Blockage of longitudinal flow in endolymphatic hydrops

Abstract

The external shunt operation on the endolymphatic sac is based on the concept that it will drain excess endolymph and thus arrest the progression of endolymphatic hydrops. We performed histological studies on 46 temporal bones from 13 cases of bilateral and 20 cases of unilateral Meniere's disease to evaluate the status of the pathways of longitudinal flow of endolymph to the sac. The endolymphatic ducts were blocked in 8 specimens (17%), the endolymphatic sinuses in 9 (19.5%), the utricular ducts in 12 (26%), the saccular ducts in 7 (15%), and the ductus reuniens in 27 (59%). These blockages arrested longitudinal flow from both the pars superior and inferior in 21 cases (46%), the pars superior only in 3 (6.5%), and the pars inferior only in 16 (35%). In the 6 ears with all pathways open, 2 were found to have fistulae between the saccules and the perilymphatic spaces, which theoretically results in internal shunting, thus alleviating the need for the external shunt procedure. In the aggregate, therefore, 42 (91%) of 46 ears showed either areas of blockage of longitudinal flow or internal shunts that would theoretically negate the value of external endolymphatic shunt procedures. These temporal bones, however, are from an autopsy population and the severity of pathological changes is probably greater than it would have been at an earlier age when external shunt surgery might have been a therapeutic consideration.

Changes in the Tullio Phenomenon and the Fistula Sign in the Course of Endolymphatic Hydrops

“…Okuno and Sando [1] histopathologically determined that severe endolymphatic hydrops in Ménière's disease develops most frequently in the saccule, followed by the cochlea, utricle, and the three semicircular canals. Blockage of the endolymphatic pathways in the endolymphatic duct, endolymphatic sinuses, utricular ducts, saccular ducts, or ductus reunions has been demonstrated to induce endolymphatic hydrops in corresponding portions of the inner ear [2]. Endolymphatic hydrops may be limited to the saccule and/or the three semicircular canals during the course of Ménière's disease.…”

A Possible Case of Saccular Endolymphatic Hydrops

“…Obstruction of the saccular duct causes endolymphatic hydrops in the pars inferior, and that of the utricular duct causes endolymphatic hydrops in the pars superior. Distorted otolith membranes result in blockage of the duct [15]. The saccular wall is more yielding than the utricular wall [16]; thus, obstruction of the saccular duct may occur more often than that of the utricular duct.…”

“…Ruther [15], 3 of 46 temporal bones of patients with Ménière's disease had a blocked saccular duct and an intact utricular duct. Our case was thought to be similar to those mentioned above.…”

Endolymphatic Hydrops in Children

“…Based on the concept of longi tudinal flow of endolymph, outlet obstruction at the duc tus reuniens is considered to be a major etiological factor in the development of EH [15,20,22], Schuknecht and Rüther [ 15] reported a blocked ductus reuniens in 59% of temporal bones in patients with Meniere's disease (aver age age 70.6 years). In our study of children's temporal bones, we also found a high percentage (49.2%) of col lapsed ductus reuniens.…”

“…Obliteration of the ductus reuniens is considered by some authors to be an etiological factor for cochlear EH [15,16]. The size of the ductus reuniens was classified into three diameters -wide, narrow and collapsed ( fig.…”