Synechiae (singular: synechia, alternative plural: synechias) are another term for adhesions, which in radiological contexts usually relates to bands of scar tissue between structures, e.g. within the abdominal cavity or pleural cavity or within the uterus.
Pathology
Synechia can be found throughout the body:
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nasal synechiae
adhesions between the lateral and medial (septal) walls of the nostril and usually occur post-surgery (e.g. FESS) or due to physical trauma
additional causes include chronic and recurrent nasal infections, nasogastric tube insertions, and post-cauterisation for bleeding
ocular synechiae: iris adheres to the trabecular meshwork (anterior synechiae) or anterior lens (posterior synechiae), usually as a result of inflammation
penile synechiae: tight attachment of the penile foreskin to the glans penis often a physiological and normal phenomenon in newborn infants and up to three years of age
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uterine synechiae
may occur due to curettage (repeated), chronic infections, caesarian delivery or myomectomy
Asherman syndrome is characterised by dysmenorrhoea, infertility and placental abnormalities and occurs due to uterine scarring and synechiae
venous synechiae: develop post-deep venous thrombosis following recanalisation and remodelling of the thrombus with the identification of a residual fibrous membrane or band within the lumen
vocal cord synechiae: scar tissue that prevents vocal cord function due to tethering and bridging of the vocal cords
vulvar synechiae: bridge(s) of tissue (skin) uniting the labia minora of the vulva; it is theorised that this condition occurs due to low oestrogen in prepubertal girls; poor hygiene and chronic dermal irritation may also predispose to developing vulvar synechaie
History and etymology
While adhesions have a Latin origin meaning 'sticking to' (compare the common English word 'adhesive'), synechiae are essentially the Greek equivalent, where συνέχεια/sunekheia means to hold (ἔχειν/ekhein) together (σύν/sun). Interestingly, the English word synechia is a Latinised version of the original Greek with one of the accepted plurals (synechiae) following the pattern of a first declension female Latin word – the actual Greek plural would be synechies (συνέχειες). This is a pattern that can be seen in other terms with non-Latin origins.