A simple standard technique for labyrinthectomy in the rat: A methodical communication with a detailed description of the surgical process

Abstract

Aims: Labyrinthectomized rats are suitable models to test consequences of vestibular lesion and are widely used to study neural plasticity. We describe a combined microsurgical-chemical technique that can be routinely performed with minimum damage. Methods: Caudal leaflet of the parotis is elevated. The tendinous fascia covering the bulla is opened frontally from the sternomastoid muscle's tendon while sparing facial nerve branches. A 4 mm diameter hole is drilled into the bulla's hind lower lateral wall to open the common (in rodents) mastoid-tympanic cavity. The cochlear crista (promontory) at the lower posterior part of its medial wall is identified as a bony prominence. A 1 mm diameter hole is drilled into its lower part. The perilymphatic/endolymphatic fluids with tissue debris of the Corti organ are suctioned. Ethanol is injected into the hole. Finally, 10 μL of sodium arsenite solution (50 μM/mL) is pumped into the labyrinth and left in place for 15 min. Simple closure in two layers (fascia and skin) is sufficient. Results and conclusion: All rats had neurological symptoms specific for labyrinthectomy (muscle tone, body position, rotatory movements, nystagmus, central deafness). Otherwise, their behavior was unaffected, drinking and eating normally. After a few days, they learned to balance relying on visual and somatic stimuli (neuroplasticity).

Surgical Labyrinthectomy of the Rat to Study the Vestibular System

“…A mechanical drilling system results in less fenestration trauma and helps to obtain consistent results. Without ethanol irrigation, we observed variable behavioral responses after the labyrinthectomy 13,17 . Ethanol irrigation and suction ensure that the labyrinth is terminally damaged.…”

“…Ethanol irrigation and suction ensure that the labyrinth is terminally damaged. 13 Blunt electrical coagulation of the vestibular nerve can be performed via this hole 22 . Proper magnification is essential, and a microscope is mandatory in most cases.…”

“…NOTE: The loss of vestibular function can be evaluated using either behavioral or vestibular function tests. 13,17,18 Behavioral tests include the evaluation of postural asymmetry and nystagmus.…”

“…Surgical labyrinthectomy is a specific, reliable, and relatively simple method. 13,14 Moreover, the symptoms of vestibular damage are seen immediately after surgery. Here, we describe our surgical technique for rat labyrinthectomy.…”

“…Several behavioral and vestibular function tests can be used to confirm that the labyrinthectomy has been performed successfully 13,14 .…”