General
- Aka
- Type II AVMs
- “Glomus” AVM
- True AVMs of the spinal cord parenchyma
- Similar to cerebral AVMs
Numbers
- Affect men and women equally
- Mean age of presentation in 20s
Location
- Feeding arteries are from
- Posterior spinal artery
- Anterior spinal artery
- Intervening nidus
- Drainage veins
- Coronal venous plexus.
Classification
Diffuseness
- Compact
- Diffuse
- Mixed types
Flow rate
- High
- Characterized by the remodelling of vessels
- Hypertrophy of arteries,
- Development of aneurysms
- Rodesch et al., 2002: 31.6% incidence of arterial aneurysm
- Development of venous pouches.
- They are more often seen in children and patients with HHT.
- High vascular stress → increase in intramedullary or subarachnoid haemorrhage.
- Ischaemic myelopathy or symptoms resulting from neural compression by dilated vessels.
- Neuropathic pain (30%).
- Low
Natural history
- For incidentally discovered lesions
- Gross 2013
- 50% of patient present with haemorrhage
- Annual haemorrhage rate of
- 4% no previous haemorrhage
- 10% with previous haemorrhage
Clinical features
- Acute haemorrhage
- Steal phenomenon → progressive myelopathy
Radiology
Treatment
- Partial treatment might be better than no treatment
- Endovascular treatment
- Esp those fed primarily from the ASA.
- Aims
- Alleviate symptoms of ischaemia, mass- effect
- Reduce risk of haemorrhage.
- Agents
- Onyx or NCBA glue to treat nidus
- Coils may be used to treat venous pouches, ectasia, and aneurysms.
- Risk
- Inadvertent migration of embolic materials with resultant ischaemic injury due to complex angioarchitecture
- Recanalization was significantly more likely after poly- vinyl- alcohol (PVA) particle embolization (17%) compared to Onyx or NCBA glue (0– 11%).
- Microsurgery
- Surgical extirpation is an effective treatment in selected cases
- 2D angiotomography
- Planning the surgical approach
- Morbidity is determined mainly by the location of the malformation and the difficulty accessing it.
- The principles of surgical excision are similar to operating on the cranial homologue but certain nuances of technique merit comment.
- Low- flow lesions they may be advantageously approached from the venous side without the same fear of haemorrhage or congestion in the cord.
- Excessive pial dissection may be avoided and elements of the shunt are divided ‘in- situ’ rather than attempting complete extirpation of every component of the malformation.
- Most lesions are approached posteriorly or posterolaterally.
- Interruption of arterial side of AVM first
- Intraoperative neurophysiological monitoring → alterations in the motor tracts anteriorly
- Delta waves
- Motor evoked potentials
- Radiosurgery
- Indicated when microsurgery and endovascular surgery fail
- They pose challenges not encountered with their cerebral counterparts.
- Respiratory movements
- Facilitated by modern image guidance systems.
- No information about cord toxicity treatment
Outcomes
- Gross 2013 meta analysis
- Complete obliteration rates
- 78% for surgery
- 33% endovascular
- Long-term clinical worsening
- 12% for surgery
- 13% for endovascular treatment
- Complete obliteration resulted in no haemorrhages
- Partial surgical treatment
- The annual haemorrhage rate was 3% (95% CI: 1%-6%);
- Partial endovascular treatment.
- No haemorrhages were reported over 196 patient-years after — Or no one reported any rebleed
- Long-term Aminoff- Logue scale
- Surgery
- Gait scores were improved or stable in 93%
- Micturition scores the same or better in 94%.
- Endovascular and surgical outcomes at ten years similar
- Kalani 2016 and Hila 2003
- Complete obliteration: 0-19% at 3 years
- None had post-treatment hemorrhagic events.
- If not complete obliteration, significant volume reduction was noted at 3 years