The saccule is the most mysterious organ of the labyrinth and, for this reason, one of the most fascinating. For anatomic, embryologic and physiologic reasons the saccule has both auditory and vestibular characteristics, being the connecting link between the vibratory energy and the vestibular response: it is an anatomic bridge between the anterior and the posterior labyrinth; it has a common embryologic origin with the cochlea in the pars inferior of the labyrinth; it is the main hearing organ in fish and other ancestral vertebrates. The saccule is an otolith organ involved in vertical linear movement detection and sensing gravitational changes; it controls the tonic components of the antigravity muscles contributing to the postural control. In addition, through the vestibule-sympathetic reflexes, it contributes to the control of blood pressure during movement and through postural changes. The aim of this presentation is to show why the saccule should be taken into consideration for certain forms of tinnitus. The anatomical proximity of the saccule to the stapes suggests that an excessive pressure on the footplate may damage the saccular neuroepithelium which lies close to the oval window. The principal mechanisms suspected of being involved in saccular dysfunction are: • chronic noise exposure [1,2]. • tonic tensor tympani contraction [3] • Disturbance of blood circulation, aging, trauma. While the effects of detached utricular otoconia are generally accepted as the cause of Benign Paroxysmal Positional Vertigo, what happens to saccular otoconia? Gussen (1980) reported that a suffering saccular macula dislodges otolith debris that could reach the cochlea through the ductus reuniens and cochlear duct, thus also affecting the cochlear base and the high frequency hearing thresholds.[4] An intermittent tinnitus has been described in patients with by BPPV, in the same ear affected by the lithiasis (Barozzi et al. 2014)[5] Recently detached saccular otoconia have even been suggested as pathophysiological cause of Ménière disease (Hornibrook and Bird, 2017) [6,7]. We suggest that saccular debris can fall into the ductus reuniens and thereby disturb the endolymphatic flow in the cochlear base. This event can play a role in some ear symptoms, such as certain cases of tinnitus, fullness, mild vertigo/nausea, slight hearing loss or Ménière-like findings in patients with asymmetric VEMPs. A possible role of the saccule should be considered in tinnitus. This also corroborates the theory of the evolutionary basis of tinnitus as stimulus of alertness or vigilance that may have survival value; as the saccule controls the tonic components of the antigravity muscles, it could therefore participate in “fight or flight” responses.[8] Based on these considerations, a cooperation between specialists of various disciplines (neurootologists, radiologists, neurophysiologists, cardiologists and dentists)would be beneficial to fully characterize the role of the vestibular organ on tinnitus.

Saccule and tinnitus: a possible connection? / S. Barozzi, D. Alpini, P. Giovanni, Luca Del Bo. ((Intervento presentato al convegno First World Tinnitus Congress ; XII International Tinnitus Seminar tenutosi a Warsaw nel 2017.

Saccule and tinnitus: a possible connection?

S. Barozzi;ALPINI, DARIO;
2017-05

Abstract

The saccule is the most mysterious organ of the labyrinth and, for this reason, one of the most fascinating. For anatomic, embryologic and physiologic reasons the saccule has both auditory and vestibular characteristics, being the connecting link between the vibratory energy and the vestibular response: it is an anatomic bridge between the anterior and the posterior labyrinth; it has a common embryologic origin with the cochlea in the pars inferior of the labyrinth; it is the main hearing organ in fish and other ancestral vertebrates. The saccule is an otolith organ involved in vertical linear movement detection and sensing gravitational changes; it controls the tonic components of the antigravity muscles contributing to the postural control. In addition, through the vestibule-sympathetic reflexes, it contributes to the control of blood pressure during movement and through postural changes. The aim of this presentation is to show why the saccule should be taken into consideration for certain forms of tinnitus. The anatomical proximity of the saccule to the stapes suggests that an excessive pressure on the footplate may damage the saccular neuroepithelium which lies close to the oval window. The principal mechanisms suspected of being involved in saccular dysfunction are: • chronic noise exposure [1,2]. • tonic tensor tympani contraction [3] • Disturbance of blood circulation, aging, trauma. While the effects of detached utricular otoconia are generally accepted as the cause of Benign Paroxysmal Positional Vertigo, what happens to saccular otoconia? Gussen (1980) reported that a suffering saccular macula dislodges otolith debris that could reach the cochlea through the ductus reuniens and cochlear duct, thus also affecting the cochlear base and the high frequency hearing thresholds.[4] An intermittent tinnitus has been described in patients with by BPPV, in the same ear affected by the lithiasis (Barozzi et al. 2014)[5] Recently detached saccular otoconia have even been suggested as pathophysiological cause of Ménière disease (Hornibrook and Bird, 2017) [6,7]. We suggest that saccular debris can fall into the ductus reuniens and thereby disturb the endolymphatic flow in the cochlear base. This event can play a role in some ear symptoms, such as certain cases of tinnitus, fullness, mild vertigo/nausea, slight hearing loss or Ménière-like findings in patients with asymmetric VEMPs. A possible role of the saccule should be considered in tinnitus. This also corroborates the theory of the evolutionary basis of tinnitus as stimulus of alertness or vigilance that may have survival value; as the saccule controls the tonic components of the antigravity muscles, it could therefore participate in “fight or flight” responses.[8] Based on these considerations, a cooperation between specialists of various disciplines (neurootologists, radiologists, neurophysiologists, cardiologists and dentists)would be beneficial to fully characterize the role of the vestibular organ on tinnitus.
Settore MED/32 - Audiologia
Settore MED/31 - Otorinolaringoiatria
Saccule and tinnitus: a possible connection? / S. Barozzi, D. Alpini, P. Giovanni, Luca Del Bo. ((Intervento presentato al convegno First World Tinnitus Congress ; XII International Tinnitus Seminar tenutosi a Warsaw nel 2017.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/543074
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