Literature Review: A Roundup of Important Recent Studies

Bottom line: The recurrence rate underscores the surgical challenge, but the authors were unable to identify specific trends to demonstrate the superiority of one surgical approach over others.

Reference: Walgama E, Ahn C, Batra PS. Surgical management of frontal sinus inverted papilloma: a systemic review. Laryngoscope. 2012;122(6):1205-1209.

—Reviewed by Sue Pondrom

Clinical Tests of Peripheral Vestibular Function Are Reviewed

What is the anatomical and physiological evidence underpinning the tests of both canal and otolith function?

Background: The interpretation of vestibular test results depends heavily on basic anatomical and physiological information. New clinical tests of canal and otolith function have been introduced, but the anatomical and physiological evidence for their interpretation is not well known.

Study design: Contemporary review.

Setting: Vestibular Research Laboratory, School of Psychology, University of Sydney, New South Wales, Australia.

Synopsis: The author described tests of semicircular canal function, including the caloric test, head impulse testing and tests of static otolith function. Regarding primary physiological evidence, the author recapitulated the anatomical and physiological evidence about the otoliths. He put forward a hypothesis speculating that measuring oculomotor responses to air-conducted sound (ACS) and bone-conducted vibration (BCV) probes predominately utricular function, whereas measuring neck muscle responses to ACS and BCV mainly probes saccular function. He noted that this differential probing of utricular and saccular function is possible because of their differential neural projections.

In a section titled “Testing Dynamic Otolith Function by Vestibular-Evoked Myogenic Potentials,” the author discussed cervical vestibular-evoked myogenic potential (cVEMP) and ocular vestibular-evoked myogenic potential (oVEMP), noting that these tests are vestibular because patients who are totally deaf show the myogenic potentials to ACS or BCV, and patients after systemic gentamicin with likely absent vestibular function but residual hearing do not show the myogenic potentials. For clinical evidence, the author discussed dissociation and BCV versus ACS, including recent comparisons between the frequency response of oVEMPs to ACS and to BCV.

Bottom line: The overwhelming weight of physiological and clinical evidence supports oVEMP, but the exact mechanism by which BCV and ACS cause hair-cell deflections is not known. Additionally, when the results of oVEMP and cVEMP tests are combined with the results of other vestibular tests, the clinician can obtain a picture of the state of the peripheral vestibular function of each sense organ of the labyrinth.

Reference: Curthoys IS. The interpretation of clinical tests of peripheral vestibular function, Laryngoscope. 2012;122(6):1342-1352.

—Reviewed by Sue Pondrom

Identification of Prognostic Factors for Head and Neck Merkel Cell Carcinoma

What are the prognostic indicators for head and neck Merkel cell carcinoma (HN-MCC), and how do these compare with patients who have non-head and neck (NHN) MCC?

Background: MCC is a rare, aggressive cutaneous neoplasm that occurs most frequently in the head and neck region. Prognostic factors are not well characterized, but prognosis is considered poor. Whether HN-MCC requires separate consideration from MCC that occurs in other regions is uncertain.