Letters to the Editor
Sensory Deprivation and Disorders of Perception
Dear Editor:
Disorders of perceptions can be seen in schizophrenia, mania, delirium, metabolic and endocrinal disorders, epilepsy, brain tumors and drug intoxication, or by direct effects of some drugs (for example, hallucinogens). They can also be seen in the electrical stimulus of structures such as the amygdale and temporal cortex and in other pathologies of the brain (1). Perceptual disorders can also be observed, except for brain pathology or psychopathology. In these cases, it is largely suggested that the reason for perceptual disorders is sensory deprivation. Even though the mechanism is not well known, it is believed to be similar to phantom extremity phenomenon (2).
In the literature, there are articles about visual hallucinations observed in patients having visual defects without suffering from any psychiatric disorder (2–6). This was first claimed by Charles Bonnet, a Swiss scientist. Bonnet’s grandfather experienced live visual hallucinations at age 89 years, 11 years after having cataract surgery (3). Interestingly, Bonnet himself suffered from visual defects and afterward had similar symptoms. Morisier first named this Charles Bonnet Syndrome (CBS) in 1938 (4). Once the syndrome was named, many similar cases were reported, and diagnostic criteria were developed for CBS (5,6). In this article, we report on the case of a patient with auditory hallucinations in the left ear only. The patient has suffered from hearing loss in the left ear for 5 years, but has not used a hearing and for the last 2 years.
Case Report
A woman, aged 63 years, complained that she was hearing voices for the past 1½ to 2 years and that the voices had increased in the last month, especially at night. At first, she was afraid of the voices and thought she was mad; then she realized they were not real. She had hearing loss in her left ear following a car accident 5 years ago, and it was recommended that she use a hearing aid. Since the aid disturbed her ear, she used it irregularly for 3 years and not at all thereafter. Five to 6 months later, she started to hear voices. Everything was normal in the patient’s psychiatric examination except for auditory hallucinations and anxious mood. There was no substance use or psychiatric illness in her history. Complete blood count, biochemical tests, thyroid function test, EEG, cranial computed tomography scan, and neurological examinations of the patient were normal. Her score on the Mini-Mental State Exam was 27. The Minnesota Multiphasic Personality Inventory and Beier Sentence Completion tests were evaluated as normal. Treatment was started with olanzapine 10 mg daily and diazepam 10 mg daily. Later, diazepam was stopped and continued by olanzapine 5 mg daily only. On the tenth day of treatment, the auditory hallucinations disappeared. The patient was observed for 10 months at regular intervals; she took olanzapine 5 mg daily and used a hearing aid for 7 months. During this time, no psychopathology had been detected.
How could sensory deprivation cause disorders of perception? Even though the mechanism is not well known, it is believed to work similarly to phantom extremity phenomenon. In phantom extremity phenomenon, the sensory deprivation could be due to amputation of a body part, damage of the sensory nerve, brachial plexus, or blockage of the spinal cord by anesthetic agent (2). In this case report, the sensory deprivation now caused by damage to the auditory ways after an accident. In both cases, the stimuli going to the cortex were blocked. However, how the perceptual disorders occur is still not known. Perhaps the hallucinations are due to receptor hypersensitivity. This could be explained by examining the effective mechanisms of hallucinogens and atypical antipsychotics. Hallucinogens and serotonin-dopamine antagonists (SDAs) act through the same receptors but create different effects. Hallucinogens activate 5HT2A, 5HT2C, and 5HT6 receptors and cause hallucinations. In contrast, SDAs block these receptors and prevent the formation of hallucinations (9).
Could this patient be diagnosed with CBS? For now, the diagnosis criteria for CBS defined by various authors are as follows: The patient should have complex visual hallucinations; insight should be partially or totally protected (that is, hallucinations should be perceived as unreal); there should not be delirium, and there should not be hallucinations in the other sensory organs (5,6). Our patient perceived the hallucinations as unreal and did not have delirium, but she could not be diagnosed with CBS because these criteria focus only on visual hallucinations. At this point the purpose is to possibly prevent discarding the diagnosis of not otherwise specified psychotic disorder, since auditory hallucinations are the most often observed perceptual disorders in schizophrenia. However, the patient’s psychiatric examination and psychometric evaluation proved she had no psychosis. Further, auditory hallucinations were only in the ear with hearing loss, and our patient perceived these as unreal. In the literature, CBS cases with auditory hallucinations and auditory hallucinations in deaf patients have rarely been mentioned (7,8,10,11). Thus, according to us, the diagnosis of this patient was CBS. Within this context, we suggest that the diagnostic criteria of CBS could be enhanced. Additionally, if it could be proven that the patient did not suffer from psychosis and other perceptual disorders, except from visual hallucinations that could be seen in the other sensory organs with sensory deprivation, the diagnosis could again be CBS.
References:
1. Elkin GD. Introduction to clinical psychiatry. 1st ed. Stamford: Appleton & Lange; 1999. p 8.
2. Schultz G, Melzack R. The Charles Bonnet Syndrome: ‘phantom visual images’. Perception 1991;20:809–25.
3. Damas-Mora J, Skelton-Robinson M, Jenner FA. The Charles Bonnet Syndrome in perspective. Psychol Med 1982;12:251–61.
4. Morisier G de. Les hallucinations. Rev Otoneuroophthalmol 1938;16:244–352.
5. Teunisse RJ, Cruysberg JR, Hoefnagels WH, Verbeek AL, Zitman FG. Visual hallucinations in psychologically normal people: Charles Bonnet’s Syndrome. Lancet 1996;347:794–7.
6. Gold K, Rabins PV. Isolated visual hallucinations and the Charles Bonnet Syndrome: a review of the literature and presentation of six cases. Compr Psychiatry 1989;30:90–8.
7. Raghuram R, Keshavan MD, Channabasavanna SM. Musical hallucinations in a deaf middle-aged patient. J Clin Psychiatry 1980;41:357.
8. Miller TC, Crosby TW. Musical hallucinations in a deaf elderly patient. Ann Neurol 1979;5:301–2.
9. Kaplan HI, Sadock BJ. Kaplan & Sadock’s Comprehensive Textbook of Psychiatry. Vol I. 7th ed. New York: Williams & Wilkins; 2000. p 46.
10. Patel HC, Keshavan MS, Martin S. A case of Charles Bonnet Syndrome with musical hallucinations. Can J Psychiatry 1987;32:303–4.
11. Hori H, Terao T, Nakamura J. Charles Bonnet Syndrome with auditory hallucinations: a diagnostic dilemma. Psychopathology 2001;34:164–5.
Fatih Volkan Yuksel, MD,
Cebrail Kisa, MD, Cigdem Aydemir, MD,
Erol Goka, MD
Ankara, Turkey
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