Study Group Notes - Chapter 57 – Spinal Cord Vascular Disease

 

Vascular anatomy of spinal cord:

 

• Embryonic arterial supply derived from radicular arteries entering at each spinal level, dividing to follow dorsal and ventral roots
• Ventral roots join to form anterior spinal artery
• Irregular anastomoses in posterior form paired posterior spinal arteries
• Circumflex arteries (arteria vasocorona) connect anterior and posterior systems

 

 

 

 

 

 

 

 

• Development, 5-8 radicular arteries become predominant
• Great artery of Adamkiewicz follows a lower thoracic or upper lumbar nerve root, and supplies the lower thoracic cord and lumbar enlargement
• Lower segmental arteries supply the sacral cord, conus medullaris, and cauda equine
• Plexus from branches of ascending cervical and vertebral arteries supplies cervical and upper thoracic cord
• Traditionally, midthoracic cord considered most vulnerable, but new studies find lumbosacral cord moreso

 

Anterior spinal artery à anterior sulcal artery à supplies spinal grey matter, anterior and lateral funiculli, each to only one hemicord, spacing proportional to numbers of neurons at cord level

i.e. thoracic segments have greatest distance between arteries

 

Posterior spinal arteries à penetrating branches à supplies dorsal columns and extreme dorsal horns (1/3 of cord in cross-section)

 

Circumflex anastomotic vessels à superficial white matter

 

• Venous system parallels arterial supply.
• Radial veins à coronal plexus
• Deep parenchymal veins à central sulcal vein in median fissure (from both hemicords)
• Sulcal veins have intersegmental anastomoses
• Posterior median spinal vein is prominent within the extramedullary venous channels
• Vena radicularis magna – drains everything at the level of the lumbar enlargement
• Posterior radicular veins most prominent in cervical levels
• Venous blood from cord enteres epidural and paravertebral venous pexuses to form a valveless system from sacrum to occiput (Batson’s plexus)

 

Spinal cord ischemia:

 

• <1% of all acute strokes

Clinical presentation and course

• Weakness, numbness, pain, urinary complaints
• Can progress over hours, or suddenly
• Vulnerable thoracic cord à paraparesis more common than quadriparesis
• Numbness and paresthesias parallels (sometimes precedes) weakness
• Radicular back pain common
• Visceral referred pain
• Urinary retention (or bladder/bower incontinence after initial spinal shock)
• Examination: flaccid paresis, decreased reflexes… develops into spasticity, hyperreflexia, upgoing plantars if lesion above lumbar spine
• Posterior spinal artery syndrome rare – preserved strength and reflexes
• Sensation:
  • ASA – impaired pain and temperature
  • PSA – impaired touch, vibration, proprioception
  • Small lesion – partial Brown-Séquard syndrome - suspended dissociated sensory loss
    • loss of pain and temp over the segment, preserved sensation above and below lesion
• Course is variable
  • TIA of cord lasts 15 minutes
  • Slowly progressive myelopathy from chronic constriction described
  • Infarction in minutes, pain in hours (major disabling factor)
  • Return of function <24 hours is good prognosis for recovery

 

Investigations

• MRI is imaging process of choice, but can be normal despite symptoms
• Typically shows cord enlargement, T2 hyperintensity (8h – several days), long term atrophy
• Signal enhancement can be double dots (“owl’s eyes”) in the anterior horns, H-shape of central grey matter, or diffuse pattern involving grey and white
• Involvement of vertebral body if segmental artery involved
• CSF protein can be elevated, pleocytosis is rare

 

Causes

• Typical causes:
  • Regional hemodynamic compromise – from disruption of aorta, most common from AAA repair
  • Systemic hypotension – especially lower cord, often associated with encephalopathy
  • Occlusive vascular disease – e.g., atherosclerotic plaques, hyalinization – intermittent claudication
  • Thromboembolism – e.g., rheumatic heart dx (mitral valve), bacterial endocarditis, atrial myxoma
  • Endovascular procedures – e.g., therapeutic renal or bronchial artery embolization
  • Fibrocartilaginous (intervertebral disc) embolism – from ruptured disc, F>M,
  • Vasculitis – radiotherapy can affect arterioles, meningovascular syphilis
  • Arterial dissection
  • Thrombosis – Crohn’s, PAN, giant cell arteritis, sickle cell, intrathecal chemicals, angiographic contrast, postpartum state, intravascular neoplastic invasion, polycythemia rubra vera
  • Venous occlusion
• Abdominal aorta
  • Clamping aorta above renal arteries >20-30 minutes, or ligation of lower vessels puts cord at risk
  • AAA repair has 5-20% risk of neurological deficits
  • Aneurysmal aortic dissection also causes spinal ischemia – grey matter ischemia, white matter adequately supplied by longitudinal anastomotic network
• Vertebral artery dissection – can cause posterior cervical cord infarction
• Nonpenetrating aortic trauma – torsional occlusion of vessels à ischemia
• Percutaneous radiofrequency spinal rhizotomy à impaired autoregulation à local thoracic cord ischemia
• Decompression sickness – circulating nitrogen bubbles block small spinal arteries
• Foix-Alajouanine syndrome – subacute necrotizing myelitis
  • Stepwise spinal cord dysfunction with extensive thrombophlebitis of spinal cord
  • Associated with COPD or lung neoplasm, or end stage chronic venous HTN and congestion (dural venous fistula)

Treatment

• Supportive and reduce risk of recurrence
• Maintain BP, early bedrest, reverse causes (hypoTN, arrhythmia)
• Unclear use of acute thrombolytics or antithrombotics
• Minimize complications of autonomic dysfunction and immobility, PT/OT
• 20% mortality, more than minimal improvement in 35-40%

 

Spinal vascular malformation

 

• Normal/large arteries and enlarged tortuous veins without intervening capillary network
• Anson and Spetzler (1993) classification system:

1. Type I – dural AV fistula
   • 1A – single feeding artery
   • 1B – multiple feeding arteries
2. Type II – intramedullary glomus-type AVM
3. Type III – intramedullary juvenile-type AVM, more extensive than a glomus-type AVM, with extramedullary and extradural components
4. Type IV – intradural, extramedullary (perimedullary) AV fistula
   • IVA, IVB, IVC – demotes progressively increased AV shunting from increasing number, size, and tortuosity of feeding arteries
• Other forms not in classification – cavernous angiomas, venous angiomas (developmental venous anomalies), epidural/paraspinal AVMs

 

Distribution and prevalence

• Prior to selective spinal digital subtraction angiography – often misdiagnosed as spinal tumours
• Frequency of reported spinal AVMs is 3-11%, likely more due to asymptomatic/misdiagnosed
• Usually lower thoracic and lumbar spinal, usually dural AV fistulas draining to surface of cord

 

Clinical presentation

• Often misdiagnosed for years
• Onset can be acute or insidious, with remissions and relapses
• Common initial complaints – pain, weakness, sensory symptoms
• Later complaints – bowel and bladder complaints
• Symptoms often associated with trauma, exercise, pregnancy, or menstruation
• Locomotor difficulties in 20% after 6 months of symptoms, 50% in 3 years
• Symptoms due to mass effect and ischemia. Epidural, subdural, intramedullary hemorrhage cause spinal cord compression
• Dural AV fistula rarely hemorrhages, but causes slowly progressive myelopathy à infarction
• Pain – local, radicular, diffuse, or combination
• Weakness – upper and/or lower motor neuron
• Spinal bruit is specific but uncommon
• Vascular malformations in skin sometimes associated
• Cobb’s syndrome – cutaeomeninospinal angiomatosis – dural and cutaneous angiomas in same dermatome
• Foix-Alajouanine – has been associated with end-stage dural AVF + thrombosis + venous infarct
• Spinal hemorrhage – typical symptoms of spinal SAH
  • Headache, meningeal infection, cord/nerve root damage
  • CSF pleocytosis and high protein
• AVM or dural AV fistulas à increased local venous pressure à decreased perfusion pressure à ischemia
  • This explains symptomatic relief from ligation of feeding vessels
• DDx – neoplasm, herniated disc, MS, intracranial SAH, subacute combined degeneration, meningovascular syphilis, transverse myelitis

 

 

 

 

 

Investigations

• MRI with contrast enhanced MRA is test of choice
• Intramedullary AVM
  • Intramedullary low signal with surrounding normal cord, focal cord enlargement, serpentine signal voids in subarachnoid space.
  • MRA helps detect the feeding arteries
• Dural AV fistula
  • Slight enlargement of cord, cord hypointensity on T1, central hyperintensity on T2, scalloping of cord, enhancement of cord on T1
  • Findings non-specific and same as neoplasm, infection, or ischemia
  • Detecting blood flow-related abnormalities important – flow voids in T2, intradural serpentine enhancement on T1 extending >3 vertebral levels, MRA
  • Selective catheter angiography is definitive gold standard, but invasive and highly tedious

 

Treatment

• Surgical resection and/or angiographically directed embolisation of malformation

 

Spinal hemorrhage

 

• Usually sudden and painful, related to trauma or vascular malformations

 

Subarachnoid hemorrhage

• Spinal SAH is <1% of all SAH
• Most common cause is spinal angioma (10% total)
• Others: coarctation of aorta, rupture of spinal artery, mycotic or other aneurysms of spinal artery, PAN, spinal tumours, LP, blood dyscrasias, therapeutic thrombolytics and anticoagulants
• Presentation:
  • Sudden onset severe back pain localized near level of hemorrhage
  • In minutes, diffuse pain and meningeal irritation
  • Multiple radiculopathies and myelopathy
  • Headache, cranial neuropathies, decreased LOC – from diffusion of blood above foramen magnum
  • CSF grossly bloody, high ICP, papilledema
• Diagnosis:
  • Clinical suspicion important
  • Exam: spinal bruit, cutaneous angioma, sensory level, collagen vascular disease, septicaemia

 

Hematomyelia

• Intramedullary spinal hemorrhage, usually direct spinal cord trauma or hyperextension of cervical cord
• Spontaneous hematomyelia – bleed of spinal vascular malformation, tumour, or syrinx, bleeding diathesis, anticoagulant drugs, venous infarction
• Disrupts grey matter > white matter
• Not associated with hypertension or amyloid angiopathy
• Presentation:
  • Spinal shock, sudden severe back pain, radicular pain
  • Eventually spasticity below level of lesion, fasciculations, atrophy, areflexia
• Laminectomy with drainage of hematoma, resection or tumour/vascular malformation if deficits incomplete or progressive

 

Spinal epidural (SEH) or subdural (SSH) hemorrhage

• SEH > SSH, but clinically indistinguishable
• SEH – more in men, and in childhood (cervical) or 50-60s (thoracic-lumbar)
  • Can be spontaneous or from mild trauma, after LP or epidural anesthesia, esp if anticoagulated
  • Blood dyscrasias, thrombocytopenia, neoplasms, vascular malformations also
• SSH – more in women, especially 60s (thoracic-lumbar)
  • Hemorrhagic diatheses (anticoagulation, blood dyscrasias, thrombocytopenia), trauma, LP, vascular malformation, spinal surgery
• Presentation:
  • Severe back pain at level of bleed
  • Myelopathy or cauda equine syndrome with motor/sensory levels develop hours-days
  • Rapidly decreasing platelet count or <20,000 platelets/uL are at risk for LP (need transfusion first)
  • CSF – normal, xanthchromic, or increased protein
  • MRI – delineates hematoma in the dura
  • MRI+Gad/MRA – underlying vascular malformation
  • CT myelography is alternative if patient unstable – filling defect or blockage of contrast flow
    • Does not distinguish SEH from SSH
  • Laminectomy to evacuate clot ASAP, for better prognosis of recovery to minimize preop deficits