Unusual case of traumatic carotid artery dissection occurred during a work-related activity. A case report.

Carotid artery dissection secondary to cervical blunt trauma is a rare and potentially life-threatening condition that can cause a variety of clinical presentations, including stroke, headache, neck pain, tinnitus, Horner syndrome and cranial neuropathies and is associated with long-term sequelae. We report a case of a 49-year-old industrial vehicles mechanic who was projected to the ground by the explosion of the tire of a heavy truck he was inflating. In the following hours he presented various neurological signs and symptoms and was admitted to the Emergency Department. During hospitalization the patient underwent clinical and instrumental investigations with AngioCT and MR finding of left internal carotid artery dissection in correspondence of its cervical segment and three acute ischemic lesions in the left temporal, parietal and occipital lobes. Medical management was successful and the patient was discharged from the hospital three weeks after the admission but he wasn't able to get back to work due to neurological sequelae. This case report illustrates that traumatic carotid artery dissection, although rare, should be considered in patients who present neurological symptoms after an explosion, can meet the criteria for a work-related injury and may lead to a permanent decrease in the ability to work.

Introduction

Traumatic carotid artery dissection (CAD) is a rare and potentially life-threatening condition that occurs in approximately 1% of all patients with blunt injury mechanisms (6) and is an important cause of ischemic stroke among young adults, accounting for 25% of ischemic stroke cases in patients younger than 45 (1).

Trauma mechanisms involved range from high speed motor vehicle accidents to trivial traumas in predisposed patients (for example patients with hypertension or connective tissue diseases). Distraction/extension, distraction/flexion or lateral flexion forces of the cervical spine may result in traumatic CADs as well (5).

Other clinical presentations include headache, neck pain, tinnitus, Horner syndrome and cranial neuropathies (1, 4, 2), and timing of ischemic signs onset is very variable: only 10% of cases present immediate symptoms although most clinical signs usually occur within the first 24 hours of the occurrence of the trauma (5).

With medical treatment, regression of the dissection and disappearance of the mural haematoma is observed in over 80% of cases at radiological follow-up but neurological sequelae and various degrees of residual stenosis may occur (1).

Case report

A 49-year-old industrial vehicles mechanic was inflating the tire of a heavy truck with the help of a colleague when the tire exploded and the two men were projected to the ground. The precise dynamic of the accident was recorded by the video surveillance system of the garage (figure 1).

Figure 1

Screenshots captured from the video surveillance system recording of the garage. The circled man is directly hit by the explosion, with a resulting cervical hyperextension causing a left internal carotid artery dissection; his colleague falls to the ground, suffering minor injuries to a hand

The 49-year-old man immediately began to suffer from left tinnitus and oppressive headache that partially regressed with symptomatic therapy.

The following morning, while he was working, he presented aphasia, left eyelid twitch, tremors and uncontrolled movements of the left limbs and was initially admitted to the Emergency Department.

Neurological exam assessed a subjective mild hypoesthesia in the left trigeminal territory and the patient underwent laboratory tests and instrumental investigation.

Computed Tomography (CT) Angiography of the head and supra-aortic arteries showed a kinking of the left internal carotid artery and a contextual soft thickening of the vascular wall causing a 50% luminal stenosis in correspondence of its cervical segment. This finding was suggestive of an atheromatous plaque or a focal dissection, and Magnetic Resonance Imaging (MRI) was requested by the radiologist for the differential diagnosis.

MRI of head and soft tissues of the neck (figure 2) detected three acute ischemic lesions in the left temporal, parietal and occipital lobes, as well as a signal hyperintensity of the left internal carotid wall in correspondence of the kinking with luminal stenosis shown by the CT angiography due to methaemoglobin products that at first was assumed to be related to a mural hematoma or less probably to an intraplaque hemorrhage.

Figure 2

MRI of head and soft tissues of the neck performed the day after the traumatic event. The arrows show ischemic lesions in the left temporal (A), parietal (B) and occipital lobes (C) and a signal hyperintensity of the left internal carotid wall (D)

An echocolor Doppler study of the carotid artery was also performed but didn’t show any morphological changes consistent with a dissection in the examined segment of the vessel.

Therefore the man was diagnosed with arterial ischemic stroke in the middle cerebral artery vascular territory consequent to traumatic left internal carotid artery dissection without surgical indications and transferred to a Stroke Center.

Medical management was successful and the patient, who was judged clinically improved but with a complete inability to work, was discharged from the hospital three weeks after admission.

Five months after the accident MRI of the head and MR angiography of the supra-aortic arteries showed a better visualization of the flow-related signal in correspondence of the cervical segment of the left internal carotid artery, a marked vascular wall hyperintensity reduction in T1-weighted scans in correspondence of the kinking and the disappearance of the focal stenosis (figure 3).

Figure 3

MR angiography of the supra-aortic arteries (T-1 weighted scans) performed five months after the accident showing the disappearance of the focal stenosis and a marked hyperintensity reduction of the left internal carotid wall in correspondence of the kinking

The forensic medical examination performed six months after the work-related injury revealed the persistence of a significant bilateral contracture of the sternocleidomastoid muscle, more marked on the left, and an homolateral contracture of the trapezius, painful neck movements, neck rotation possible only with a contemporary torso rotation, left arm and leg strength deficit, slight uncertainty in coordination tests and asymmetrical squat test (greater loading of the right leg). The examinee also alleged hypoesthesia of the left hand (back of the carpus, first and fourth finger) and paresthesia of lower limbs refractory to medical treatments.

The biological damage caused by these disabling sequelae was judged equal to 15% and led to a permanent decrease in the ability to work. Work reintegration was possible only after appropriate retraining in a different employment field.

Conclusions

We reported a rare case of traumatic internal carotid artery dissection as a consequence of a truck tire explosion.

The site of injury, the production mechanism, the timing of ischemic signs onset and the evolution of clinical manifestations make the injury consistent with the explosion occurred while the mechanic was inflating the tire.

Moreover, the internal carotid artery dissection was caused by a violent and unexpected external event that occurred in the work environment while the employee was performing a work-related activity and led to a temporary complete inability to work for more than three days and to a permanent decrease in the ability to work and therefore it meets the requirements for being defined a work-related injury according to Italian law (3).

Due to the long-term sequelae, the man was no longer able to lift weights, use medium-heavy tools, perform works that require an extension of the cervical spine, drive industrial vehicles nor climb ladders, and since working as a mechanic requires manual handling of loads with lifting of the arms overhead and forced postures with neck hyperextension, these long-term sequelae caused also an important decrease in the specific ability to work estimated at approximately 40%.

Finally, this case report highlights the importance of appropriate retraining in a different employment field when the disabling sequelae of a traumatic event prevent the patient to return to his previous job.

No potential conflict of interest relevant to this article was reported by the authors