Even though the causes of<unk>  are not yet clear, there are two general theories that describe the etiology: the peripheral and central theories. In parosmia, the peripheral theory refers to the inability to form a complete picture of an odorant due to the loss of functioning olfactory receptor neurons. The central theory refers to integrative centers in the brain forming a distorted odor. In phantosmia, the peripheral theory refers to neurons emitting abnormal signals to the brain or the loss of inhibitory cells that are normally present in normal functioning. The central theory for phantosmia is described as an area of hyper-functioning brain cells that generate the order perception. Evidence to support these theories include findings that for the majority of individuals with distortions, there is a loss of sensitivity to smell that accompanies it and the distortions are worse at the time of the decreased sensitivity. It has been reported in parosmia cases that patients can identify triggering stimuli. Common triggers include gasoline, tobacco, coffee, perfum, fruits and chocolate. The cause of<unk>  has not been determined but there have been clinical associations with the neurological disorder: * Upper respiratory tract infection (URTIs) * Nasal and paranasal sinus disease * Toxic chemical exposure * Neurological abnormalities * Head trauma * Nasal surgery * Tumors on the frontal lobe or olfactory bulb * Epilepsy Most of cases are described as idiopathic and the main antecedents related to parosmia are URTIs, head trauma, and nasal and paranasal sinus disease. Psychiatric causes for smell distortion can exist in schizophrenia, alcoholic psychosis, depression, and olfactory reference syndrome.
Dysosmia
Anosmia
Aspermia
Dysmelia
Phantosmia
Hyperhidrosis
Dysacusis
Cynanthropy