very interesting case of of Internal carotid artery dissection from Medscape...
A 57-year-old man presents to the emergency department with left-sided facial, arm, and leg weakness along with slurred speech after suffering violent and repetitive bouts of coughing. His wife has the impression that his right eye is smaller than the left. The patient also complains of pain over his right eye. His medical history is notable for hypertension and smoking 1 pack of cigarettes per day for 10 years. He denies any illicit drug use. He does not consume alcohol. He is employed, does not exercise, and has a sedentary lifestyle. There is no history of previous head or neck injury.
On physical examination, his oral temperature is 97.3°F (36.3°C). His pulse is regular with a rate of 94 bpm. His blood pressure is 195/105 mm Hg. The examination of his head and neck is normal. His lungs are clear to auscultation and have normal respiratory effort. No cardiac murmurs are detected. His abdomen is soft and nontender, with normal bowel sounds on auscultation. On neurologic examination, the patient is alert and oriented to time and place. His speech is slurred and dysarthric. On cranial nerve examination, the right pupil constricts from 2 mm to 1.5 mm in response to light, whereas the left pupil constricts from 3 mm to 2 mm. The right eyelid has 3 mm of ptosis compared with the left eye, and the right eye appears to be smaller than the left one. Pupillary asymmetry is more apparent when lights in the room are dimmed. Funduscopic examination reveals normal fundi. Visual acuity is normal bilaterally. The extraocular movements are intact. Facial sensation is decreased to light touch and pinprick on the left side. The patient has a decreased left nasolabial fold. He has weak movements of the left side of the face, without forehead involvement. The gag reflex is present, and there is normal palate elevation. After pinching the left side of the neck, the left pupil dilates normally (ciliospinal reflex). After pinching the right side of the neck, the right pupil does not dilate. He is unable to stand and walk. Muscular tone is flaccid on the left side but normal on the right. He has a marked left hemiparesis. The patient's reflexes are normal throughout except for an up-going plantar response on the left side, compared with a down-going one on the right. The patient reports decreased sensation to light touch, temperature, pinprick, joint position, and vibration on the left half of the body. His National Institute of Health Stroke Scale (NIHSS) is 11.
Routine laboratory analyses are performed and result normal. Chest x-ray is normal. ECG shows left ventricular hypertrophy. A noncontrast CT scan of the head reveals a hyperdense right middle cerebral artery (Figure 1).
Conventional angiography reveals stenosis at the origin of right internal carotid artery, with an abrupt narrowing of its lumen ("rattail-filling defect"; Figure 2).
he patient in this case presented with a pattern of sensory loss and weakness on the left side of his body consistent with a lesion involving the right corticospinal and corticobulbar fibers and the primary somatosensory cortex. The most likely diagnosis was an ischemic stroke. Neurologic examination also revealed ptosis of the right eye with narrowing of the palpebral aperture, miosis in the right eye with a pupil that was reactive to light, and reduced ciliospinal reflex on pinching the right side of the neck. These signs are consistent with a partial Horner syndrome resulting from injury to sympathetic fibers traveling with the internal carotid artery. The sudden onset of neurologic deficits after violent coughing and the presence of pain over the patient's right eye are highly suggestive of a right internal carotid artery dissection. Conventional angiography was performed because the clinical findings were highly suspicious for an internal carotid artery dissection; this confirmed the diagnosis by showing an abrupt narrowing of the vessel's lumen ("rattail-filling defect"). The hyperdense middle cerebral artery revealed by noncontrast CT scan of the head suggested an occlusion of this artery. Laboratory analysis performed during hospitalization revealed the presence of mild hyperlipidemia. Screening analyses for hypercoagulability and rheumatologic disorders were normal. Transthoracic echocardiography was normal; however, duplex ultrasonographic imaging showed a stenosis in the right internal carotid artery.
Dissection of the internal carotid artery is an important cause of cerebrovascular disease in young adults. One study out of Rochester, Minnesota, showed an annual incidence of 2.6 patients out of 100,000 population. The actual incidence is difficult to evaluate, however, and may be higher because this condition, which may be asymptomatic or have various clinical presentations, may go unrecognized.[1] The incidence appears to have increased since the 1980s, but is likely due to the availability of better imaging studies.[1]
Dissection normally occurs in the extracranial segment of the epiaortic vessels. The internal carotid artery is affected more often than the vertebral artery.[2] Dissections can be classified as traumatic or spontaneous. Traumatic dissections are linked to direct neck trauma or injury, whereas spontaneous dissections may be secondary to predisposing factors, such as fibromuscular dysplasia, Ehlers-Danlos syndrome, cystic medial necrosis, or Marfan syndrome. These conditions cause an abnormal, weakened arterial wall, thus predisposing patients to arterial dissection.[3]
Internal carotid artery dissection develops as a consequence of a tear in the intimal layer of the vessel, which allows blood to enter the wall of the artery and to split its layers, which is termed a subintimal hematoma. This means that the hematoma is located between the intimal and medial layers of the artery. Alternatively, a rupture of the vasa vasorum causes a subadventitial hematoma (ie, a hematoma between the media and the adventitial layers). Internal carotid artery dissection can lead to thrombus formation and the risk for distal embolization, whereas arterial narrowing with stroke due to inadequate blood flow is a less common mechanism of ischemia.[4]Hematoma formation and a localized inflammatory response result in compression of nearby structures, such as the sympathetic fibers of the superior cervical ganglion, which lies in the posterior wall of the carotid sheath. This can cause a postganglionic oculosympathetic palsy. There is no anhidrosis because sweat fibers run with the uninvolved external carotid artery.
The most typical signs and symptoms of internal carotid artery dissection are neck pain and/or a partial Horner syndrome. This may be followed by an ischemic event ipsilateral to the ocular signs, with somatosensory and/or motor deficits contralateral to ocular signs as a consequence of distal embolization to the intracerebral arteries.
A highly suggestive constellation of signs and symptoms frequently seen with internal carotid artery dissection is Horner syndrome. Oculosympathetic palsy in the form of Horner syndrome has long been recognized as a typical manifestation of internal carotid artery dissection, although it is found in fewer than half of patients. The classic signs of Horner syndrome are ptosis of the upper lid, slight elevation of the lower lid (upside-down ptosis), and miosis reactive to light. The narrow palpebral aperture secondary to upper-lid ptosis and elevation of the lower lid give the illusion that the affected eye is smaller than the contralateral eye (illusory enophthalmos). Horner syndrome is an expression of a disruption of oculosympathetic pathways. Ptosis (ie, upper eyelid droop) is caused by a loss of innervation to Müller's smooth muscle in the upper lid. This small muscle is innervated by sympathetic fibers and is responsible for eye opening, together with the superior and levator palpebrae: striated skeletal muscle innervated by the third cranial nerve. Similarly, miosis (ie, decreased papillary size) is caused by a loss of sympathetic innervation to the iris pupillodilator muscle. As a consequence, the pupil cannot dilate. This impaired dilation of the pupil may also be observed in a test of the ciliospinal reflex. Normally, pinching the neck causes a papillary dilation secondary to the activation of sympathetic pathway. In an eye with Horner syndrome, this dilation does not occur.
Currently, the most commonly available imaging modalities are carotid ultrasonography and CT angiography (CTA) of the head and neck. However, the best method to diagnose an internal carotid artery dissection is a combination of CTA and magnetic resonance angiography (MRA) with fat-suppressed T1 images.[1,5,6] CTA and MRA are replacing conventional angiography in the diagnosis of internal carotid and vertebral artery dissection because the resolution and accuracy of CTA and MRA are similar to that of angiography.[7-9] Moreover, MRI may show the intramural hematoma itself. As an alternative, conventional angiography with digital subtraction may be used, although these tests are more expensive and invasive than MRI/MRA. Additionally, MRI/MRA is superior to conventional angiography in diagnosing dissections without associated luminal abnormalities.[1] Conventional angiography may reveal an abrupt narrowing of the internal carotid artery lumen (rattail-filling defect or the "string sign"). Carotid duplex ultrasonographic imaging may also be useful, especially in the younger population, with less chance of severe atherosclerotic disease, which can interfere in the diagnosis.[10] Direct observation of a luminal intimal flap is diagnostic but rare; the most frequent finding is a stenosed or occluded vessel in the absence of atheromatous lesions.[11,12]
The treatment of internal carotid artery dissection consists of anticoagulation with intravenous heparin followed by oral anticoagulation for 3-6 months.[13] However, there are no randomized controlled trials supporting such a therapeutic approach, and the validity of such treatment has never been definitively proven.
The patient in this case was first treated with intravenous heparin followed by oral anticoagulation in order to prevent distal embolization. He continued anticoagulant therapy for 3 months. The patient's Horner syndrome resolved completely after 3 days, but the left-sided sensorimotor deficits persisted at discharge.
