dissection.md 8.32 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133
# dissection leading to stroke

## definition/mechanism

* dissection = separation in arterial wall layers resulting in blood seeping in = false lumen
    * from intimal tear, rupture, or vaso vasorum pathology

## location categories
* extracranial/cervical
    * anterior / carotid - mainly internal carotid artery (ICA)
        * ICA usually 1.5-3cm distal to carotid bifurcation to base of skull
    * posterior / vertebrobasilar - mainly vertebral artery (vert)
        * usually at C1-2 where mobile but tethered leaving transverse foramen & turns sharply to enter foramen magnum
* intracranial - less common, generally of MCA or basilar

## epidemiology
* extracranial dissections (much from Mayo Board review):
    * ~2% general population stroke, but ~10-25% strokes in younger than 45
    * ~50% with identifiable trauma / predisposing event
    * ICA: common age range of late 30s or early 40s with possible female predominance

## mechanisms / pathogenesis
* provocation: traumatic vs. spontaneous (may often be unclear)
* provocative factors / trauma
    * ICA + vert:
        * forceful/violent-coughing/Valsalva (e.g. childbirth), direct head/neck trauma (does not have to be severe), whiplash/neck-extension - event may be precede symptoms by days
    * vert:
        * most common: rapid & extreme rotation of neck (e.g. chiropractic manipulation, turning head driving)
        * contexts could include: bouts of coughing or trauma to neck/head. atlantoaxial dislocations where vert can be stretched/kinked through transverse processes or C1-2
* spontaneous pathogenesis
    * ICA - uncertain
        * in most cases cystic medial necrosis not found on microscopy
        * may be evidence of disorganized media & internal elastic lamina - unclear if specific
    * ICA + vert: rarely predisposing connective tissue condition as per below
* aortic arch dissection (traumatic or spontaneous) may result in dissection of multiple other vessels - may have chest/back pain, hypotension, BP difference between arms
* intracranial dissection
    * generally no associated trauma, though uncommonly minor head injury, violent-coughing/Valsalva, cocaine

## associated predisposing conditions - low percentage
* connective tissues diseases (SMALL number of patients) - confer increased dissection risk:
    * fibromuscular dysplasia (most common of this subset) - see stroke article
    * vascular/type-4 Ehlers-Danlos (<2% of all cases)
    * Marfan
    * osteogenesis imperfecta
    * transforming growth factor (TGF) B receptor mutation = Loeys-Dietz syndrome
    * pseudoxanthoma elasticum = Gronblad-Strandberg syndrome
* cystic medial necrosis, reticular fiber deficiency, homocystinuria, ADPKD, alpha-1 antitrypsin deficiency, segmental mediolytic arteriopathy, RCVS, cervical artery tortuosity, atherosclerosis
* atlantoaxial dislocations including odontoid hypoplasia
* with some/many of above association is tentative: may not be greater than expected for chance alone - caveat re suspicion as per workup section

## symptoms /signs
* vertebral
    * cervicooccipital pain & brainstem signs - variable w possibilities including
        * PICA blockage / lateral medullary syndrome
        * medial medullary syndrome
        * spinal artery occlusion: possible associated face-sparing hemi/quadri-plegia
        * subclavian steal if subclavian blockage proximal to L vert origin: L-arm-exercise-induced basilar insufficiency (w possible associated headache & arm claudication/pain)
        * proximal cervical vert occlusions may be compensated by anastomoses from other arteries: thyrocervical, deep cervical, occipital (or "reflux" from circle of Willis)
        * may be NO symptoms if on one side occlusion in vert proximal to PICA origin & retrograde flow via well-open/sized contralateral vert
        * may have fluctuations over minutes to hours
* internal carotid artery dissection
    * symptoms
        * may have unilateral head/face fluctuating achey pain days preceding stroke symptoms
            * this pain might be markedly steroid responsive
        * may have neck pain over dissection site
        * less common: amarousis fugax, lightheadedness, syncope, facial numbness
    * signs
        * Horner's ("painful Horner's usually due to underlying structural lesion" - Adam and Victor's)
        * less common: cervical bruit
        * possible cranial nerve involvement (close proximity / small branch feeders): vagus, spinal accessory, hypoglossal
* intracranial
    * fluctuating symptoms, ischemia relatable to vessel
    * severe unilateral pain: retroorbital for MCA, occipital for basilar, occipital/supraorbital for vertebral

## complications / associations
* ischemia as per above (TIA/stroke)
* dissections may extend from neck distally into cranial vessels
* vert: pseudoaneurysm
    * mostly intracranial type w associated risk of rupture leading to SAH
    * cervical type: low rate of associated rupture/ischemia
* rare association with RCVS (unclear etiologic relationship; vert > carotid)
* subset of intracranial dissections with subarachnoid hemorrhage

## diagnosis

* double lumen evident on CTA/MRI/MRA, possible detection of anterior dissection on carotid US (limited)
* "string sign" possible: variable-length irregular elongated narrow dye-column, w upper-end tapered occlusion or outpouching (Adams and Victor's)

## workup:
* given tentative associations and low proportion of patients found to have connective tissue or vascular disorder is low, additional testing not generally recommended unless specific higher suspicion
* factors that may increase clinical suspicion for connective/vascular disease as generator:
    * multiple extracranial vessel spontaneous dissection
    * widespread vascular toruosity
    * family history, joint hypermobility, multiple joint dislocations, translucent skin, poor wound healing, easy bruising, unusual scars

## treatment: non-definitive/varied
* extracranial:
    * acute management
        * tPA should NOT be withheld for otherwise eligible patients with associated acute ischemic stroke
        * reperfusion - endovascular re-opening of occluded vessel if rapid may be beneficial via angioplasty and/or stenting (risk of extending dissection)
    * subacute/chronic management
        * with associated acute ischemic neuro symptoms:
            * disagreement whether antiplatelet or anticoagulation therapy optimal, but some evidence of equivalent effectiveness - CADISS trial (via Wein et al. 2017)
            * if anticoagulation: LMWH or warfarin for ~6 wks to 3 months, with use of repeat imaging to guide duration (generally done even though not clearly evidence based; continuum 2/2017)
            * scenarios w relatively more support for anticoagulation (via Adams and Victor's) - non-definitive based on evidence
                * basilar artery thrombosis w fluctuating deficits
                * impending carotid artery occlusion from thrombosis or dissection
            * if carotid occlusion - "role of anticoagulation is less clear" (Adams and Victor's)
        * without associated acute ischemic neuro symptoms
            * antiplatelet therapy
        * if anticoagulation is used for non-occlusive dissection:
            * generally discontinuation months to ~1 yr when repeat angiography demonstrates patent lumen or >=50% normal diameter w smooth wall
* intracranial
    * lack of evidence for anticoagulation
    * antiplatelet therapy
* consider steroids for pain

## prognosis with intracranial/extracranial dissection
  * "complete or excellent recovery" in ~70-85%
  * disabling deficits ~10-25%, death ~5-10%
  * however, if complicated by stroke: ~25% mortality & most others w significant impairment
  * reported recurrence rates broad, but ischemia specifically from recurrent dissection thought low
      * extracranial dissection per CADISS trial: low frequency recurrent events ~1-3%
      * recurrent ischemic symptoms (not clearly specifically from dissection) ~0 to 13% (uptodate)

## refs
* Adams and Victor's
* Mayo Board Review
* continuum 2/2017
* uptodate:
    * Spontaneous cerebral and cervical artery dissection: Clinical features and diagnosis
    * Spontaneous cerebral and cervical artery dissection: Treatment and prognosis
* "Canadian stroke best practice recommendations: Secondary prevention of stroke, sixth edition practice guidelines, update 2017." Wein et al. International journal of stroke, 2017. PMID: 29171361. DOI: 10.1177/1747493017743062