Identification of Internal Carotid Artery Dissection in Chiropractic Practice
Written by Editor   
Friday, April 17, 2015 12:00 AM

Internal carotid artery dissection (ICAD) is a condition wherein there is a separation of the artery’s intimal lining from its medial division, with subsequent extension of the dissection along varying distances of the artery, usually in the direction of blood flow. It has been suggested that ICAD produces stroke in 36–68% of patients as a result of occlusion of the artery at or near the site of the dissection, or embolization occurring distally from a dislodged fragment of thrombus.

ICAD is not a rare condition, with incidence estimates exceeding 7,000 cases per year in the United States. Accordingly, patients with this disorder may present to DCs for treatment of associated symptoms that often mimic musculoskeletal conditions. Established chiropractic patients may also develop ICAD coincidentally during their course of chiropractic management, with no relationship to manipulation. However, when ICAD is recognized, an urgent referral for a neurological and vascular evaluation is appropriate. This article summarizes the presentation, diagnosis, and proper management of patients with this potentially life-threatening condition.

The most common presenting symptoms of ICAD are headache and neck pain, which are typically severe and of sudden onset. There is wide variation in the location of pain, but most commonly it involves the ipsilateral periorbital, frontal, or upper cervical region.  

One series of 36 ICAD patients reported headache to be present in more than 90% of the cases, with focal cerebral ischemic symptoms in 67%. In a series comprising 135 ICAD cases, headaches were described by 65 patients as being unique, or of different character than what they had previously experienced, while 40 patients indicated that the headaches were familiar.

The second most common clinical manifestations are ischemic signs and symptoms, which include cortical transient ischemic attacks (TIA’s), stroke, or both, and less frequently, transient monocular blindness. Transient monocular loss of vision has been reported in from 6% to 30% of patients presenting with ICAD. Another common sign of ICAD is an incomplete Horner’s Syndrome.  The Horner’s Syndrome variant found in ICADs may be painful, and when of sudden onset is strongly suggestive of this condition.  

Most common presenting symptoms of ICAD (In descending order):

SymptomReported FrequencyCharacter
Headache and neck pain >90% Typically severe and of sudden onset, affecting the ispsilateral periorbital, fontal, or upper cervical region.
    Often unique, or of different character than previously experienced.
Ischemic symptoms 50–95% Transient ischemic attacks (TIAs) or stroke.
Horner’s Syndrome <52% Incomplete, lacking anhydrosis. May be painful.
Visual scintillations 33% Episodic
Monocular blindness 6–30% Transient
Subjective bruit 25–48% May also manifest as a pulsatile tinnitus.
Dysgeusia 10–19% Impairment of taste.


Greater than 10% of ICAD patients experience cranial nerve palsies that almost always involve cranial nerve XII, but IX, X, and XI have also been affected. The cranial nerve palsies are thought to be the result of disruption of their blood supply by way of mechanical compression from the distended ICA or by embolization.  

In general, clinical findings appear to be different when comparing traumatically induced ICAD to spontaneous ICAD. In the traumatic group, focal cerebral ischemic symptoms were the most common manifestations. In the spontaneous group, unilateral heaches were the most commonly experienced symptom, often in association with Horner’s Syndrome. Like spontaneous ICAD, the onset of ischemic signs and symptoms may be delayed in traumatic cases. The longer this delay, the greater the confusion in assigning any causation to the ICAD.

ICAD can be very difficult to diagnose, and is often overlooked, especially in its early stages before ischemic signs are apparent. It may go undiagnosed in cases that only cause mild symptoms or are asymptomatic. Asymptomatic ICAD has occasionally been detected incidentally, for instance during imaging of the opposite carotid or vertebral arteries for suspected dissection. This suggests that many cases are never discovered, and probably heal spontaneously.

No treatment protocol has been validated as being successful thus far. However, the traditional medical intervention in ICAD is anticoagulation therapy. Interestingly, up to one third of diagnosed spontaneous ICAD patients have received no treatment. Surgical intervention is not indicated in most cases, but is reserved for a small subset of patients who do not respond to anticoagulation. 

The outcome of ICAD is variable. Some patients recover completely, while others experience severe permanent deficits. A small percentage die as a result of complications associated with ICAD. DCs may encounter patients with this condition in their practices. When identified, the chiropractic management of ICAD patients involves immediate referral to an appropriate medical specialist. Unwarranted delay may result in progression of the ICAD even in the absence of any treatment. In addition to urgent referral, it is recommended that any identified ICAD patient not receive cervical manipulation, as a few case reports have correlated worsening of the condition with the intervention. Moreover, any form of excessive or abrupt cervical motion may dislodge an embolus.

Unfortunately, ICAD may be completely asymptomatic or symptoms may appear to be benign (e.g., headache, neck pain, or cervicogenic dizziness). Consequently, the condition may be nearly impossible to identify, at least in its early stage. There is currently no credible evidence to support the opinion that cervical manipulation causes ICAD. However, a close temporal relationship between the chiropractic manipulation and the onset of symptoms may give the appearance of a causative relationship. As a result, medical neurologists may report this to patients who develop ICAD subsequent to chiropractic manipulation. 

There are no pre-manipulation screening tests available that are capable of reliably identifying patients who are likely to develop cervical artery dissection. Realizing that ICAD is often difficult and sometimes impossible to diagnose, DCs should be aware of the information summarized and consider it in patients who are candidates for cervical manipulation, especially in cases involving new, severe, or unusual headache and/or neck pain. When ICAD is suspected, the patient should be immediately referred to an appropriate medical specialist for evaluation and possible treatment.