Introduction /Anatomy
The chiasma is the junction of the optic nerve. Here, the fibres of the respective nasal retinal halves of both eyes cross to the opposite side. The optic tract follows the chiasm. Injuries to the optic chiasm lead to the chiasm syndrome.
Definition
Chiasma syndrome is the name given to an occurrence of three typical characteristics:
- Bitemporal facial loss (which means that the visual impression is only missing on the outside, i.e. there is a blinkered vision)
- Reduction of visual acuity on one or both sides
- Optic atrophy (destruction of nerve cells of the optic nerve)
Very typical for the Chiasma syndrome are The disturbances in hormone balance are caused by the frequent tumors of the pituitary gland. The pituitary gland is the regulating unit in the release of hormones. The bitemporal failures (only on the outside) of the visual field are caused by the space requirement pressing on the centre of the optic nerve crossing and thereby compressing mainly the fibres of the nasal retinal halves.
The nasal retinal halves represent the corresponding parts of the visual field, namely the temporal, i.e. outwardly located halves. – frequent headaches
- Hormonal imbalances and
- Double images. In addition to defects in the visual field, radiographic changes of the sella turcica (Turkish saddle) are also detected.
This is a bony structure of the base of the skull in which the pituitary gland (hypophysis) is located. Tumours of the pituitary gland must be removed. After relief, visual acuity and the visual field can recover.
However, long-term damage cannot be excluded. The cause is usually a mass (usually tumours) that presses on the chiasm. In most cases it is a tumour of the pituitary gland (pituitary gland), more rarely the symptoms are caused by a tumour originating from the meninges (meningioma).
Furthermore, an aneurysm (widening) of vessels (often carotid artery = med. carotid) can compress the optic nerve crossing and cause symptoms. Also, masses of the optic nerve itself (gliomas = benign tumor) can extend to the chiasma. – Cerebrum
- Cerebellum
- Spinal cord
- Pituitary gland
