Lateral medullary syndrome, a posterior circulation stroke syndrome with a distinct set of clinical findings, is a recognized consequence of vertebral artery dissection. Cervical artery dissection (including vertebral artery dissection) is a documented complication of chiropractic cervical spinal manipulation. This report presents a case of a young female who presented with bilateral vertebral artery dissection post-chiropractic manipulation. The incidence and clinical outcomes of vertebral artery dissection, and the pathophysiology and clinical findings present in lateral medullary syndrome, will be discussed.

A 25-year-old female presented to the emergency department in October 2011 with occipital headache of four-week duration and new onset dizziness, paresthesia, dysphagia, and 'pulling to the left', which developed whilst jogging that morning. History revealed visits to a chiropractor with posterior headache and neck pain, four weeks and one week prior to this presentation. Cervical manipulation was performed on both occasions. Worsening left occipital and cervical pain developed following the second visit, with associated nausea and vomiting.

Neurological examination revealed an ataxic gait with falling to the left. Facial inspection revealed a left ptosis and miosis, consistent with partial left-sided Horner's syndrome. Nystagmus was present with rapid horizontal phase towards the right. Left-sided facial weakness and bulbar involvement was evident with a flattened left nasolabial fold, decreased left palatal movement, and uvula deviation to the right. Decreased pin-prick sensation and loss of temperature discrimination was detected over the left maxilla and throughout the right upper and lower limbs. Posterior columns were intact.

Left-sided cranial nerve signs, ipsilateral Horner's syndrome, and contralateral spinothalamic involvement suggested lateral medullary syndrome. A provisional diagnosis of a left medullary lesion secondary to vertebral artery dissection was made given the lack of typical stroke risk factors and the history of recent spinal manipulation. Differentials included embolic phenomena and tumor given the patient's age.

Magnetic resonance imaging (MRI) scan revealed a DWI-enhancing lesion in the left lateral medulla. (Figure 1) Subsequent magnetic resonance angiography (MRA) was suspicious for left vertebral artery dissection. A follow-up MRI scan at 4th-week post-incident revealed a new, asymptomatic, lesion in the right cerebellum. Repeat MRA (Figure 2A) and CTA (Figure 2B) of the vertebral arteries revealed bilateral vertebral artery dissection with bilateral posterior inferior cerebellar artery (PICA) territory infarcts. The patient was managed conservatively with aspirin and atorvastatin, progressing well with rehabilitation.

Lateral medullary syndrome (or Wallenberg syndrome) is a recognised complication of posterior circulation infarction, usually the result of ipsilateral vertebral artery or PICA occlusion. [1] Clinical features are related to vestibulocerebellar, sensory, bulbar and autonomic nuclei involvement. (Table 1) Spinothalamic tract involvement leads to impaired pain and temperature sensation over the contralateral side of the body (due to fiber decussation in the spinal cord), while Horner's syndrome (ipsilateral ptosis and miosis) is related to descending sympathetic tract impairment. [1]

Cervical artery dissection (internal carotid or vertebral artery dissection (VAD) has an annual incidence of 2.6-3.0 per 100,000 people. [2] It is the primary cause of 2% of ischemic strokes but accounts for 10–25% in young adults. [2]

There have been case reports associating chiropractic manipulation with unilateral and bilateral VAD and epidemiological links have been established. [3] [4] Spinal manipulation therapy is an independent risk factor for VAD and accelerates embolization in existing lesions. [4] The vertebral artery is particularly susceptible to cervical manipulation due to its mobility within the vertebral foramina, its proximity to the vertebral bodies, and its sharp directional change. [3]

The aim of early diagnosis and treatment of VAD is to prevent progression to ischemic stroke and other thrombotic complications. Currently, there are no published multi-cohort trials evaluating anti-coagulation versus anti-platelet agents for treatment of VAD. A recent meta-analysis for internal carotid artery dissection revealed no significant difference in outcome between anticoagulants and anti-platelets. [5] Prognosis is usually favorable for VAD, with low recurrence rates, good functional recovery and high rates of recanalization. [3]

Chiropractic spinal manipulation is a recognised cause of vertebral artery dissection (VAD) presenting symptoms may vary from ipsilateral occipital headache to signs of cerebral ischemia such as lateral medullary syndrome. Patients presenting with headache and focal neurology following spinal manipulation should be managed with a high index of suspicion.

Special thanks to Dr Jane Hoare (Specialist Physician and Director of Medicine - Ipswich Hospital), Dr Johannes Moolman (Cardiologist - Ipswich Hospital) and Dr Benjamin Ong (Diagnostic Radiologist - Princess Alexandra Hospital).

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