Monosymptomatic Delusions of Parasitosis Associated With Ischemic Cerebrovascular Disease Frederick G. Flynn, DO, LTC, MC; Jeffrey L. Cummings, MD; Joan Scheibel, MD, PhD; William Wirshing, MD Abstract Monosymptomatic delusions of infestation (parasitosis) occur in idiopathic psychoses but have rarely been observed in patients with neurologic or systemic illnesses. A patient was observed in whom the delusion occurred in the presence of demonstrable cerebrovascular disease. The delusional symptoms were contralateral to the principal site of ischemic injury. Delusions of infestation may reflect an acquired neurologic or metabolic disorder, and medical and neurologic evaluation should be pursued in elderly patients presenting with this syndrome. ( J Geriatr Psychiatry Neurol 1989;2:134-139). he delusion of parasitic infestation is the unTshakable but false belief that one’s body or a part of one’s body is inhabited by insects or worms. This belief is held firmly despite substantial evidence to the contrary. The body part most often affected is the skin. Thieblergel coined the term &dquo;acarophobian to de. scribe this condition. Ekbom2 criticized this name because patients with the delusion are not fearful of being infested prior to the onset of the delusion, and thus the syndrome lacks the defining characteristic of phobic disorders. The term HparasitophobiaH coined by Goldsmith and Hellier3 can be criticized for the same reason. Munro4 included the three syndromes of delusional infestation, bromosis, and dysmorphosis as forms of monosymptomatic hypochondriacal psychosis. Bromosis, or olfactory reference syndrome, is the delusion Received July 31, 1989. Accepted for publication August 17, 1989. From the Neurobehavior Unit (Drs Flynn and Cummings) and Psychiatry Service (Drs Cummings, Scheibel, and Wirshing), West Los Angeles Veterans Administration Medical Center; Departments of Neurology (Drs Flynn and Cummings) and Psychiatry & Biobehavioral Sciences (Drs Cummings, Scheibel, and Wirshing), UCLA School of Medicine, Los Angeles, CA; and US Army AMEDD Student Detachment Academy of Health Sciences (Dr Flynn), Ft Sam Houston, TX. Military disclaimer: The views of the authors are their own and do not purport to reflect the position of the Department of the Army or the Department of Defense. Address correspondence to Dr Cummings, Neurobehavior Unit (B111), Ward 256a, Brentwood VA Medical Center, 11301 Wilshire Blvd, Los Angeles, CA 90073. of foul odors emanating from one’s body, and dysmorphosis refers to the delusion of misshapen body parts or disfigurement. Currently, these three conditions are encompassed within the syndrome of Delusional (Paranoid) Disorder-Somatic Type in the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R).5 Monosymptomatic delusions of parasitosis can occasionally occur in disorders other than pure paranoid syndromes. Wilson and Miller6 recognized that there was considerable diversity in the etiology of the parasitic infestation delusion despite the phenomenologic homogeneity of the symptoms. They divided their patients into four etiologic categories: toxic psychoses, schizophrenia, involutional melancholia, and paranoid disorder. The toxic etiologies included pneumonia, cardiac decompensation, and drug intoxication, particularly with ethanol and central nervous system stimulants. Toxic patients often manifested acute confusion, and treatment of the underlying condition often resulted in resolution of the delusions .7 Schizophrenic patients, manifested features characteristic of schizophrenia (eg, other delusions, formal thought disorder) in addition to the delusion of infestation. The melancholic form had associated depressive symptoms that were more dominant than the delusional symptom, and treatment of the depression often ameliorated the delusion. The paranoid type was the class most likely to manifest the monosymptomatic delusion of infestation exclusive of other psychiatric symptomatology. It usu- 134 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015 ally occurred in the elderly, and over 70% of affected patients were male.66 Hopkinsong also noted the etiologic heterogeneity of the delusion of infestation and subdivided the causes into the following categories: bipolar mood disorder, in- duced delusions, chronic tactile hallucinosis secondary to toxins, tactile hallucinosis associated with vascular disease, other organic brain diseases, schizophrenia, and personality disorders. Skott9 reviewed over 70 cases of delusions of parasitic infestation and recorded the following organic etiologies: toxins, primary central nervous system neoplasms, hypothyroidism, diabetes mellitus, cardiovascular disease, polycythemia vera, vitamin B12 deficiency, anticholinergic agents, monoamine oxidase inhibitors, amphetamines, cocaine, methylphenidate, and delirium tremors. Miller et allo recently reported a patient with delusional infestation associated with normal pressure hydrocephalus. Other specific organic causes of delusional parasitosis have included alcoholism, syphilis, &dquo;arteriosclerosis,&dquo; and &dquo;senility.&dquo; We report an elderly patient who presented with the recent onset of the monosymptomatic delusion of parasitic infestation secondary to cerebral ischemic changes. The temporal association between the delusional disorder and the ischemic injury was more apparent than in previously reported cases, and there was a unique association between the laterality of the lesion and the side of the perceived infestation. Case Description A 67-year-old, right-handed male, presented with a complaint of crawling sensations beneath the skin of his left ear. The patient believed that these sensations were due to worms inhabiting the region. This somatic sensation was often accompanied by a buzzing sound that he attributed to the migratory movement of the worms. This migration usually occurred beneath the left scalp. Hospitalization was pursued when his wife discovered him picking at his scalp with tweezers in an attempt to extirpate the &dquo;worms.&dquo; The patient was unswervingly convinced that worms occupied his scalp, and insisted on further medical evaluation to verify their presence. The sensation of migration of the worms was confined principally to the left side of the scalp. There was infrequent movement from the scalp to the left arm and leg. The patient was convinced that on one occasion a female worm had given birth to several baby worms. The patient had no other delusions, hallucinations, thought disorder, or mood disturbance. The right side of the body was not involved in the ’ delusion. There was a past medical history of moderate hypertension, coronary artery disease, an anterior wall myocardial infarction, and repeated episodes of right eye amaurosis fugax. The last episode of temporary blindness had occurred within one month of the onset of the patient’s delusion. The patient also had a 40 pack-year history of smoking, and he had drunk one to two alcoholic beverages a day for many years; he had stopped smoking and drinking several years prior to hospitalization. The patient’s medical regimen included atenolol, 100 mg per day, and transderm-nitroglycerin patches, 5 mg twice daily. The patient had completed the llth grade, and had worked as a custodian and locksmith until his retirement at age 65 years. There was no prior history of psychiatric illness. Neurologic examination demonstrated mild impairment of fine motor coordination, slightly bradykinetic gait, mildly increased muscle tone, and symmetrically brisk muscle stretch reflexes. Cranial nerves, strength, sensation, and gross motor function were all intact, and plantar responses were flexor. He had bilateral carotid bruits, and grade II/VI aortic stenotic and mitral regurgitation murmurs. There was no evidence of dermatologic disease of the scalp. Mental status testing revealed the patient to be oriented to self, location, date, and time. Mini-mental state examinationll score was 25 out of a total possible score of 30. He could repeat six digits forward and four backwards. Language comprehension, repetition, fluency, and naming were intact. He was able to produce 11 animal names in 1 minute. Memory testing demonstrated intact registration, but he was able to spontaneously recall only two of eight words after a 10-minute interval. The remaining six words were recalled with category cues. He was able to copy simple figures accurately and made only minor errors when copying complex models. Addition, subtraction, and multiplication problems were performed well. Idiom interpretation was concrete. There was no apraxia, and frontal systems tasks performed normally. Laboratory evaluations including complete blood count, electrolytes, blood urea nitrogen, creatinine, serum vitamin B12 and folate levels, thyroid function tests, serum iron and iron binding capacity, and toxin and heavy metal screens were all within normal limits. VDRL test was nonreactive. An audiogram revealed bilateral high-frequency sensory-neural hearing loss with more impairment in the left ear. Electrocardiogram showed no pathologic changes. An echocardiogram demonstrated an organized left ventricular mural thrombus. Electroencephalography was within normal limits. Computed tomography (CT) of the brain revealed hypodense bilateral periventricular lesions and a were 135 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015 hypodense area in the right splenial area (Figure 1). Magnetic resonance imaging (MRI) demonstrated bilateral high-signal periventricular lesions and circumscribed high-signal lesions in the right subcortical frontal area and the right side of the splenium of the corpus callosum (Figure 2). During the hospital stay, the patient’s mood became depressed, and he manifested insomnia, weight loss, anergia, and passive suicidal ideation. The monosymptomatic delusion of worm infestation persisted unchanged. A trial of amitriptyline resulted in ischemic changes on electrocardiogram, and trazadone produced painful priapism. Trials of various neuroleptic agents including haloperidol, chlorpromazine, trifluoperazine, and thiothixene failed to ameliorate the delusion. Molindone produced limited resolution of the delusion, but severe akathisia required discontinuation of the drug. The patient’s mood disorder resolved and his akathisia improved after a combination of thiothixene, nortriptyline, and diphenhydramine was administered. The monosymptomatic delusion of infestation persisted. The patient left the hospital against medical advice but resumed outpatient follow-up. He had discontinued all psychotropic medications. The delusion remained and was highly disturbing to the patient, and a trial of amoxapine was initiated. Although the delusion persisted, the patient was less distressed and better able to function in his daily life. Discussion The patient presented in this report exhibited delusional infestation. A careful dermatologic evaluation excluded an actual parasitosis and the illogical and delusional nature of the complaints was evident with long-term observation. The differential diagnosis of the syndrome included organic delusional disorder secondary to cerebrovascular disease, psychotic depression with monosymptomatic hypochondriacal psychosis, and alcohol-related brain dysfunction with psychosis. Organic delusional disorder was supported by the late onset of the disorder, presence of cerebrovascular risk factors, the temporal relationship of signs of ischemia to the onset of the delusion, and the identification of evidence of cerebral ischemic injury. The lesions seen on MRI were more extensive than the age-related changes that may be visualized in the elderly. Depression as an etiology of the delusion was rendered unlikely by the appearance of the delusion prior to evidence of a mood disorder, failure to change with antidepressant medication, and persistence after the mood disturbance resolved. An alcohol-related neuropsychiatric syndrome was considered unlikely since the patient had been abstinent for many years prior to the occurrence of the delusional disorder and had no prior _ psychotic symptoms. ... FIGURE 1 CT scan demonstrating periventricular lucencies consistent with cerebral ischemic injury. One lucent area extends into the splenium of the corpus callosum on the right. ’ The association between delusional syndromes and organic central nervous system disease has been the subject of several recent studies. Miller et a11° and Cummings 12 observed an association of cerebrovascular disease with late-onset delusions. Cummings and colleaguesl3 demonstrated late-onset delusions in up to 40% of patients with multi-infarct dementia. In previously reported cases, the delusions have been persecutory in nature, involving the threat of personal harm, theft of property, or marital infidelity.l2 Contentspecific delusions involving Capgras’s syndrome (the belief that someone has been replaced by an identicalappearing imposter) and phantom boarder syndrome (the belief that an uninvited guest lives in one’s household) have also been observed. 12 Previous authors have cited &dquo;arteriosclerosis&dquo; as an underlying etiology for the delusion of parasitic infestation. 2,4,6,14 These patients had various combinations of hypertension, diabetes, and heart disease, but no clinically reported evidence of stroke. Valbuena Briones et a115 described a patient with a cerebral infarction who developed the syndrome within a few months of the stroke. This patient had also developed 136 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015 . FIGURE 2A FIGURE 2C FIGURE 2B FIGURE 2 A. MRI scan demonstrating periventricular and right subcortical frontal and fronto-parietal high-signal lesions consistent with ischemic damage. B. MRI scan demonstrating high-signal periventricular capping, as well as a right subcortical frontal lesion. C. High-signal lesions can be seen in the right subcortical frontal and splenial regions. ’ an intercostal herpes zoster infection. The parasitic delusion was localized to the area surrounding the infection. Berriosl6 reported a patient with delusional infestation and an electroencephalogram interpreted as compatible with cerebrovascular disease, however the patient had no clinical features or neuroimaging evidence corroborating the presence of cerebrovascular disease. Bauer and Mosler17 described a patient with dementia, depression, and delusional infestation ascribed to arteriosclerotic disease. Miller and Lesserl$ documented a 20% incidence of silent vascular disease in patients with late-life paraphrenia using MRI. The present case is unique in that the timing of the onset of the delusion, the focal nature of the symptoms, and the MRI scan results all support the postulation of underlying cerebral ischemic disease as the principal etiologic factor. Delusions may occur with lesions of either the left or right hemisphere. Levine and Finkelsteinl9 reported the occurrence of delayed psychoses in patients who had sustained right temporal-parietal strokes or trauma. Peroutka et a12° reported hallucinations and delusions following a right temporal-parietal-occipital infarction. Other monosymptomatic delusions such as Capgras’s syndrome often occur as a result of right hemisphere dysfunction.21-24 Left temporo-parietal infarction may also be associated with delusions. 13 Signer et a125 recently observed that delusions were the most common psychiatric disorder in patients with chronic aphasic disorders requiring psychiatric hospitalization. In this study, delusions were more closely associated with posterior than anterior lesions of the left hemisphere. Specific central nervous system changes unique to monosymptomatic delusions or to delusions of infestation have not been observed, but a majority of patients have had lesions of the subcortical structures of the brain. Southard26 observed a patient with delusions of bees inside her head who exhibited metastatic involvement of the pituitary gland at autopsy; Liebaldt and Klages (reported by Hopkinson8) described a patient with a chromophobe adenoma producing extensive destruction of the midbrain and posterior hypothalamus; Bernosl6 reported a patient with onset of delusional infestation coinciding with infarction of a pituitary tumor; and Heim and Morgner 27 noted atrophy of the brain stem and thalamus in two patients with delusions of infestation. Schott et a128 described two sisters with the delusion and evidence of subcortical atrophy on pneumoencephalography; and McGowan and Cook29 observed the syndrome in a patient following encephalitis lethargica. A number of patients with dementia, presumably of the Alzheimer type, and delusional infestation have also been described. 17,30,31 The latter have extensive changes in the neocortical association areas, medial temporal archicortex, and the limbic sys- 137 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015 tem including the posterior cingulate and amygdala. 32 Thus, patients with delusional parasitosis share with other patients with organic delusional disorders a comtopography of lesions involving the subcortical and limbic brain areas. 12 The delusional symptoms in this case were almost entirely confined to the left side of the body, and the patient’s neurological symptoms (amaurosis fugax) and MRI and CT changes reflected abnormalities primarily on the right side of the brain. Similar spatially restricted delusions have rarely been observed previously. Critchley33 described a patient with a right parietal lesion who experienced paranoid fear only for objects on his left. Several important interactions between existing somatic conditions and delusions of parasitosis have been observed. In some cases, the disorder may have its onset following the successful treatment of an actual infection. Wilson and Miller6 reported patients previously infected with syphilis or leprosy who developed delusions after successful therapy of the underlying disorder. In other cases, the delusion was specifically focused in a body region that had previously sustained injury. Weidner34 reported a patient who developed delusional parasitosis of a leg that had been fractured 35 years previously, and EkbOM2 reported an individual whose delusion affected a previously injured region of the scapula. Similarly, hearing loss provides abnormal sensory input and has been found by some investigators to be a risk factor for the occurrence of late-life delusions. 35-37 The current patient experienced tinnitus and hearing loss, and these aberrant sensations appeared to contribute to his delusion. The initial intervention in monosymptomatic delusions of parasitic infestation associated with organic disorders should be directed at identifying and treating the underlying illness. In many cases, treatment directed at the delusion itself will also be needed. Wilson and Miller6 described the treatment prognosis of their patients as almost hopeless,&dquo; with 82% of patients remaining unchanged. Before the development of neuroleptics, insulin shock therapy was used in selected patients with this syndrome with little success6 Electroconvulsive therapy has infrequently been used in the syndrome but has usually been ineffective in ameliorating the delusional symptoms.l6 Recently, the use of neuroleptic and antidepressant agents has helped to resolve the syndrome. Haloperidol,38 doxepin, imipramine,39 nortriptyline,4° and monoamine oxidase inhibitors 14 have all been tried with varying degrees of benefit. Pimozide has had the most predictable success in relieving the symptoms of monosymptomatic delusion of parasitic infestation. 30,41-46 Munro mon and Chmara44 reported improvement in 82% of their patients treated with pimozide. Delusional parasitosis is a rare syndrome. Retterstol47 reported a prevalence of 0.4% of hypochondriacal psychoses among 3,441 psychiatric patients, and Heim and Morgner 27 described a prevalence of 0.09% of delusional infestation. The syndrome has particular importance, however, in that as many as 50% of patients with delusions of parasitosis will be found to be suffering from organic mental disorders,3° and the per- centage may rise as more sophisticated assessment technologies gain widespread application. Thus, a-diagnostic evaluation of elderly patients presenting with monosymptomatic delusions of parasitosis is war- ranted, and many can be expected to be suffering from cerebrovascular disease. References 1. Thieblerge G: Les acarophobes. Rev Gen Clin Ther 1894; 32:373. 2. Ekbom KA: Der präsenile Dermatozoenwahn. Acta Psychiatr Neurol 1938;3:227-259. 3. Goldsmith WN, Hellier, FF: Recent Advances in Dermatology. London, JV Churchill, 1954. 4. Munro A: Monosymptomatic hypochondriacal psychoses. Can Psychiatr Assoc J 1978;23:497-500. 5. Diagnostic and Statistical Manual of Mental Disorders, ed 3. Washington, DC, American Psychiatric Association, 1987. 6. Wilson JW, Miller HE: Delusion of parasitosis. Arch Dermatol Syph 1946;54:39-56. 7. Wilson JW: Delusion of parasitosis (acarophobia). Arch Dermatol Syph 1952;66:577-585. 8. Hopkinson G: The psychiatric syndrome of infestation. Psychiatr Clin 1973;6:330-345. 9. Skott A: Delusions of infestation, in St Jorgen Hospital: Report From the Psychiatric Research Center. Göteborg, University of Göteborg, 1978. 10. Miller BL, Benson DF, Cummings JL, et al: Late-life paraphrenia: An organic delusional syndrome. J Clin Psychiatry 1986; 47:204-207. 11. Folstein MF, Folstein SE, McHugh PR: "Mini-mental state": A practical method for grading the mental state of patients for the Res 1975;12:189-198. clinician. J 12. Cummings JL: Organic psychosis. Psychosomatics 1988; 29:16-26. 13. Cummings JL, Miller B, Hill MA, et al: Neuropsychiatric aspects of multi-infarct dementia and dementia of the Alzheimer type. Psychiatr Arch Neurol 1987;44:389-393. 14. Bishop ER: Monosymptomatic hypochondriacal syndromes in dermatology. J Am Acad Dermatol 1983;9:152-158. 15. Valbuena Briones A, Avila Escribano J, de Dios Perrino C, et al: Delirio dermatozoico (parasitario). Med Clin (Barc) 1984;83: 249-252. 16. Berrios GE: Delusional parasitosis and physical disease. Comp Psychiatry 1985;26:395-403. 17. Bauer VA, Mosler A: Die Behandlung des Dermatozoenwahnes. Arzneimittelforsch 1970;20:884-886. 18. Miller BL, Lesser IM: Late-life psychosis and modern neuroimaging. Psychiatr Clin North Am 1988;11:33-46. 138 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015 19. Levine DN, Finkelstein S: Delayed psychosis after right temporoparietal stroke or trauma: Relation to epilepsy. Neurol- ogy 1982;32:267-273. 20. Peroutka SJ, Sohmer BH, Kumer AJ, et al: Hallucinations and delusions following a right temporoparieto-occipital infarction. Johns Hopkins Med1982;151:181-185. 21. Alexander MP, Stuss DT, Benson DF: Capgras syndrome: A redu- plicative phenomenon. Neurology 1979;29:334-339. 22. Hayman MA, Abrams R: Capgras’ syndrome and cerebral dysfunction. Br J Psychiatry 1977;130:68-71. 23. Joseph AB: Focal central nervous system abnormalities in patients with misidentification syndromes, in Christodoulou GN (ed): The Delusional Misidentification Syndromes. New York, Karger, 1986. 24. Wilcox JA: The anatomical basis of misidentification, in Christodoulou GN (ed): The Delusional Misidentification Syndromes. New York, Karger, 1986. 25. Signer S, Cummings JL, Benson DF: Delusions and mood disorders in patients with chronic aphasia. J Neuropsychiatry Clin Neurosci 1989;1:40-45. 26. Southard EE: On the somatic sources of somatic delusions. J Abnorm Psychol 1912;7:326-339. 27. Heim M, Morgner J: Zur Problematik der chronischen taktilen Halluzinose. Psychiatr Neurol Med Psychol 1980;32:405-411. 28. Schott G, Marg E, Elsaber H: Uber eine familiare Erkrankung anchronischer taktiler Halluzinose. Psychiatr Neurol Med Psychol 1973;25:599-605. 29. McGowan PK, Cook LC: The mental aspect of chronic epidemic encephalitis. Lancet 1928;1:1316-1320. 30. Hamann K, Avnstorp C: Delusions of infestation treated with pimozide: A double-blind crossover clinical study. Acta Dermatovener 1982;62:55-58. 31. Renvoize EB, Kent J, Klar HM: Delusional infestation and dementia : A case report. Br J Psychiatry 1987;150:403-405. 32. Brun A, Gustafson L: Limbic lobe involvement in presenile dementia. Arch Psychiatr Nervenkr 1978;226:79-93. 33. Critchley M: The Parietal Lobes. New York, Hafner Publishing, Ungezieferwahnes. 34. Weidner H: Beitragë zur Kasuistik des Munchen Med Wochnschr 1936;83:1920-1921. 35. Christenson R, Blazer D: Epidemiology of persecutory ideation in an elderly population in the community. Am J Psychiatry 1984;141:1088-1091. 36. Kay DW, Cooper AF, Garside RF, et al: The differentiation of paranoid from affective psychoses by patients’ premorbid characteristics. Br J Psychiatry 1976;129:207-215. 37. Post F: Persistent Persecutory States of the Elderly. Oxford, Pergamon Press, 1966. 38. Andrews E, Bellard J, Walter-Ryan WG: Monosymptomatic hypochondriacal psychosis manifesting as delusions of infestation : Case studies of treatment with haloperidol. J Clin Psychiatry 1986;47:188-190. 39. Brotman AW, Jenike MA: Monosymptomatic hypochondriasis treated with tricyclic antidepressants. Am J Psychiatry 1984; 141:1608-1609. 40. Pylko T, Sicignan J: Nortriptyline in the treatment of a monosymptomatic delusion. Am J Psychiatry 1985;142:1223. 41. Riding BE, Munro A: Pimozide in monosymptomatic psychosis. Lancet 1975;1:400. 42. Reilly TM: Pimozide in monosymptomatic psychosis. Lancet 1975;1:1385-1386. 43. Munro A, Pollack B: Monosymptomatic psychoses which pro- gress to schizophrenia. J Clin Psychiatry 1981;42:474-476. 44. Munro A, Chmara J: Monosymptomatic hypochondriacal psychoses : A diagnostic checklist based on 50 cases of the disorder. CanJ Psychiatry 1982;27:374-376. 45. Duke EE: Clinical experience with pimozide: Emphasis on its use in post herpetic neuralgia. J Am Acad Dermatol 1983; 8:845-850. 46. Lindskov R, Baadsgaard O: Delusions of infestation treated with pimozide: A follow-up study. Acta Derm Venereol 1985; 65:267-270. 47. Retterstol N: Paranoid psychoses with hypochondriac delusions as the main delusion. Acta Psychiatr Scand 1968;44:334-353. 1953. 139 Downloaded from jgp.sagepub.com at CARLETON UNIV on June 26, 2015