Vertebral Artery Dissection
September  2014

​​​​​​​​A 57 year-old male is applying for $1 million of life insurance. He has a remote history of a vertebral artery dissection occurring 7 years ago (at age 50). He evidently had an acute respiratory infection immediately before the acute onset of head and neck pain, which was quite sudden and severe. He also had just received a chiropractor adjustment for some neck pain, which had been an ongoing concern for several months. This onset of pain led to an ER visit.

MRA imaging revealed a dissecting left vertebral artery. Lumbar puncture was done, and there was no sign of a subarachnoid hemorrhage. The hospital course was uneventful with no significant neurological deficit. Anticoagulation was started without complications.

Repeat imaging at six months to reassess vascular status revealed that complete revascularization had occurred. Clinical evaluation for evidence of any connective tissue disease is mentioned as being negative. Since this event the applicant has reported no recurrent problems and has had no further evaluation. Records document that he remains on a baby aspirin daily and avoids any neck manipulation or any sports involving sudden or excessive neck motion.


Evaluating This Case

Two major questions arise when evaluating a case like this for mortality risk:

  1. What is the risk of recurrence of arterial dissection in an individual with a previous history of extracranial vertebral artery dissection?
  2. What is the long term mortality risk involved in an individual with vertebral artery dissection? [numbered]

vertebral artery dissectionFirst, let’s briefly review a few facts about extra-cranial vertebral artery dissection. Arterial dissection is a tear between the layers of the inside wall of an artery.

A false lumen can develop as blood accumulates in the small pouch within the artery. This may lead to a stroke from the development of a thrombus and emboli from the thrombus traveling to and blocking small vessels in the brain. Alternatively, a thrombus may totally occlude the vessel, resulting in decreased blood flow and an ischemic stroke. Or, if the dissection ruptures through the blood vessel, bleeding into the brain (subarachnoid hemorrhage) may result in a cerebrovascular accident.

Possible causes of arterial dissection include a hereditary predisposition, which can involve a connective tissue disorder (e.g., Ehlers-Danlos syndrome type IV and Marfan syndrome) or vascular conditions (fibromuscular dysplasia). However, this is a relatively rare cause for the condition (probably less than two percent caused by Ehlers-Danlos syndrome, for instance).

Figure 2 lists many of the connective tissue and vascular disorders associated with dissection.

Figure 2 - Conditions Associated with Dissection
Ehlers-Danlos syndrome type IV Autosomal dominant polycystic kidney disease
Fibromuscular dysplasia Osteogenesis imperfect
Cystic medical necrosis Homocystinuria 
Marfan syndrome Alpha-1 antitrypsin deficiency

Dissection may present due to hereditary disposition, connective tissue disorders

and vascular conditions, but more commonly dissection is caused by physical trauma, including coughing or sneezing episodes


More commonly the dissection will follow physical trauma with forceful neck movements, such as basketball, swimming, scuba diving, skating, roller coaster rides, automobile accidents or even coughing or sneezing. Population controlled studies have shown an association between chiropractor neck manipulation and vertebral artery dissections. Hair washing at beauty parlors, recent infections as well as elevated homocysteine levels also have been postulated to play a role.

Arterial dissection can occur in the carotid artery as well as the vertebral artery. One study showed the incidence of spontaneous internal carotid artery dissection to be 1.72 per 100,000 individuals compared to vertebral artery dissection of 0.97 per 100,000 individuals. Most authorities evaluate and treat internal carotid artery dissection similarly to vertebral artery dissection, classifying them as either extra-cranial artery or intracranial artery dissection. The CADISP study involving 982 patients generated interesting results (Figure 3).

Figure 3 - Characteristics Associated with Dissection
Characteristic Vertebral Dissection Internal Carotid Dissection
Bilateral dissection 16% 10%
Associated with minor trauma 37% 29%
Neck pain at presentation 66% 39%
Associated with recent infection 15% 22%
Mean age 41% 46
Transient monocular blindness 0 8%
HA at presentation 65% 68%

Neck pain and HA are most closely associated with dissection, according to the CADISP study of 982 patients.

 

Regardless of the etiology, vertebral artery dissection and carotid artery dissection account for up to 20% of cases of stroke in young adults. Dissection most often results in an ischemic stroke or transient ischemic stroke. Some 60-90% of cases have a symptom of head and/or neck pain. Up to 20% will have sudden and severe onset of this pain. Other symptoms include tinnitus, vertigo, orbital pain or cervical nerve root complications. 

Diagnosis & Treatment

Diagnosis is typically made by neuroimaging. An angiogram, MRA or CTA are common diagnostic procedures which will help establish the diagnosis. The MRA and CTA are frequently done to avoid the more invasive angiogram. The sensitivity and specificity of the MRA is similar to the CTA. Lumbar puncture is frequently done if there is concern about the presence of an associated subarachnoid hemorrhage.

Treatment typically includes antithrombotic therapy with either anticoagulation or antiplatelet medications. Some clinicians prefer anticoagulation for small or moderate sized infarction in the setting of an extra-cranial dissection, and antiplatelet therapy for larger infarcts. The presence of a subarachnoid hemorrhage generally discourages the use of anticoagulation however. Some clinicians prefer antiplatelet therapy for those with dissection and non-ischemic symptoms.

Unfortunately there is a paucity of controlled studies directly comparing treatment modalities, combinations of treatments and length of treatments. Guidelines issued by the American Heart Association/American Stroke Association (AHA/ASA) in 2011 do suggest antithrombotic therapy for at least three to six months as reasonable. The 2012 American College of Chest Physicians (ACCP) guidelines suggest using the general recommendations for patients with non-cardioembolic stroke, which typically involves aspirin initially and antiplatelet therapy (e.g., aspirin, clopidogrel, or cilostazol) for secondary prevention. The 2011 ASA/ASA guidelines suggest considering endovascular therapy with stenting for those who fail adequate antithrombotic therapy and consider surgery for those who fail stenting.

Prognosis
The prognosis for vertebral artery dissection, as is true generally for other types of strokes, is related to the severity of the associated ischemic stroke and/or subarachnoid hemorrhage. Better outcomes are associated with lesser initial stroke severity and those cases which show recanalization.

One study published in Stroke in 2006 evaluated outcomes in 169 patients with spontaneous vertebral artery dissection (SVAD). Brain ischemia occurred in 131 patients (77%; ischemic stroke 67% TIA 10%). Six (4%) suffered subarachnoid hemorrhage. Two patients died (2%) at 3 months. Many feel that factors associated with poor functional outcome include a high NIHSS score at onset, arterial occlusion, and older age. Half of long-term survivors suffer from significant quality-of-life impairments. 

Recanalization results have varied by study and observed timeframe. One study reported complete recanalization of the vertebral artery at six months in 62% of the 61 patients with dissection. In another study, 51% of the 76 patients with cervical artery dissection had complete recanalization at nine months and another 20 percent had partial recanalization.

Recurrence of cervical artery dissection does occur at times but the literature is somewhat inconsistent in the magnitude of this risk. Retrospective studies have suggested an approximate risk of 1% annually. However, in the CADISP study mentioned earlier the recurrence rate at 3 months was 2%. The rate in other studies ranges from 0-13%.

In summary, patients that experience an extra-cranial dissection have excellent or complete short-term recovery in 70-85% of cases, death in approximately 5% of cases and disabling complications in 10-25% of cases. Mortality may be higher in those with intracranial dissection.

Long-term mortality data is lacking but current data suggest recurrence of ischemic stroke is in the 0-13% range. The presence of an underlying connective tissue disease, vascular disease or hereditary condition predisposing to this condition would increase the risk of recurrence. Documentation of adherence to follow-up evaluation and therapeutic recommendations, complete revascularization of the artery on repeat neuroimaging and the lack of residual neurological deficits would be favorable prognostic characteristics.

Returning to the Case
In this particular case, an underwriter assessing  future mortality risk should note several favorable factors. The history of a unilateral vertebral artery dissection without significant neurological deficit and with no evidence of recurrence is encouraging. Likewise, complete revascularization revealed in repeat imaging of the artery is promising. Finally, there is documentation that there are no findings of any underlying condition which would make recurrence more probable.

The respiratory infection and the neck manipulation preceding the dissection may indicate a traumatic cause. He is actively trying to mitigate risk of future events. Seven years have passed without recurrence. There appears to be minimal risk of recurrent dissection in this particular case.

References

Arauz A, et al. “Recanalization of vertebral artery dissection.” Stroke. 2010; 41(4):717. 

Arnold, Marcel, et al. “Vertebral Artery Dissection: Presenting Findings and Predictors of Outcome.” Stroke. 2006; 37:2499-2503.

Biller, Jose, et al. “Cervical Arterial Dissections and Association With Cervical Manipulative Therapy.” Stroke. Published online 8-7-2014.

Furie, KL, et al. “Guidelines for the prevention of stroke in patients with stroke or transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association.” Stroke. 2011; 42(1):227.

Lansberg MG, et al. “Antithrombotic and thrombolytic therapy for ischemic stroke:  Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Guidelines.” Chest. 2012;141(2 Supplement).

Park, Kwan-Woong, et al. “Vertebral Artery Dissection: Natural History, Clinical Features and Therapeutic Considerations.” J Korean Neurosurgery Society. 2008. 44:109-115.

Rainer, D, et al. “Cervical artery dissection-clinical features, risk factors, therapy and outcome in 126 patients.” Journal of Neurology. Oct 2003; 250: issue #10 PP1179-1184. ∞