Renato Cocchi, a neurologist and a medical psychologist.


This article is a report of a case history of intermittent pure cacosmia-phantosmia, without any anosmia, hyperosmia and ageusia, lasting 14 years, in a man of 40 years. This symptom comes out without any apparent reason or from strongly olfactory stimulus, and it disappears during the sleep.

A trial of a drug therapy aiming to improve presumable brain neurochemical deficits or excesses was carried out, which lasted only 33 days, since the patient did not come back to check. The accurate description of the case permitted to think a possible neuropathological explanation out.

Key words: Cacosmia, phantosmia, intermittence, sleep, man, glutamate, drug therapy, explanation, hypothesis.


Italian translation

Drug modulation of stress reactions

Anosmia, hyperosmia ecc.

Stress and depression

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It came to my observation a pure case of intermittent cacosmia-phantosmia, without any anosmia, hyperosmia and ageusia, lasting 14 years, in a man of 40 years. Since the exceptionally morbid condition so long lasting, which I initially treated it with drug therapy, then stopped by the patient, I however wrote here its history as it follows.


The case history.

A male of 40 years at first consultation, an employee in the private tertiary sector. His female engaged, a physician, so described his illness, in a request for consultation sent by email.

"Since about 14 years he is suffering from very troublesome cacosmia. We stay together since several years and I observed that the first heavy olfactory stimulus or such perceived by him, he fit comes out. This consists in the feeling of the nonexistent unpleasant smells or existing but greatly modified smell always in an unpleasant sense. This fit goes on till that he goes to bed and it ends during the nighttime sleep. Except it restarts according to the first stimulus of the following morning, that usually comes back much early.

In facts, last times he found a way to interrupt the fit till the following stimulus. In practice, he folds up on himself as to touch with his hands the peaks of the feet and does a forced expiration with the closed glottis for some seconds. It is like, to understand, a manoeuvre of Valsalva. You can well figure out how this manoeuvre, in that position, increases in a dangerous way the endocranial pressure. By repeating it 5-10 times daily, it is not healthy. According to direct evidence, after I advised him since a long time, about a week ago he elicited a right low eyelid hematoma that is much slowly reabsorbing. From that day I absolutely forbid him to repeat this manoeuvre.

Therefore of all that it is that the fit arrives in the morning and lasts all day long. You may imagine how much this situation can be psychologically disabling a person, even in his work setting.

Following the suggestion of a Canadian professor, contacted trough Internet, as an expert in this field, which name now escapes to me, he tried the gabapentin but without any benefit. We required and performed olfactory tests in USA that resulted in very light anomalies. A CAT acted some years ago, did not show anything of remarkable as for the brain."

June 2004: The first consultation. A man suffering from cacosmia, that started 14 years ago. He says that this trouble may last even all day long. In facts, during the sleep the cacosmia interrupted, but it can come back even early in the morning and it can stay so till the following falling asleep. It can follow the perception of an odour, which feels distorted or it can begin without any olfactory stimulus. They are not anosmia, hyperosmia and ageusia. The foods' odour, however, mainly of the coffee, may switch the attack of cacosmia.

There is not any progression in the cacosmia intensity. If the "fit" starts, it starts already at the maximum level of intensity. The long lasting in hours leads to exclude that it is an epileptic or epileptoid phenomenon. In the performed EEGs anything abnormal was never found.

Currently he attends a gym, in the evening, but the physical exercise doesn't stop the current episode of cacosmia, neither it modified the frequency of the attacks. When he does not sleep enough, the fit goes on. On suggestion of a Canadian expert he assumed gabapentin 200mg daily, without any result. When he has migraine attacks, with alternating sides, some times he has an attenuation. The fragrant stimulation (EG. cars' exhausting gases, bath salts, cigarette smoke, coffee, toilet perfumes) or when he blows his nose, are all triggering factors. To the test: Which is the opposite of the colour Red? he answers: Black [?]. The question put him into uneasiness because he did not obey at once to the previous instructions. As reproached for it, he had an emotional reaction and this triggered a cacosmia attack (at 12:20 PM), which did not yet came out today. He has dysphoric moments.

By travelling with a car and however with any locomotion tool does not change the frame. The episode frequency does not vary. Even sexual intercourse does not change the current fit, but it hardly starts the fit.

There is no report of pregnancy or delivery problems. His birth was in the term, with birthweight of 3600 grams. In the first year life there were no symptoms and behaviour that could do to think to some brain suffering and he denies any cranial trauma. He was always a serene child. At school he did better mathematics. Usually, he bears well light, noise and confusion. He suffers from the cold, has normal hair, no intrusive thinking, but he inclines to the "negative thought": In facts, he is apprehensive (he sees always the half-filled glass, as half-empty). He doesn't count objects without any reason, has no drooling during the sleep, doesn't talk when sleeping, does not suffer from nighttime muscular cramps, but from rare bruxism. When awaking, he does not feel tired. He need to have breakfast at once. He appreciates normally sweet things and meat broth, but he does not like the milk, while dairy products in a normal way. In the foods' choice, he is a little fussy.

No dental shut, no redness of the eyes occurred, also no dizziness or fainting. If he goes into am emotional state, he gets tachycardia. He shows hands and armpits oversweating. Mediastinal oppression and the lump in the throat happened. He has sudden colic at night, at 4-5 AM. No days of pallor nor eye sockets, no sudden asthenias were reported and no muscular hypertone in the morning. He is not an irritable person. There are no seasonal variations, except, perhaps, in winter. No symptoms of a schizophrenic psychosis appear.

Test therapy (daily doses, by the oral via): Glutamine 125mg; pyridoxine 75mg; carbamazepine 100mg; oxazepam 7.5mg; duhydroergotoxine 1.7mg.


First days of July 2004 (communication by teleohon): Perhaps some thing is moving, in the direction of a later daily onset of the cacosmia.

Therapt variation: Oxazepam 15 mg daily.


End July 2004: The first checkup after one month of drug therapy. He did not reach any result on the cacosmia/phantosmia. The time in which the trouble came out did not vary, and they happen between 7:00 AM and 2:00 PM. Once the cacosmia began at 8:00 PM, but this already happened in past. He did not have any tachycardia, mediastinal oppression, the lump on the throat, but much colic, either by night either by day. A bad dream occurred. Currently it is a period where he has emotionally troubles by his job. His hair did not change and his depressive mood too.

Therapy variation (daily doses, by the oral via): Pyridoxine, oxazepam, and dihydroergotoxine stopped. I prescribed glutamine 375mg; Carbamazepine 200mg; Bromazepam 0.75mg.

The patient did not come for the checkup and have to suppose that the therapy lasted only 33 days.



With the term of dysosmia we mean a distortion or a perversion of the sense of smell. It may operate with hyposmia or as solitary phenomenon. Dysosmia is then the general term, which includes the cacosmia, the phantosmia and the eterosmia.

From what the patient reported and here described, it seems that in this person we have to think to a double phenomenon. Some times it is an illusion (olfactory distortion or cacosmia) and some times a hallucination (olfactory irreality, the equivalent of a "dream" in the olfactory field or phantosmia).

We can exclude a peripheral olfactory problem, because not found and because in some moments the sense of smell works perfectly, to exclude too the result of a cranial trauma, because there was not any one. The fact that the distortion of the sense of smell disappears during a prolonged sleep, have driven towards a functional trouble.

Its long persistence during the day, after turning up, led similarly to exclude that it had anything to do with an epileptic equivalent.

Preceding EEGs never noticed something of anomalous. To think however to an unusual epileptic form was not absurd, for at least two reasons. The first one is the sudden inset of this phenomenon, which begins immediately to a maximum level.

The second one is that in certain epileptic forms of the right temporal lobe it was found an alteration of the sense of smell, even as an aura preceding the fit. (Kohler et al., 2001; Chen, Shih, Yen, and coll., 2003).

We had to swerve at once even the hypothesis of a brain tumour, not compatible with its long lasting (14 years ) of the olfactory trouble, without any worsening of the symptoms or onset of new symptoms. A schizophrenic psychosis (Kohler and coll., 2001) should be rejected because the patient has a personality and behaviour fully normal.

A share of altered brain circulation seemed probable in account of the manoeuvre of increasing the endocranial pressure of which the patient had "discovered" by himself the immediate suppressive efficacy, a kind of Valsalva's manoeuvre, as said his physician engaged woman.

In the end we may admit even some relationship with stress. During the first examination, following an emotional stress (a reproach because he did not respect an order), the daily cacosmia started, being not present till that moment.

I did a first hypothesis, complex and hardly verifiable. For possible circulatory reasons, the olfactory cortical region of the right half-brain did stop functioning, sometimes even as the following of an intense fragrant stimulus and so stressful, but not necessarily. Congenital circulatory alteration, possible of the rest (Toone, 1978), of little local arterioles, could have been the ground of this phenomenon. Cancelled the normal positive perception, and elicited a state of olfactory, sensory deprivation (Schulman, Richlin and Weinstein, 1967; Ziskind, Augsburg, 1967; Santoni, 1971), the right olfactory cortical area could have assumed negative perceptions recalled as only valid, for sustaining as active and, perhaps, for avoiding atrophy.

 It is a mechanism partly known (Cocchi, 2003 ), even if never applied to the cacosmia.

To have an olfactory hallucination, of course it needs owning to have memories in the "olfactory memory," which required a lot of time to be sedimented, to allow then evoking.

In this situation however it is the negative component (the bad odour) that substitutes the normal olfactory perception. It is hard to distinguish with safety between cacosmia and phantosmia.

This however was a coarse explanatory hypothesis that had to be integrated by many other data, to find enough validation.

A first therapeutic trial acting on stress and brain circulation did not give any result.

I proposed a second trial, by the hypothesis that it were a glutamate lacunar deficit, as the neurotransmitter of the afferent pathways, and then even of the olfactory ones olfattorie (Berkowicz, Trombley, e Shepherd, 1994; Duvoisin, Zhang e Ramonell, 1995). The disappearance of cacosmia during the sleep, where it is a saving of glutamate for reduced function of perceptions, does not oppose with this hypothesis. When cancelled the olfactory perception, the interpretation of what follows, should remain the same.

This second hypothesis was never verified because the patient did not come back for the checkup. Of other hand the idea of acting to improve the individual resistance (not in a homeopathic way or however in an "alternative" one) has a poor audience in the official Italian medicine.



Berkowicz, D.A., Trombley, P.Q. and Shepherd, G.M. Evidence for glutamate as the olfactory receptor cell neurotransmitter. J. Neurophysiol. 1994, 71, 2557-61.

Chen C, Shih YH, Yen DJ, et al. Olfactory auras in patients with temporal lobe epilepsy. Epilepsia (United States), 2003, 44: 257-260

Cocchi R. The phantom limb syndrome: A dream or a hallucination in brain areas deprived of somato-sensory inputs? (April 2004) <www.stress-cocchi.net/News14.htm>

Duvoisin RM, Zhang C and Ramonell K: A novel metabotropic glutamate receptor expressed in the retina and olfactory bulb. J. Neurosci. 1995, 15, 3075-3083.

Kohler CG, Moberg PJ, Gur RE, O'Connor MJ, Sperling MR, Doty RL. Olfactory dysfunction in schizophrenia and temporal lobe epilepsy. Neuropsychiatry Neuropsychol Behav Neurol. 2001, 14: 83-68.

Schulman CA, Richlin M, Weinstein S. Hallucinations and disturbances of affect, cognition, and physical state as a function of sensory deprivation. Percept Mot Skills (United States), 1967, 25: 1001-1024

Santoni C. Effetti psicologici della deprivazione sensoriale. Minerva Med. 1971, 62: 1282-1287.

Toone BK. Psychomotor seizures, arterio-venous malformation and the olfactory reference syndrome. A case report. Acta Psychiatr Scand. 1978, 58: 61-66.

Ziskind E, Augsburg T. Hallucinations insensory deprivation. (Method or madness?). Dis Nerv Syst (United States), Nov 1967, 28(11): 721-726.


Posted on Internet on 8 August 2005. Copyright by Renato Cocchi, 2005.


Author's address: dr. Renato COCCHI, via Rabbeno, 3

42100 Reggio Emilia

email: renatococchi@libero.it


Italian translation

Drug modulation of stress reactions

Anosmia, hyperosmia ecc.

Stress and depression

Home Page // Pagina iniziale