Pediatric emergency medicine trisk 0543 0543
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(accounting for the oculovestibular reflexes). Almost all patients complaining of
true vertigo should have nystagmus, at least when the vertiginous symptoms are
peaking. The fast component of the nystagmus is almost always in the same
direction as the perceived rotation.
DIFFERENTIAL DIAGNOSIS
As discussed earlier, dizziness is best divided into vertiginous conditions (true
vertigo) and nonvertiginous conditions (pseudovertigo). Table 24.1 lists the
differential diagnosis of true vertigo and highlights the life-threatening causes.
Table 24.2 lists the most common causes of vertigo. Table 24.3 lists numerous
nonvertiginous conditions that may initially be described as dizziness. Because
the spectrum of nonvertiginous conditions is so broad, the following discussion
will concentrate on true vertigo.
Vertigo follows a dysfunction of the vestibular system within the semicircular
canals, vestibule, or vestibular nerve (peripheral vertigo), or within the brainstem,
cerebellum, or cortex (central vertigo). It can also be divided into conditions in
which hearing is impaired (usually peripheral causes) and into conditions in
which hearing is spared (usually central causes) ( Table 24.1 ). Finally, vertigo
can be divided into acute (usually infectious, postinfectious, traumatic, or toxic)
and chronic-recurrent groups (usually caused by seizures, migraine, or benign
paroxysmal vertigo of childhood).
Infections
Both acute and chronic bacterial and viral infections of the middle ear, with or
without associated mastoiditis, may cause vestibular and auditory impairment
(see Chapters 34 Hearing Loss and 58 Pain: Earache ). Severe, untreated, acute
suppurative otitis media with effusion may extend directly into the labyrinth.
Even without direct invasion of pathogens, inflammation can cause labyrinthitis.
Chronic and recurrent otitis media can produce a cholesteatoma of the
tympanic membrane, an abnormal growth of keratinizing squamous epithelium
caused by repeated cycles of perforation and healing. Cholesteatomas can erode
the temporal bone and the labyrinth, producing a draining fistula from the
labyrinth that presents as vertigo, nausea, and hearing impairment. Computed
tomography (CT) scan or magnetic resonance imaging (MRI) shows destruction
of the temporal bone.
Viral infections can directly affect the labyrinth or the vestibular nerve;
together these conditions are known as vestibular neuronitis. Known pathogens
include mumps, measles, and the Epstein–Barr virus. Herpes zoster infection of
the ear canal and facial palsy (Ramsay Hunt syndrome) may also involve the
