General information
The upper eyelid is lifted by two different muscles together, thus opening the eye, the musculus levator palpebrae superioris (involuntarily innervated by the nervus oculomotorius) and the musculus tarsalis (involuntarily innervated by the sympathetic nervous system). The latter works noticeably less in cases of fatigue, as the activity of the sympathetic nervous system decreases accordingly and it is difficult to keep one’s eyes open (ptosis causes).
Forms
Causes of ptosis are all congenital and acquired damage on the route between the brain area of one of the two lid-lifting muscles, via the path of the responsible nerves, up to the individual muscles themselves (ptosis causes).
Congenital ptosis
As a rare form, ptosis is congenital. It usually occurs unilaterally and is caused by underdevelopment or non-application of the core area of the oculomotor nerve or the muscle itself. It can be associated with various maldevelopment syndromes, but can also occur in isolation due to a genetically inherited or acquired component.
A tumor (usually as a hemangioma) of the upper eyelid or the Marcus Gunn syndrome, in which there is a misaligned triggering between the masticatory muscles and the muscle levator palpebrae superioris, can also be the cause of ptosis at birth. Irrespective of the cause of congenital ptosis, it represents a high risk of amblyopia (weakness of vision) for the newborn in the further course of the disease, since the visual pathway only fully matures under the first sensory impressions and this is not possible if the iris is partially or completely covered. For this reason, congenital ptosis is operated on early.
If damage to the voluntary nerve tracts (N. oculomotorius) occurs on the stretch between the eye muscle nuclei and the musculature, this is called paralytic ptosis. It can also be caused by a reduced blood supply to the cerebral nerve core area in the brain stem, but is then usually accompanied by other symptoms. A compression of the nerve by a tumor or aneurysm in the brain stem area or in its further course, as well as traumatic damage caused by an accident are possible (ptosis causes).
If the cerebral pressure rises, the oculomotor nerve may become trapped at the base of the skull. A sinus-cavernosus syndrome, in which thrombosis, vascular anomalies, inflammatory processes or other new formations can lead to a space requirement in the venous cistern called sinus cavernosus, which is located behind the eye sockets and in the vicinity of the sphenoidal sinus cavity, also leads to impairment of the oculomotor nerve, but also of various other nerves. Since the oculomotorius nerve also controls almost all other internal and external eye muscles, damage not only leads to ptosis, but also to double images due to certain strabismus patterns, accommodation difficulties and increased light sensitivity due to the disturbed iris closure (ptosis causes).
