By Marcello Cherchi, MD PhD
For clinicians
The Valsalva maneuver was first described by Antonio Maria Valsalva in 1704 (Valsalva 1704). The maneuver originally described by Valsalva was a method of inflating the middle ear by forced nasal expiration with the nose and lips closed. For this technique, there is increased intrathoracic pressure as well as increased upper airway pressure. Subsequently, the method of doing the “Valsalva maneuver” was modified so that it was performed against a closed glottis; this technique avoids changing middle ear pressure (since the pressure differential ends at the glottis and does not get transmitted to the pharyngeal orifice of the Eustachian tube), but retains the effect on intrathoracic pressure. Here we will be discussing the form with the glottis closed, but the reader should be aware that the term “Valsalva maneuver” is used for two distinct techniques.
Performing the Valsalva maneuver against a closed glottis results in a nearly simultaneous increase in intrathoracic pressure, which is transmitted intraspinally and thence intracranially (Hamilton, Woodbury, Harper 1936; Williams 1981). In patients with superior semicircular canal dehiscence (SSCD) (Minor et al. 1998), the increased intracranial pressure can be transmitted from there through the dehiscence into the superior semicircular canal and (since the labyrinth is a continuous space) the remaining vestibular and cochlear structures. That pressure differential can stimulate the superior semicircular canal and provoke nystagmus in the plane of that canal (Cremer et al. 2000). Sometimes the naturally occurring intracranial pressure oscillations resulting from the cardiac pulse are sufficient to be transmitted to the superior semicircular canal and provoke nystagmus (even without performing the Valsalva maneuver) (Tilikete et al. 2004; Younge et al. 2003).
The Valsalva maneuver normally provokes no nystagmus in healthy individuals, thus there is no normative range associated with this examination of the ocular motor examination.
References
Cremer PD, Minor LB, Carey JP, Della Santina CC (2000) Eye movements in patients with superior canal dehiscence syndrome align with the abnormal canal. Neurology 55: 1833-41. doi: 10.1212/wnl.55.12.1833
Hamilton WF, Woodbury RA, Harper HT, Jr. (1936) Physiologic relationships between intrathoracic, intraspinal and arterial pressures. Journal of the American Medical Association 107: 853-856. doi: 10.1001/jama.1936.02770370017005
Minor LB, Solomon D, Zinreich JS, Zee DS (1998) Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal. Arch Otolaryngol Head Neck Surg 124: 249-58. doi: 10.1001/archotol.124.3.249
Tilikete C, Krolak-Salmon P, Truy E, Vighetto A (2004) Pulse-synchronous eye oscillations revealing bone superior canal dehiscence. Ann Neurol 56: 556-560. doi: PMID: 15455401
Valsalva AM (1704) De Aure Humana Tractus, Bologna
Williams B (1981) Simultaneous cerebral and spinal fluid pressure recordings. Acta Neurochir (Wien) 58: 167-185. doi: PMID 7315549 (paper copy at Galter)
Younge BR, Khabie N, Brey RH, Driscoll CL (2003) Rotatory nystagmus synchronous with heartbeat: a treatable form of nystagmus. Trans Am Ophthalmol Soc 101: 113-7; discussion 117-8.
