Psychogenic dizziness
Synonyms and keywords: Functional dizziness; hyperventilation syndrome; nonspecific dizziness; phobic postural vertigo; psychiatric dizziness; psychic dizziness; psychophysiologic dizziness; somatization

# Overview
Psychogenic dizziness is a dizziness which is not characterized by true vertigo and it can be replicated by hyperventilation and psychiatric symptoms that usually precede its onset. It occurs in anxious or phobic individuals and do not include any specific symptoms. A new proposal narrowly defines psychogenic dizziness as the dizziness which occurs exclusively in combination with other symptoms as part of a recognized psychiatric symptom cluster and this symptom cluster is not itself related to vestibular dysfunction. Psychogenic dizziness should not be confused with the phenomenon of psychogenic overlay where the preexisting nucleus of nonpsychiatric dizziness is augmented by psychiatric factors that occur along with them. None of the personality disorders (DSM-IV Axis II psychiatric disorders) are characterized by dizziness or imbalance and thus they do not justify a diagnosis of psychogenic dizziness.

# Classification
The following classification has been proposed according to the newly proposed narrow definition of psychogenic dizziness:
- A psychiatric condition that entirely accounts for the patients dizziness like the panic disorder
- A cluster of anxiety disorders where dizziness is a part of their symptom cluster like the generalized anxiety disorder
- Psychiatric disorders where the psychiatric symptoms are vaguely described as having dizziness or imbalance by the patients like the description of poor concentration as swimming sensation in depressive disorders
- Psychiatric disorders which present with neurological symptoms including the symptom of imbalance which would fit in the narrow definition of psychogenic dizziness like the conversion disorder

# Pathophysiology
The following mechanisms mediate the relationship between anxiety disorders and vestibular disorders leading to a state of dizziness in psychiatric patients.

## Psychological Mechanism

### Somatopsychic
Patients may catastrophically interpret vestibular sensations as implying immediate danger and develop panic disorder which persists even after the resolution of the original vestibular disorder. Thus a somatic sensation becomes a psychic sensation.

### Psychosomatic
Increased arousal and hyperventilation leads to the occurrence of increased vestibular responses which are commonly seen in panic disorder with agoraphobia. Thus a psychic sensation turns into a somatic sensation.

## Neurophysiological Mechanism
Evidences suggest a neuroanatomic or neurophysiologic basis for the linkage between panic disorder and vestibular dysfunction. The current principal theory includes the dysregulation of brainstem noradrenergic systems, involvement of central serotonergic pathways and respiratory dyscontrol. The relationships between the structures of interest for panic disorder and vestibular system include the connections between locus coeruleus and lateral vestibular nucleus, the significant vestibular input to the raphe nuclei, the serotonergic effects on vestibular processes and vestibular-respiratory connection. Also, the nucleus parabrachialis receives vestibular and visceral input and is connected with the limbic system, including the amygdala which coordinates the autonomic and behavioral responses to emotional stimuli and is essential for the conditioning of fear responses.

# Causes
- Alcohol dependence
- Conversion disorder
- Fibromyalgia
- Generalized anxiety
- Hyperventilation
- Major depression
- Panic disorder