![]() ![]() Brain gamma-aminobutyric acid levels are decreased in patients with phantageusia and phantosmia demonstrated by magnetic resonance spectroscopy. Taste and smell phantoms revealed by brain functional MRI (fMRI). Physiologically initiated and inhibited phantosmia: Cyclic, unirhinal, episodic, recurrent phantosmia revealed by brain fMRI. ![]() Olfactory hallucinations without clinical motor activity: a comparison of unirhinal with birhinal phantosmia. Taste and smell function in chronic disease: A review of clinical and biochemical evaluation of taste and smell dysfunction in over 5000 patients at The Taste and Smell Clinic in Washington, DC. Treatment with repetitive transcranial magnetic stimulation (rTMS), which usually increases brain GABA, also inhibits presence of these hallucinations (2-4). Treatment with GABAergic drugs which increases brain GABA levels have inhibited presence of these hallucinations (2,5). We have discovered through use of magnetic resonance spectroscopy (MRS) that brain gamma-aminobutyric acid (GABA) levels are diminished in patients with all types of these hallucinations (5). Some of the same characteristics we have discussed about olfactory hallucinations also have similarities to the characteristics of phantom limb syndrome. These phantoms are similar to phantoms which occur after a limb amputation which has been termed phantom limb (1). Whereas exposure to a strong external odor may last only for a few seconds, onset of the subsequent olfactory hallucination may be initiated in length and/or intensity as occurred during its spontaneous generation. REM sleep has no effect on hallucination elimination.įor some patients exposure to a strong external odor can initiate the underlying hallucination. The type of sleep which accomplishes this inhibition is Stage IV sleep when most neural activity is either inhibited or significantly reduced. ![]() This pattern lends to the response that hallucination intensity is less intense in the morning but becomes more intense in the afternoon and most intense in the evening. Most patients report that sleep inhibits the hallucination regardless of the cause (2,3). In these patients performance of a valsalva-type maneuver usually terminates the hallucination but it always recurs (2-4). This small group of patients develops onset of these odors after a sneeze, cough, laughing or crying (3). However, there are a small group of patients in whom these hallucinations occur on only one side of their nose, hence unirhinal (2-4). Most often these hallucinations fill the entire nasal cavity and are birhinal (1,2). This is called an aura and it may precede a myoclonic seizure, usually of a simple, partial type. The odor itself may also act as a prodrome to a subsequent neurological event. However, patients do report a prodrome on occasion which alerts them that the odor may occur. They occur spontaneously without any specific warning. Most often they appear in the absence of any external odor (1). They are prominent enough to disrupt the patient’s ability to perform normal daily tasks. They can persist for days, weeks or months and never disappear. However, they can also last a few minutes to longer. They can also occur recurrently, sometimes as often as 10-20 times per day. They usually occur once and then disappear. Most often these hallucinations are transient (1,2), lasting seconds. Occasionally these hallucinations have a mixed quality, both chemical and rotten. ![]() Among the rotten odors – they are almost always fecal. Rarely they exhibit a sweet character which is usually considered cloying and overly sweet. Among the chemical odors – they can be salty or burned, metallic, bitter or difficult to describe. They have either a chemical ( torquosmia) or rotten ( cacosmia) character. Olfactory hallucinations are usually negative and unpleasant in character. Their presence is uniformly disturbing and cause disruptions to the normal course of living due to the profound negative effects of their presence (1). Olfactory hallucinations have been labeled olfactory phantoms or phantosmias (1). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |