B30. Characteristic appearance of harmonic and disharmonic vestibular syndromes

Vertigo is the a symptom characterised by the sensation that you are moving, or everything moves around you. Vertigo occurs due to dysfunction of the vestibular system or the parts of the CNS involved with the vestibular system. It's a common symptom in a variety of disorders, ranging from harmless to life-threatening. Many patients use the term "vertigo" when referring to dizziness, which is a nonspecific term used to mean many different symptoms.

Acute vestibular syndrome is defined as the presence of severe vertigo lasting more than 24 hours which causes nausea and vomiting and an intolerance to head movement (because it makes the vertigo worse).

We distinguish vertigo due to central (CNS) causes and peripheral (vestibular system) causes. In Hungarian literature, peripheral vertigo is called harmonic vestibular syndrome while central vertigo is called disharmonic vestibular syndrome.

	Peripheral vertigo (harmonic vestibular syndrome)	Central vertigo (disharmonic vestibular syndrome)
Nystagmus direction	Never changes direction Fast component away from affected ear. (Slow component toward affected ear)	Direction may change based on gaze Fast component toward affected side. (Slow component away from affected ear)
Nystagmus type	Horizontal or combined horizontal and rotational Never purely rotational or purely vertical	Any direction Purely vertical or purely rotational is always central
Sense of motion	Severe, nausea and vomiting common	Usually mild
Romberg test	Patient falls toward the affected ear	Patient falls toward the affected side
Does visual fixation suppress nystagmus?	Yes	No
Postural instability	Instability toward affected side Walking usually preserved	Severe instability Walking usually difficult
Other inner ear symptoms (hearing loss, tinnitus)	May be present	Usually not present
Ataxia, diplopia, dysphagia, weakness, other neurological symptoms	Absent	Often present