhage into the cord.
20. They are typically located on the dural surface of the spinal cord, more commonly in the thoracolumbar (60%) and upper thoracic (20%) regions.
21. Hematomyelia or bleeding within the spinal cord can be secondary to coagulopathy, trauma, or AVM.
22. SAH may cause symptoms due to irritation within the subarachnoid space or blood dissecting into the spinal cord or along nerve root sheaths.
23. SEH and SSH cause compressive symptoms because of hematomas within these enclosed spaces.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

1. Spinal cord ischemic infarction generally presents with sudden onset of neurologic deficits. 
2. The pattern of deficits will depend on which arteries are involved (see table 3) and the neurologic level where it occurs.
3. Radicular pain is often an early presentation.
4. Other neurologic symptoms include loss of sensation (early), weakness (within minutes to hours), bladder or bowel dysfunction, sexual dysfunction, and reduced reflexes below the level of involvement (though hyperreflexia may later develop).
5. Lower thoracic and lumbar levels are commonly affected, and incomplete (often asymmetric) paraplegia is more common, often times in an ASA syndrome distribution.
6. Spinal hemorrhages are usually sudden and accompanied by pain (often localized to the back).
7. The most common presentation of a spinal AVM is a slowly progressive myelopathy, which may lead to a diagnostic delay.
8. Weakness may worsen with extension and improve with rest (exertional claudication).
9. Back or lower extremity pain occur in at least 20% of cases.
10. By the time of diagnosis, symptoms likely include asymmetric leg weakness, gait disturbance, sensory complaints, sphincter impairment, pain, and hyperreflexia.
11. If not treated, 50% of patients will be unable to walk within 3 years of onset.
12. Operative treatment has been reported to be successful in relieving motor deficits, gait, and bladder incontinence.

Table 3: Vascular Spinal Cord Syndromes

Syndrome	Tracks involved	Signs/Symptoms	Artery implicated
Anterior Cord	Corticospinal, Spinothalamic, Sympathetic	Bilateral loss of pain/temperature below lesion; Autonomic symptoms	Anterior spinal (ASA)
Posterior Cord	Dorsal columns	Bilateral loss of light touch, proprioception and vibration below lesion	Posterior spinal (PSA)
Complete Cord	Corticospinal, Spinothalamic, Sympathetic, Dorsal column	Tetraparesis or paraparesis; Bilateral loss of pain/temperature below lesion; Autonomic symptoms; Bilateral loss of light touch, proprioception, and vibration below lesion	Segmental
Hemicord (Brown Sequard)	Corticospinal, Spinothalamic, Sympathetic, dorsal column	Ipsilateral hemiparesis; Contralateral loss of pain/temperature beginning two dermatomes below lesion; Ipsilateral loss of light touch, proprioception, and vibration below lesion	Sulcocommissural
Central Cord	Corticospinal, Spinothalamic	Upper extremity weakness more than lower extremity weakness; Bilateral loss of pain/temperature only at level of injury or bilateral loss below lesion	Sulcocommissural, within the watershed between the ASA and PSA

Specific secondary or associated conditions and complications

1. SCI-related complications found in individuals with VM include neurogenic bowel/bladder, sexual dysfunction, pain, urinary tract infection, pressure ulcers, depression, and spasticity.
2. Comorbidities for vascular related SCI include hypertension, cardiovascular disease, diabetes mellitus, and atrial fibrillation.

Essentials of Assessment

History

1. There may be associated medical history of aortic, peripheral vascular disease, vasculitis, radiation therapy exposure near the spine, and coagulopathy.
2. Signs of myelopathy include motor weakness, sensory or gait abnormalities, pain, and spasticity, along with bowel or bladder dysfunction.
3. Specific syndromes are described in table 3.
4. Radicular pain may precede or accompany VM. Its location varies depending on the level of SCI. 
5. In cervical lesions, pain is interscapular radiating to the shoulder.
6. In more caudal lesions, pain may radiate to the abdomen or anterior thighs.
7. In conus lesions, buttock pain may be seen.
8. Severe tearing pain and abnormal distal pulses suggest aortic tear or dissection. However, 5% to 15% are painless, requiring a high degree of suspicion for this diagnosis.

Physical examination

1. Physical exams should include a comprehensive evaluation of muscle strength, sensation (including sacral), rectal examination and reflexes. The International Standards for Neurologic Classification of SCI (ISNCSCI) exam developed by the American Spinal Injury Association (ASIA) and the International Spinal Cord Society  has specific key muscles and sensory points that can be used to classify the neurologic level and completeness of the SCI (ASIA Impairment Scales A through E).
2. Exam should include possible SCI-related complications, such as spasticity, pressure ulcers, and contractures.
3. Ischemic myelopathy often presents with flaccid paralysis below the level of injury along with hyporeflexia and reduced rectal tone.
4. Bladder distension may indicate urinary retention.
5. A spinal bruit (overlying a spinal AVM) may be specific. Occasionally, nevus (moles) or angiolipomas are found.

Functional assessment

It is important to evaluate patients who have neurologic involvement for their ability to perform self-care and mobility tasks. Various functional evaluation measures can be utilized for individuals with SCI, including the Functional Independence Measure (FIM) and WeeFIM (for children), the Spinal Cord Independence Measure (SCIM), and the Walking Index for Spinal Cord Injury.

Laboratory studies

1. Complete blood count with platelets may be helpful to address systemic blood loss in patients with hypotension.
2. International normalized ratio or prothrombin time and activated partial thromboplastin time may help to exclude coagulopathy.
3. Specific lab tests may be done for vasculitic disorders.

Imaging

1. Magnetic resonance imaging (MRI) of the spinal region is the preferred test to confirm the presence and location of ischemia, AVM, or hemorrhage, or to rule out other nonvascular etiology. T2-weighted images are more sensitive for acute ischemic lesions.
2. MRI techniques such as magnetic resonance angiography (MRA) allow visualization of flow, better vascular anatomy, and intramedullary pathology, and are a good screening modality, especially for AVM.
3. MRI findings consistent with fibrocartilaginous emboli include spinal cord edema with a prolapsed disc space at the corresponding level.
4. Myelography can diagnose AVMs (tortuous vessels on the cord’s surface).
5. Spinal angiography remains the diagnostic study of choice for AVM and may be helpful in delineating the size, location, configuration, and blood flow of the malformation.

Supplemental assessment tools

With hemorrhagic etiology, lumbar puncture can reveal gross blood, increased opening pressure, and increased protein within the cerebrospinal fluid (CSF)

Early predictions of outcomes

1. With ischemic myelopathy, more complete motor/sensory deficits (ASIA Impairment Scale A or B), extensive ischemic MRI changes, loss of bladder function or proprioception loss are associated with a worse prognosis for functional improvement.
2. In studies of individuals with nontraumatic SCI, older age, higher neurologic level of injury, and greater completeness of injury have been shown to correlate with poorer outcomes.
3. Acute dissection of the descending aorta is often a catastrophic event and is associated with a high mortality (10% to 50%).
4. Because upper cervical cord levels are involved in embolic ischemia, mortality is relatively high.
5. Outcome studies have noted recovery of motor function more than sensory or sphincter function and poor ambulation potential in those without early lower extremity movement or with proprioceptive deficits.
6. The majority of spinal dural AVM patients experience either stabilization or improvement of symptoms following treatments.
7. The degree of preoperative impairment is the strongest predictor of outcome.

Environmental

Depending on the neurologic level and completeness of injury, modifications may be needed to enhance functional independence within the home, school, or work environment. These may include adaptive devices, home modifications to ensure accessibility, attendants or aids, bath and toilet equipment, and assistive technology.

Social role and social support system

Given that individuals with vascular-related SCI may be older and with additional comorbidities, family, friends, and social support systems will be very important in allowing for return to independent living.

Rehabilitation Management and Treatments

Available or current treatment guidelines

1. Treatment of ischemic myelopathy includes supportive care, blood pressure maintenance, and reversal of causative factors (hypovolemia).
2. Improvement of spinal cord perfusion pressure can sometimes be achieved by vasopressor hemodynamic augmentation.
3. Several techniques have been studied to reduce the risk of spinal cord ischemia during aortic aneurysm surgical repair, including preoperative spinal angiography, intraoperative evoked potential monitoring, placement of lumbar drains, reimplantation of intercostal arteries, draining of cerebrospinal fluid, epidural cooling, and the use of distal aortic perfusion.
4. Although these interventions appear to improve outcomes, these have not been studied in a randomized or carefully controlled fashion.
5. The treatment of dural AVMs includes surgical ligation of the fistula or endovascular embolization (using polyvinyl alcohol beads or cyanoacrylate) with successful improvement rates between 30-90%.
6. Rapidly evolving endovascular procedures and techniques have made them the usual early interventional treatment of choice, although in some cases patients may later require surgery.
7. Focal radiation therapy (using a gamma or cold photon knife) is also a consideration.
8. Surgery may be necessary in spinal subdural and epidural hemorrhages to relieve pressures on the cord.
9. Treatment of spinal subarachnoid hemorrhage consists of bed rest and surgical resection of extramedullary angiomas, if present.
10. In coagulopathy-induced hemorrhage, reversal of the bleeding is important.
11. Consider vitamin K for warfarin-induced bleeds, protamine sulfate for heparin-induced bleeds, platelet transfusions for thrombocytopenia, and specific clotting factor concentrates or fresh frozen plasma for clotting factor deficiencies.

At different disease stages

1. Motor and sensory deficits below the level of injury can lead to functional impairment of mobility (bed, transfer, ambulation, wheelchair) and self-care activities (feeding, grooming, bathing, dressing). Physical and occupational therapy, along with the use of orthoses and assistive/adaptive devices, can help increase independence.
2. Impaired sensation and mobility may predispose to pressure ulcers. Patients and caregivers must be educated on pressure relief strategies and routine skin inspection. Pressure mapping along with appropriate mattress and wheelchair cushions may be required.
3. Bladder dysfunction (neurogenic bladder) may require a specific program designed to maintain continence, bladder emptying, and reduced incidence of urinary tract infections. Long-term urinary tract assessment may include lab studies, urodynamic testing, renal ultrasound, and urology follow-up.
4. Bowel dysfunction (neurogenic bowel) may require a specific bowel program (including medications, diet, timing, positioning, digital stimulation, manual disimpaction, and physical activity designed to maintain continence and reduce constipation and fecal impaction.
5. Neuropathic pain is common after SCI, either at or below the level of injury, and may require medications, and non-pharmacological interventions
6. Sexual dysfunction may be present, requiring education and discussion of treatment options.
7. Spasticity can be seen following VM. Treatment depends on how much it contributes to discomfort or interferes with function and may include range of motion, positioning, orthotics, medications, intrathecal baclofen pumps, local neuromuscular injections, or surgery.

Coordination of care

Rehabilitation strategies for individuals with VM should focus on a coordinated interdisciplinary team approach to maximize outcomes while minimizing complications.

Patient & family education

Patient and family education are important to manage ongoing medical and functional comorbidities and to prevent secondary SCI-related complications.

Cutting Edge/ Emerging and Unique Concepts and Practice

1. Non-invasive near-infrared spectroscopy is gaining popularity in the detection of spinal cord ischemia following aortic aneurysm repair.
2. A study performed by Archer et al in 2016 found that SCI can be significantly reduced by using proactive intraoperative and postoperative neuroprotective interventions that prolong spinal cord ischemic tolerance and increase spinal cord perfusion and oxygen delivery.

Gaps in the Evidence- Based Knowledge

1. The pathophysiology of spinal stroke is not nearly as well understood as cerebral infarction.
2. Specific rehabilitation outcomes after VM have not been studied as often as in those with traumatic SCI.
3. Future studies are encouraged to examine differences in complication rates, long-term functional outcomes, and mortality between these 2 SCI populations because of differences in demographics and comorbidities.

References

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Original Version of the Topic

William O. McKinley, MD. Vascular Myelopathy. 9/20/2013

Previous Revision(s) of the Topic

William O. McKinley, MD. Vascular Myelopathy. 8/16/2016

Author Disclosures

Kareen Velez, MD
Nothing to Disclose