Abstract
A case of carotid artery dissection in a 41-year-old-woman is described whose main symptom was cluster-like pain. The case is interesting for its atypical presentation with only two other like cases in the literature, and the site of dissection, localized in the intrapetrous curvature of the carotid artery. The case highlights the need for active co-operation between clinician and neuroradiologist during neuroimaging assessment which must be focused on the clinical evaluation of the individual patient so as to avoid error, particularly in atypical cases.
Introduction
Arterial dissection is a condition in which, following laceration of the vessel wall, blood penetrates into the endothelium layers of the vessel, separating them and bringing about an occlusion of the lumen or an aneurismal dilation. Underlying aetiology is little known: at times a recent neck injury, even slight, can be identified which may be a causative factor; other times there would seem to be no identifiable cause and so the dissection is considered spontaneous. The role of neck trauma in provoking dissection of the neck arteries is not totally clear, whereas apparently spontaneous arterial dissection would appear to be connected to congenital structural alterations in the vessel wall. Chirotherapy of the neck and fibromuscular dysplasia must be listed among common causes of carotid artery dissection (1).
When the process involves the carotid or vertebral arteries, the resulting reduction in blood supplied to the brain or the possible formation of embolus are responsible for transient or permanent focal neurological symptoms. Carotid or vertebral artery dissection is included in group six of the International Headache Society (IHS) classification (2), ‘Headache associated with vascular disorders’. With the introduction in diagnostic practice of evermore sophisticated and fairly readily available investigations, carotid or vertebral artery dissection, once considered a rare cause of cerebrovascular disease and often revealed only at autopsy, has been proved to be responsible for stroke, in particular in young patients, in an increasing number of cases.
The annual incidence of spontaneous carotid artery dissection is around 2.5 and 3 per 100 000 (3, 4); the dissection of the vertebral arteries seems to be less frequent, with an annual incidence of between 0.5 and 2.5 new cases per 100 000 per year (5). Carotid or vertebral artery dissection can occur at any age but is most common in adults and is estimated to be responsible for around 20% of strokes in those under 40 (6).
Case
A 41-year-old woman was recently referred to us, complaining of the sudden appearance one month before our observation of severe pain localized at the corner of the left jaw, irradiating into the areas of the two upper branches of the fifth cranial nerve homolaterally, and lasting about six hours. During the attack she also complained of a modest compression headache in the left frontal-parietal region and at the vertex with photophobia; no nausea, vomiting or phonophobia was reported. Moreover, she experienced persistent slight pain in the left hemipharynx during swallowing and evident ptosis in the left eye. The following day, the stabbing pain at the corner of the jaw receded, leaving a modest diffuse compression headache, a barely noticeable eyelid ptosis and slight pain during swallowing on the left side. A direct MR brain scan was done elsewhere and found to be normal; oculistic and ORL examinations resulted normal but for ptosis. After about 20 days, during which residual symptoms remained unchanged despite treatment with analgesics, the patient complained of severe painful episodes of a pressing-throbbing quality, localized in the left retro-orbital region associated with a more evident eyelid ptosis and conjunctival injection in the left eye. The attacks occurred at regular intervals of two days, with onset at about 10 in the morning and lasted on average 4–6 h. Treatment with analgesics was ineffective. Ten days from the appearance of these new symptoms, the patient came under our observation. Familiar and personal history were unremarkable but for the appearance of an itchy skin eruption in the left neck region, following a probable insect bite the day before the beginning of the symptoms. More specifically, the patient did not complain of headache in the past, nor have any vascular risk factor. The patient denied experiencing any recent trauma, strain or manipulations of the neck. General examination was negative and ruled out the existence of Marfan's syndrome. Neurological examination revealed only a slight ptosis in the left eye. An ecoDoppler on the supra aortic and intracranial vessels, performed to exclude a possible carotid artery dissection, was normal. The previous direct MRI of the brain was re-evaluated together with a neuroradiologist and, on the clinical discussion, the presence of a slight hyperintense semilunar shape at the beginning of the intracranial part (petrous portion) of the internal left carotid artery, appearing only in a single T1 axial section, was in evidence, raising the suspicion of carotid dissection.
A MRI performed with fat suppression technique clearly confirmed the hypothesis of carotid dissection (Fig. 1).
T1-weighted axial section, at the carotid canal level. Fat suppression technique reduces the adipose tissue signal, which becomes slightly hypointense while the methaemoglobin subintimal blood maintains its hyperlucency signal. A mural haematoma is evident with consequent narrowing of the vessel lumen.
The patient was put on steroid and intravenous anticoagulant therapy with heparin. An isolated further episode of headache with the above-mentioned characteristics was experienced one day later. A control MRI, carried out more than two months after the onset of the first symptoms, showed reabsorption of the intramural haematoma. The patient did not complain of any other painful episodes (1 years follow-up).
Discussion
Carotid artery dissection is an event which in most cases presents itself with headache or pain along the vessel involved, Horner's syndrome and cerebral or retinal ischaemia variously associated. Headache is present in 60–80% of cases (7), is ipsilateral to the artery involved in around 2/3 of patients, represents the onset symptom in more than half the cases, and in a minority (around 4%) may remain as the only symptom (8, 9). Although headache is generally aspecific, in some patients it may appear with features similar to primary forms, and in particular to migraine (10–12): 22 patients of a series of 65 with nontraumatic carotid artery dissection suffered from migraine and in 6 of these the onset symptom was a headache with characteristics similar to those of previous attacks (8). Onset of pain is gradual, even though in some cases it may be sudden and violent suggesting subarachnoid haemorrhage (1–7), indeed, ‘thunderclap headache’ has been described in about 10% of a series of 135 patients with spontaneous carotid artery dissection, bringing up problems of differential diagnosis with subarachnoid haemorrhage (9).
Among the symptoms which may appear in carotid artery dissection, headache is generally the earliest even if the absence of pain symptoms does not exclude the diagnosis. Horner's syndrome, present in about half the cases, may accompany the headache or appear in isolation and should be taken as suspect. In 12% of patients the cranial nerves are affected, more often the hypoglossal. The percentage of patients presenting symptoms ascribable to retinal or cerebral ischaemia is variable (50–95%), and has fallen over the years, perhaps in relation to the chance of a more rapid diagnosis in patients with few symptoms (1).
Where clinical onset is limited to Horner's syndrome associated with pain in the frontal-orbital region, which occurred in 10% of the cases in Silbert et al. (9), the suspicion of a carotid artery dissection is not immediate.
The case reported is interesting for its clinical presentation and dissection site. The suspicion of an underlying secondary origin, justified by the sudden onset and almost simultaneous appearance of two types of headaches, was backed up by the constant presence of a partial Horner's syndrome; but the diagnosis was made more difficult because of the unusual intrapetrosal location of the dissection.
Indeed, Doppler sonography, a readily available examination, is highly sensitive for dissections involving the extracranial carotid artery but is of no value in the evaluation of the carotid intrapetrosal portion. In the suspect of carotid artery dissection, the elective investigation is at present MR scanning of the neck in thin sections with fat subtraction, which makes it possible to have a patognomonic image of a semilunar shape in the arterial wall confirming dissection.
In our case, notwithstanding the presumed negative findings of direct brain MRI and of the ultrasound study, the advisability of proceeding with further neuroimaging investigations was dictated by the positive findings at neurological examination, by the atypical characteristics of the cluster-like headache and by a careful reevaluation of the MRI already performed: our case stresses the importance that a request for neuroimaging should be focused according to the clinical suspicion and discussed with the neuroradiologist to allow the best accuracy in detecting details which may otherwise go unnoticed.
Whereas carotid artery dissection has been described presenting with a migraine type headache, in particular in patients with a history of migraine, besides a single case of cluster-like headache due to vertebral artery dissection (13), only two cases of carotid artery dissection with cluster-like features are documented (14, 15). In both cases, neurological examination identified a Horner's syndrome persistent between attacks.
Moreover, most carotid artery dissections involve the extracranial part of the carotid artery, whereas rarely have cases been described in which the vessel was interested in its intrapetrous portion (16); to our knowledge, this is the first report of a carotid artery dissection with cluster-like features and intrapetrous location.