A case series of partial Horner’s syndrome due to internal carotid artery dissection: More common than previously thought.

I Wallace, D Lockington and MO. McCarron

Departments of Internal Medicine (IW), Ophthalmology (DL) and Neurology (MOM).
Altnagelvin Area Hospital, Glenshane Road, Londonderry, Co. Londonderry, Northern Ireland, UK. BT47 6SB.

Correspondence: Dr Ian Wallace,
Regional Centre for Endocrinology and Diabetes,
Royal Victoria Hospital,
Grosvenor Road,
Belfast.
BT12 6BA
UK
Tel: 028 9063 4462
Fax: 028 9031 0111
E-mail: i.wallace@qub.ac.uk

We report a series of patients, who presented to a district general hospital with painful partial Horner’s Syndrome due to internal carotid artery dissection. None of the patients had a cerebral ischaemic complication and all were treated with aspirin. Internal carotid artery dissection is an important cause of headache and isolated partial Horner’s Syndrome. We highlight that internal carotid artery dissection may present with subtle symptoms and signs and suggest that emergency, acute and general physicians need to have a low index of suspicion for this condition. We suggest that internal carotid artery dissection may be a more common event than previously thought due to improved imaging techniques. We describe ongoing efforts to answer the question whether anti-coagulation or anti-platelet therapy is the most appropriate treatment.

Key Words
Horner’s syndrome
Internal Carotid Artery Dissection

 

Introduction
Internal carotid artery dissection (ICAD) may present with a painful partial Horner’s syndrome. Increasing availability of magnetic resonance imaging (MRI) may help identify such patients more frequently and alert clinicians to the risk of stroke. We report a consecutive series of four patients with ICAD in our district general hospital (DGH).

Case 1
A 43 year-old man had a right retro-orbital headache following a transatlantic flight. Seven days later his wife noticed that his right pupil was smaller than his left pupil. He denied any trauma or visual symptoms. Examination revealed a mild miosis and partial ptosis of his right eye. There was no enophthalmos and no sweating deficit. An MRI of brain demonstrated increased signal in the right internal carotid artery, consistent with extracranial dissection. There was no evidence of ischaemia. A contrast enhanced MR angiogram (CEMRA) showed a patent right internal carotid artery (ICA).

Case 2
A 44 year old man woke with a frontal headache. Later that day he developed a right temporal headache and noticed both drooping of his right eyelid and a smaller right pupil. He had a partial right Horner’s syndrome without anhidrosis (figure 1A). MRI of brain and CEMRA confirmed an extracranial ICAD (figure 1B and 1C).

Figure 1
(A) Partial right Horner’s syndrome in patient 2 showing right miosis and ptosis. (B) High signal in wall of internal carotid artery (arrow) on T1-axial MRI brain scan consistent with mural thrombus. This is sometimes referred to as the “crescent” or the “owl’s eye” sign. (C) CEMRA showing an irregular and stenosed (arrow) right internal carotid artery.

 

Case 3
A 41 year-old woman woke up with a severe pain along the right side of her face and scalp. Three days later she noticed that her right pupil was slightly smaller than the left. She was referred to hospital. She denied trauma, recent infection or visual problems. She smoked 10 cigarettes per day. She was on no medication. On examination she had a mild miosis and partial ptosis of the right eye. There was no evidence of anhidrosis. An MRI of brain and CEMRA confirmed a dissection of the right ICA.

Case 4
A 44 year old man had flu-like symptoms and a pain around his right ear for three weeks. He then noticed a right droopy eyelid, a small right pupil and infraorbital pain. Examination confirmed a partial right Horner’s syndrome without anhidrosis. MRI brain scan confirmed dissection of his right extracranial ICA.

All four patients were treated with aspirin. None has developed any evidence of stroke during follow up from 10 to 24 months.

Discussion
This series of consecutive patients with extracranial ICAD presented to a DGH with partial Horner’s syndrome (ptosis, miosis, absent anhidrosis) but without cerebral ischaemia. ICADs may cause headache or neck pain, a partial Horner’s syndrome and intracranial ischaemic events. This classical triad is found in less than one-third of patients, but the presence of two of these features is highly suggestive of an ICAD.[1] Headache occurs in two-thirds of patients with ICAD. The headache is usually frontotemporal, but can affect different locations ipsilateral to the dissection.[1] Annual incidence of spontaneous ICAD is estimated at 2.5 – 3.0 per 100,000 with incidence peaking in the fifth decade.[1,2]

All four patients had a right painful, partial Horner’s syndrome due to injury of the third order neurone. Third order neurones travel from the superior cervical ganglion along the ICA to innervate the radial (dilator) muscle of the iris and Mueller’s muscle of the eyelid. Fibres responsible for sweating over the face travel along the external carotid artery, explaining the absence of anhidrosis in our patients.

Diagnosis relies on a high clinical suspicion and the use of radiological imaging. Conventional angiography is invasive, not routinely available and carries a risk of stroke (0.5% - 1%). Non-invasive techniques include ultrasound, Computed Tomography (CT) angiography and MR angiography.[3] Ultrasound is limited by the inability to visualise the entirety of the internal carotid artery and is less sensitive than other techniques with nearly one third of patients with ICAD presenting with Horner’s syndrome having normal ultrasound findings.[4] CT and MRI are becoming routinely available and both have good sensitivity in the detection of dissections. CT may be limited due to the use of iodinated contrast and radiation. MR angiography and axial MRI is the more commonly performed investigation.

ICADs account for 10% - 25% of strokes in patients aged under 50 years. There is evidence that ischaemic events from ICAD are less frequent in the presence of a partial Horner’s syndrome compared to ICAD in the absence of a partial Horner’s syndrome.[5] This may reflect a more peripheral location of the intramural haematoma in the subadventitia with relative preservation of the lumen of the internal carotid artery.[5] However, a partial Horner’s syndrome does not totally preclude ischaemic brain injury.[5]

Intra-cranial ischaemic events from ICAD may occur by two mechanisms. The irregular carotid vessel wall can act as a site for thrombus formation and subsequent emboli may dislodge. Thrombo-embolic events account for greater than 90% of ischaemic episodes in ICADs. Haemodynamic compromise due to an expanding intramural haematoma may less frequently cause carotid occlusion and stroke.[1]

Treatment aims to reduce the risks of cerebral ischaemic events. It is not known whether anti-coagulation is better than anti-platelet therapy. Currently some authors suggest anti-coagulation rather than anti-platelet therapy when imaging illustrates vessel wall abnormalities, as these may act as a focus for thrombo-embolism. A randomised controlled multi-centre trial comparing anti-platelet and anti-coagulant therapy is required.[6] One such study in the United Kingdom, known as the Cervical Artery Dissection in Stroke Study (CADISS) is currently at the feasibility stage.

An evidence base to guide follow-up is lacking. It is not unusual to repeat neuroimaging at 3 months to exclude a false aneurysm or document recanalisation. Some clinicians advocate discontinuing treatment at this stage if the vessel lumen has returned to normal.[1]

Conclusion
Our case series of four patients presented with subtle clinical signs due to a potentially life-threatening and debilitating aetiology. We suggest that increased availability of MRI scanners in many DGHs may lead to increasing recognition of ICAD as a cause of Horner’s syndrome. Subgroup analyses in CADISS of patients with partial Horner’s syndrome will be required to determine future evidence-based treatment.

References

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  3. Johnston DCC, Chapman KM, Goldstein LB. Low rate of complications of cerebral angiography in routine clinical practice. Neurology. 2001; 56: 1009-1015.
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