Recurrent Episodic Dizziness

Patients use the term “dizziness” to refer to many qualitatively different symptoms. Lightheadedness, such as is seen with presyncope, gait imbalance, true vertigo, and, not uncommonly, generalized weakness or mental slowing, may all be described as dizziness. While an attempt should be made to classify a patient’s complaint into one of these more precise categories, this is not always successful; patients frequently endorse more than one category or change categories on repeated questioning. Given this, when a patient reports episodic dizziness it is often more informative to ask what triggers the episodes and how long they last, as this information tends to be more reliable and is diagnostically useful. This chapter describes the approach to the patient with discrete episodes of dizziness which are consistent with vertigo, i.e., the sensation that the patient or their surrounding are moving when they are not.

A.

The presence of abnormalities on the standard neurologic examination raises concern for a brainstem or cerebellar lesion or a more diffuse central nervous system process, and brain magnetic resonance imaging (MRI) is warranted. If the patient reports the presence of any transient focal neurologic symptoms concurrent with their episodes of dizziness, this is particularly concerning for posterior circulation transient ischemic attack (TIA) and imaging of the posterior circulation with MR angiography should be considered. Importantly, the neurologic examination can be normal even in patients with brainstem or cerebellar lesions, and episodic vertigo with no other associated symptoms can occur with posterior circulation TIA. A high level of vigilance is thus required.
B.

The most common cause of brief (< 1 minute) episodes of vertigo triggered by positional change is benign paroxysmal positional vertigo (BPPV), which is particularly common in the elderly, though can affect those of any age. In BPPV, the discrete attacks of severe vertigo rarely last longer than 30 seconds; however, patients are often left with a vague sense of imbalance and very subtle vertigo that persists for much longer. When categorizing the duration of the episodes, the period of time during which symptoms were obvious and severe should be used.
C.

At some time in life, most people have experienced sudden lightheadedness (often interpreted as dizziness) due to orthostatic hypotension on rising suddenly from a recumbent position. A careful history establishing that episodes only occur when moving to an upright position indicates that orthostatic hypotension is the likely diagnosis. Note that many medications can contribute to this, particularly in older patients. Near immediate relief when returning to recumbency further establishes the diagnosis. As BPPV is also triggered by positional change, at times the distinction between BPPV and orthostatic hypotension can be challenging. Asking whether episodes ever occur with changes in head position not related to moving upright (e.g., rolling over in bed), and about the quality of the symptoms (i.e., lightheadedness versus true vertigo) may be useful. Very rarely, a patient with severe vertebral or basilar artery stenosis will experience TIAs triggered by reduced perfusion pressure when rising suddenly.
D.

The Dix-Hallpike maneuver is easily performed at the bedside; a positive test triggers the patient’s vertigo and causes torsional nystagmus with a brief latency and fatiguability. When these conditions are met, it is diagnostic for BPPV, which is caused by otoliths that have been displaced from the utricle into the semicircular canals. Otolith repositioning, also called the Epley maneuver, will cure about 80% of patients. Unfortunately, a negative Dix-Hallpike does not exclude the diagnosis of BPPV, and is in fact not at all uncommon in those with BPPV.
E.

Ménière disease is a chronic condition thought to be due to excessive accumulation of endolymph within the inner ear. It is characterized by repeated spontaneous attacks of vertigo, each lasting 20 min to 12 hours, low- to medium-frequency sensorineural hearing loss in the affected ear, and fluctuating aural symptoms such as tinnitus or a sense of fullness or pressure in the affected ear. Long-term treatment generally consists of a low sodium diet and thiazide diuretics.
F.

The head impulse test assesses the horizontal oculocephalic reflex. The patient is asked to fixate on a target like the examiner’s nose and while their head is rapidly moved to the right or left. A patient with an intact oculocephalic reflex will reflexively move their eyes in the opposite direction of head movement to maintain fixation. In a patient with an impaired oculocephalic reflex, their eyes will move with their head. To move their eyes back on the target, they will have a catch-up saccade in the opposite direction of the head movement. An abnormal head impulse test is usually but not universally indicative of an ipsilateral peripheral lesion, and in a patient with recurrent brief attacks of vertigo suggests a chronic, fixed peripheral vestibular lesion with breakdown of compensatory recovery under conditions of sudden position change. An example might be someone with prior vestibular neuritis and incomplete recovery.
G.

When the examination is normal despite provoking maneuvers, the cause of brief episodes of positional vertigo often remains elusive. BPPV is probably the most common cause, but any cause of chronic vestibular dysfunction may present this way.
H.

Vertigo associated with migraine (vestibular migraine) is probably an underappreciated cause of episodic vertigo. Headache is not always present concurrent with the attacks of vertigo, making diagnosis challenging. Prophylactic treatment is the same as for migraine in general. See Chapter 2 .
I.

Dizziness, unsteadiness or lightheadedness is seen in about 20% of patients with panic attacks, and is common in anxiety disorders in general. Dangerous causes, such as posterior circulation TIA, must be excluded before entertaining this diagnosis.