Carotid artery dissection is a separation of the layers of the artery wall supplying oxygen-bearing blood to the head and brain and is the most common cause of stroke in young adults. (Dissection is a blister-like de-lamination between the outer and inner walls of a blood vessel, generally originating with a partial leak in the inner lining. )Dissection may occur after physical trauma to the neck, such as a blunt injury (e.g. traffic collision), strangulation, but may also happen spontaneously. Signs and symptoms
The signs and symptoms of carotid artery dissection may be divided into ischemic and non-ischemic categories:Non-ischemic signs and symptoms:

Localised headache, particularly around one of the eyes
Neck pain
Swollen tongue
Decreased pupil size with drooping of the upper eyelid (Horner syndrome)
Pulsatile tinnitusIschemic signs and symptoms:

Temporary vision loss
Ischemic stroke

Causes
The causes of internal carotid artery dissection can be broadly categorized into two classes: spontaneous or traumatic.
Angiotensin II (Ang II) is a medication that is used to treat hypotension resulting from septic shock or other distributive shock. It is a synthetic vasoconstrictor peptide that is identical to human hormone angiotensin II  and is marketed under the brand name Giapreza. The Food and Drug Administration approved the use of angiotensin II in December 2017 to treat low blood pressure resulting from septic shock.The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication. Medical uses
Angiotensin II is a vasoconstrictor used to increase blood pressure in adults with septic or other distributive shock. Angiotensin II is a naturally occurring hormone secreted as part of the renin-angiotensin system that results in powerful systemic vasoconstriction. The vasopressor effects of angiotensin have been studied since it was first isolated in the late 1930s. Vasopressors are defined as agents that combat vasodilatory shock by inducing peripheral vasoconstriction. Commonly used vasopressors include catecholamine (e.g., dopamine, norepinephrine, epinephrine) and non-catecholamine (e.g., vasopressin). but these agents are not always effective in reversing vasodilatory shock, and their use can be associated with significant side effects including limb ischemia and cardiac arrhythmia. Angiotensin II is as a treatment option that can increase blood pressure and allow catecholamine dose reductions. Angiotensin II must be administered as an intravenous infusion diluted in 0.9% sodium chloride prior to use. The recommended starting dosage of angiotensin II is 20 nanograms (ng)/kg/min via continuous intravenous infusion. Administration through a central venous line is recommended.