A missing piece in the puzzle of chronic dizziness: Dysautonomia

Chronic dizziness is a complex symptom of multiple etiologies, which in neurology usually prompts an evaluation for vestibular migraine (VM) and persistent postural-perceptual dizziness (PPPD).(1) These two conditions share overlapping symptoms, such as dizziness, postural instability, fatigue, and sensory hypersensitivity, reflecting intricate pathophysiological mechanisms within the central nervous system. However, an important diagnostic entity often overlooked in the context of a patient presenting to a neurology clinic with chronic dizziness and headache is dysautonomia – a broad term encompassing autonomic dysfunction and autonomic disorders, such as Postural Orthostatic Tachycardia Syndrome (POTS), which is commonly comorbid with migraine.(2)

POTS, a chronic and disabling multisystemic disorder, is characterized by an abnormal heart rate increase of at least 30 beats per minute (bpm) in adults (or 40 bpm in children/adolescents) upon standing, without a significant change in blood pressure.(3) Patients experience orthostatic intolerance with symptoms, such as orthostatic dizziness, lightheadedness, fatigue, cognitive impairment (“brain fog”), blurred vision, and generalized weakness.(3) These symptoms are typically positional and improve when the patient assumes a supine position, but dizziness may also be chronic and non-positional in some patients. Diagnosis is confirmed through a 10-min stand test or a tilt table test.(3) The pathophysiology of POTS is multifactorial and involves sympathetic overactivity, hypovolemia, cerebral hypoperfusion and others, many of which are shared with migraine–one of its most common comorbidities.(2,4) Although migraine with and without aura appear to be the most common types in patients with POTS, vestibular and basilar migraine headaches are also frequently seen in this patient population though the prevalence of each migraine type has not been formally studied.

Emerging evidence suggests that brainstem dysregulation, central autonomic networks, and vestibular nuclei involvement are relevant to POTS pathophysiology.(4,5) These mechanisms may explain why patients with POTS often report vestibular symptoms similar to those seen in VM and PPPD. The overlap in clinical presentation underscores the need for careful diagnostic evaluation to avoid misdiagnosis. Treatment of POTS includes both nonpharmacologic and pharmacologic therapies, with beta blockers, such as propranolol and atenolol, being the first line medications for POTS, especially when migraine is a comorbidity.(2,4)

We emphasize the importance of inclusion of dysautonomia in the differential diagnosis of chronic dizziness, especially when symptoms are postural and chronic. Failure to consider autonomic disorders can lead to misdiagnosis, resulting in delayed or ineffective treatment. In clinical practice, a subset of patients with chronic dizziness or chronic migraine are deemed treatment-refractory when they have not responded to treatment of PPPD or migraine, and in many of these patients, etiology may be an undiagnosed and untreated autonomic disorder. Addressing this diagnostic and therapeutic gap is essential to improving patient care.

The differential neurologic diagnosis of dizziness and diagnostic criteria for PPPD, VM, and POTS are outlined in Table 1, which allows for inclusive and comprehensive differential neurologic diagnoses of chronic dizziness, especially with a postural component. These diagnostic criteria demonstrate distinct clinical features of each disorder and allow clinicians to avoid confusion, missed diagnosis and misdiagnosis.

Table 1.

Differential neurologic diagnosis of chronic dizziness: PPPD, VM, and POTS*

PPPD	VM	POTS
Diagnostic criteria (1)	Diagnostic criteria (1)	Diagnostic criteria (3)
Dizziness, unsteadiness, or nonspinning vertigo present on most days for ≥3 months.	At least five episodes of vestibular symptoms lasting 5 min to 72 h.	Heart rate increase ≥30 beats per minute (bpm) within 10 min of standing or a tilt table test for adults (≥40 bpm for adolescents age 12–19 years)
Symptoms exacerbated by upright posture, active/passive motion, or complex visual stimuli.	Current or past history of migraine with or without aura.	Symptoms of orthostatic intolerance for ≥3 months (dizziness/lightheadedness, palpitations, fatigue, brain fog and others)
Triggered by a vestibular, neurological, or psychological event.	One or more migraine features (migrainous headache, photophobia, phonophobia, or visual aura) with at least 50% of episodes	Absence of orthostatic hypotension
Symptoms cause significant distress or functional impairment.		Exclusion of other causes of postural tachycardia (e.g., dehydration, medication side effects, or other medical conditions)
Symptoms not better explained by another disorder.	Symptoms not better accounted for by another diagnosis.

*Data retrieved from Moreno-Ajona D et al.(1).

In summary, while chronic dizziness has a wide differential diagnosis, three common neurologic etiologies need to be considered in an outpatient evaluation: VM, PPPD and dysautonomia/POTS. As each disorder has its distinct diagnostic criteria, clinical features and diagnostic and therapeutic approaches, neurologists should become proficient in diagnosing all three conditions when evaluating a patient with chronic dizziness. POTS and other autonomic disorders are often not included in the neurology training curriculum, which leads to a lack of awareness and familiarity with these diagnoses for many neurologists. Clinical features, such as orthostatic intolerance, presyncope, syncope, fatigue and postural tachycardia, should prompt an evaluation in a patient with headache or chronic dizziness for common autonomic disorders via a 10-min stand test or a tilt table test. Accurate diagnosis and targeted therapies for dysautonomia patients who present with headache or chronic dizziness are essential to optimizing treatment outcomes and reducing functional impairment.