Do Otoliths Modulate Caloric Response? What Do Vemps and Cdp Measure? What Do These Tests Tell Us?

Abstract

Objective: it has been documented in the literature that caloric responses with the lateral semicircular canal in a horizontal position are reduced, but not absent. This paper addresses what contributions to the caloric response, if any are made by the otoliths, and what influences on caloric response might be seen in patients with otolithic pathology.Study design: a prospective case series study.Setting: Tertiary and quaternary care teaching hospital.Patients: two normal subjects underwent "horizontal" calorics to document caloric response with the lateral semicircular canal in the horizontal position. This assessment was also carried out on eight sequential patients who were documented to have otolithic disease (as evidenced by abnormal VEMP assessment). Interventions:Two sets of caloric tests (standard and horizontal) were carried out on our subjects. Patients underwent identical caloric assessment after CVEMP and OVEMP assessment. Main outcome measures:VEMPs were scored as either normal or abnormal for each parameter we assess. Calorics were scored using the standard slow phase velocity measurements for each one.Results: Patients with otolithic abnormalities showed different caloric results in the horizontal position than is suggested in the literature and was shown by our two normal subjects. Conclusion:Caloric responses are modulated and in patients with otolithic pathology, semicircular canal function is modulated, as caloric responses are different in patients than in normals when the lateral orientation to gravity is changed. Our results suggest that the otoliths do in fact mediate caloric responses.

A Review of the Literature to Outline How the Vestibular Efferent System Correlates the Complexity of Routine Balance Maintenance with Management of Emergency Fall Prevention Strategies

“…In no particular order, these are: A. to foveate; i.e., maintain eye fixation on a target during head movement. This is predominantly a semicircular canal task, although semicircular canal activation is modulated by the maculae of the utricle and saccule [14]. B. to provide information regarding change of head position during movement of the neck or the body as a whole, during perambulation; this is a macular function; C. to provide a constant information flow with regard to the relationship of the head (and therefore the body) to gravity; this is also a macular function.…”

A New Perspective to Interpret How the Vestibular Efferent System Correlates the Complexity of Routine Balance Maintenance with Management of Emergency Fall Prevention Strategies

“…In no particular order, these are as follows: To foveate; i.e., maintain eye fixation on a target during head movement. This is predominantly a semicircular canal task, although semicircular canal activation is modulated by the maculae of the utricle and saccule [ 14 ]. To provide information regarding change of head position during movement of the neck or the body as a whole, during perambulation; this is a macular function.…”

“…To foveate; i.e., maintain eye fixation on a target during head movement. This is predominantly a semicircular canal task, although semicircular canal activation is modulated by the maculae of the utricle and saccule [ 14 ].…”

Critical Cochlea/Vestibular Interactions

“…The system can be disconnected urgently if a sudden external stimulus sound or a visual stimulus calls for a rapid head turn and in these circumstances the vestibulo-ocular reflex [VOR] is instantly switched off. There is a coordination with the macula system [32] but this chapter is not the place to discuss the details of how [VOR] function works as it is not specifically related to vibration effects of sounds inside the head and their effect on macula function.…”