Treatment of LS-TIA includes surgical revascularization and medical modalities, but most of the patients are still treated conservatively with medication1, 3. To date, aggressive medical treatment with antiplatelet agents, statins, and risk-factor modification remains the first choice for patients with LS-TIA. These patients may benefit from revascularization therapy beyond aggressive medical management alone. Surgical management can be considered if the patient remains refractory to medical therapy. In most cases, LS-TIA is predominantly caused by stenosis or occlusion of the ICA. Carotid endarterectomy is a good choice to relieve symptoms and reduce the risk of stroke. In our presented case, the key to the successful resolution of this case was to remove the CCA plaque in the long segment.
The incidence of CCAO is approximately 3% in patients who undergo angiography for symptomatic cerebrovascular disease4. To date, guidelines have not recommended an optimal surgical procedure for CCAO5, which remains controversial. Endovascular therapy and open surgery have been reported as means of treating CCAO, such as carotid stenting, carotid-carotid artery crossover bypass and extracranial-intracranial (EC-IC) bypass surgery. However, when performing CCA stenting, it is usually challenging to pass the guidewire through chronic long-segmental occluded lesions, and the risk of vascular dissection and cerebral infarction is high. Carotid-carotid artery crossover bypass is an option for the treatment of CCAO, but the extra-anatomical approach and infections of the synthetic vascular grafts are the problems association with this surgical procedure. The Carotid Occlusion Surgery Study (COSS) compared medical therapy to EC-IC bypass in patients with recently symptomatic carotid occlusion6. However, thirty-day rates for ipsilateral ischemic stroke in the surgical group were significantly higher than in the nonsurgical group (14.4% vs. 2.0%).
After a full pre-operative assessment, we performed RS-CEA for this patient instead of carotid-carotid artery crossover bypass or EC-IC bypass. The advantage of RS-CEA is that it can simultaneously treat long-segmental CCAO and initial-segmental occlusion of ICA with a relatively small neck incision. A retrospective study showed that RS-CEA was an effective treatment for chronic CCAO7. Although RS-CEA is effective in the treatment of CCAO, it may cause vascular rupture and restenosis. This technique requires a great deal of surgical training and sufficient endovascular skill. Our centre has performed RS-CEA on selected cases of long-segmental CCAO since 2008.
Although compromised hemodynamics secondary to an occlusive disease has been suggested as the cause of LS-TIA, the exact pathophysiology underlying limb-shaking is not clear. The pathophysiology of LS-TIA can be explained by the hypoperfusion theory. Tatemichi8 found significant hypoperfusion of the right dorsofrontal and upper rolandic regions contralateral to the shaking limb in a 63-year-old patient. In this case, we found hypoperfusion of the right corpus striatum. These reversible deficits in cerebral blood flow, which were maximal in the corpus striatum region, are consistent with low perfusion in the border zone territory. The physiological function of the striatum is to maintain the stability of movement. Involuntary movement, such as hand-foot tremor, can be caused by striatal dysfunction. This suggests that hemodynamic failure is the potential mechanism underlying LS-TIA secondary to CCAO. It is worth noting that the patient’s visual acuity and visual field increased after surgery. This may be explained by the improvement in the blood flow in the ophthalmic artery9.
In conclusion, our case sugests that hemodynamic failure is the potential mechanism underlying LS-TIA secondary to CCAO. The RS-CEA is an effective treatment for long-segment CCAO.