Others may experience unsteadiness or lack of coordination due to involvement of the cerebellum, and still others may develop visual loss (on one side of the visual field) due to involvement of the visual cortex in the occipital lobe. In the event of involvement of the sympathetic tracts in the brainstem, a partial Horners syndrome may develop; this is the combination of a drooping eyelid, constricted pupil, and an apparently sunken eye on one side of the face.If the dissection of the artery extends to the part of the artery that lies inside the skull, subarachnoid hemorrhage may occur (1% of cases). This arises due to rupture of the artery and accumulation of blood in the subarachnoid space. It may be characterized by a different, usually severe headache; it may also cause a range of additional neurological symptoms.13–16% of all people with vertebral or carotid dissection have dissection in another cervical artery. It is therefore possible for the symptoms to occur on both sides, or for symptoms of carotid artery dissection to occur at the same time as those of vertebral artery dissection. Some give a figure of multiple vessel dissection as high as 30%. Causes
The causes of vertebral artery dissection can be grouped under two main categories, spontaneous and traumatic. Spontaneous
Spontaneous cases are considered to be caused by intrinsic factors that weaken the arterial wall. Only a very small proportion (1–4%) have a clear underlying connective tissue disorder, such as Ehlers–Danlos syndrome type 4 and, more rarely, Marfan syndrome.
Medical professionals have suggested that the term sebaceous cyst be avoided since it can be misleading. : 31  In practice, however, the term is still often used for epidermoid and pilar cysts. Additional images
See also
Intracranial epidermoid cyst
List of cutaneous neoplasms associated with systemic syndromes
Proliferating epidermoid cyst
Verrucous cyst

References
External links

DermNet lesions/cysts