Not all patients who experience hallucinations have a psychotic disorder. Many physical and psychiatric disorders can manifest with hallucinations, and some patients have > 1 disorder that could cause different types of hallucinations. To avoid providing unnecessary or ineffective treatments--and to ensure that patients receive proper care for nonpsychiatric conditions--it is important to accurately diagnose the disorder causing a patient's hallucinations.

In this article we describe common features and psychiatnc and nonpsychiatric causes of auditory, visual, olfactory, gustatory, tactile, and somatic hallucinations. Awareness of typical presentations of hallucinations associated with specific disorders can help narrow the diagnosis and provide appropriate treatment.

Auditory hallucinations

Also known as paracusia, auditory hallucinations are perceptions of sounds without identifiable external stimuli. This type of hallucination has various causes (Table 1). (1) A frequent symptom of schizophrenia, auditory hallucinations can cause substantial distress and functional disability. (2) Approximately 60% to 90% of patients with schizophrenia and up to 80% of those with affective psychoses experience auditory hallucinations. (1)

Table 1

Common causes of auditory hallucinations

Peripheral lesions

Middle ear disease

Inner ear disease

Auditory nerve disease

CNS disorders

Temporal lobe epilepsy

Pontine lesions

Stroke

Arteriovenous malformations

Syncope

Toxic metabolic disturbances

Alcoholic hallucinosis

Delirium

Hallucinogens

Schizophrenia

Mania

Psychotic depression

Dissociative identity disorder

Posttraumatic stress disorder

Source: Reference 1

Clinical Point

Auditory perceptions of music have been associated with partial seizures

Auditory hallucinations in psychosis usually are formed and complex. (3) A common manifestation is hearing [greater than or equal to] 1 voices. A patient might experience 2 voices talking about him in the third person. The voices may be perceived as coming from inside or outside the patient's head. Some might hear their own thoughts spoken aloud. According to DSM-IV-TR, "hearing voices" is sufficient to diagnose schizophrenia if the hallucinations consist of a voice keeping up a running commentary on the person's behavior or [greater than or equal to] 2 voices conversing with each other. (4) Auditory hallucinations also are seen in mood disorders but tend to be milder than their psychosis-induced counterparts.

Simple (unformed) auditory hallucinations--referred to as tinnitus--can be caused by disease of the middle ear (otosclerosis) or inner ear. These unformed hallucinations consist of buzzing or tones of varying pitch and timbre. (1)

Partial seizures may cause auditory hallucinations. Perceptions of music have been associated with partial seizures. (5) Curie and colleagues found that 17% of 514 patients with temporal lobe epilepsy had auditory hallucinations as a component of their seizures. (6) These hallucinations typically are brief, stereotyped sensory impressions and, if formed, may be trivial sentences, previously heard phrases, or commands.

Alcoholic hallucinosis is a hallucinatory syndrome caused by alcohol withdrawal. These hallucinations usually are vocal and typically consist of accusatory, threatening, and/or critical voices directed at the patient. (1) Patients with alcohol hallucinosis also may experience musical auditory hallucinations. (7), (8)

CNS neoplasms can produce auditory hallucinations in 3% to 10% of patients. (9) Hemorrhages and arteriovenous malformations in the pontine tegmentum and lower midbrain have been associated with acute onset...