Objective: It has been documented in the literature that caloric responses are reduced, but not absent with the lateral semicircular canal in a horizontal position. This chapter addresses what contributions to the caloric response are made by the macula of the utricle and saccule, and their contribution to how the vestibular system functions in Earth’s only bipedal mammal. This study has also discussed the complexity of balance maintenance, emphasizing the importance of the poorly understood striated organelle (STO). This structure is a contractile protein complex and is fundamental to balance function in all animals and up to now, its significance in the only mammalian biped has previously been poorly appreciated and almost disregarded.
Methods: This study is a prospective case series which was
arranged and conducted at a tertiary and quaternary care teaching hospital. 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 documented by abnormal VEMP assessment). Two sets of
caloric tests (standard and horizontal) were carried out on our subjects.
Patients underwent identical caloric assessment after CVEMP and OVEMP
assessment. VEMPs were scored as either normal or abnormal for each parameter
assessed. Caloric tests 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.
Conclusions: Caloric responses are modulated by head position and
in patients with otolithic pathology, semicircular canal function is further
modulated, as caloric responses are different in patients than in normals when
the lateral semicircular canal orientation to gravity is changed. Our results
suggest that the otoliths mediate caloric responses.
Author
(s) Details
NS Longridge
Division of Otolaryngology, Department of Surgery, Faculty of Medicine,
University of British Columbia, Canada.
AI Mallinson
Division of Otolaryngology, Department of Surgery, Faculty of Medicine,
University of British Columbia, Canada.
DD Pothier
Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine,
University of Toronto, Canada.
J Rutka
Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine,
University of Toronto, Canada.
Please see the book here:- https://doi.org/10.9734/bpi/msti/v6/4195
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