Some authors have advocated aggressive surgical

management to prevent involvement of distal branches of the

internal carotid artery when completed stroke has not yet

occurred. http://www.ajnr.org/content/11/6/1150.full.pdf

warfarin,asa,clopidogrel have been used to prevent stroke,Surgical intervention for carotid dissection is reserved for patients with recurrent TIAs or progressive neurological deficits secondary to hypoperfusion or embolic phenomenon despite maximal medical therapy.  endovascular stenting could be even better than open surgery if the initial treatment of choice once medical therapy fails in adults . If there are recurrent TIAS or inminent stroke an extracranial to intracraneal  bypass procedure could be performed by a vascular neurosurgical team 

Most ICAD will heal spontaneously, and therefore more conservative approaches are usually indicated in the absence of persistent ischemia. Conservative treatment with anticoagulation to prevent further thrombus formation and to promote internal thrombotic fibrinolysis and subsequent healing is most favored. Anticoagulation is continued with periodic monitoring of the dissection via Doppler ultrasonography until healing is achieved, generally for several months. For patients in whom anticoagulation is contraindicated because of bleeding risks, antiplatelet therapy is appropriate.

Hostettler C.Traumatic carotid artery dissection.Mil Med. 2013 Jan;178(1):e141-5. doi: 10.7205/MILMED-D-12-00133.

but the question was INTRACRANIAL EXTENSION:

the outcome is CATASTROPHIC + The most common site of intracranial dissection is the

supraclinoid internal carotid artery.  SAYS THIS ARTICLE:

'Supraclinoid Carotid Artery Dissection Following Unusual

Trauma Richard M. O'Sullivan,1.2 William D. Robertson, 1 Robert A. Nugent, 1 Kenneth Berry,3 and lan M. Turnbull4 '

There is indeed no consensus, but there is emerging agreement that LMWH followed by aspirin is appropriate for the non-stroked, while either stent-reperfusion or embolization to prevent TIA's is the option for the one's already stroked. Stents may be the best option for the larger lesion (AIS Grades 3-4), while surgery is appropriate for Grade 5 with no neurology.