Neurology Case Challenge: Visual and Auditory Hallucinations in a Patient With Parkinson Disease

Lee Neilson, MD; Elena Cecilia Rosca, MD, PhD; Simu Mihaela, MD, PhD; Chirileanu Ruxanda Dana, MD, PhD


January 24, 2022


Dementia with Lewy bodies (DLB) was diagnosed based on the patient's history and the results of the neurologic and neuropsychologic examinations. The progression from delirium to frank parkinsonism to dementia shortly thereafter with episodes of altered mental status and visual and auditory hallucinations, is highly suggestive of the diagnosis.

DLB is the second most common neurodegenerative dementia after Alzheimer disease (AD), accounting for approximately 4.2% of dementia diagnoses in community settings and 7.5% of diagnoses in secondary care; however, these numbers are likely underestimates, as misdiagnosis is common.[1,2] It may present as a predominant dementia with some extrapyramidal signs or initially as parkinsonism with early-onset dementia, which is typically (although somewhat controversially) defined as dementia onset within 1 year.[3] Brief periods of confusion are present early in the disease course in a milieu of gradually worsening cognition, as well as impaired executive function and attention, with a tendency toward fluctuating cognitive performance. In fact, antecedent delirium increases the risk of progression to dementia, and evidence between delirium and DLB is mounting.[4]

The cognitive profile of a patient with DLB is typically early visuospatial impairment with rapid rate of decline; however, impairments in attention and executive function are also observed. Although memory function is less severe relative to AD, the rate of decline is similar.[5] Psychiatric symptoms are common. Hallucinations are prominent and rise to the level of a core clinical feature. The hallucinations tend to be visual but can occur in nonvisual modalities. Pareidolia, the perception of meaningful objects embedded visual scenes, is also characteristic of DLB.[6] Delusions, including delusional misidentification syndromes, are reported in as many as 50% of patients with DLB and may be an early finding.[7]

Currently, the definitive diagnosis of DLB rests on autopsy findings, with the presence of Lewy bodies situated in the substantia nigra and other brainstem nuclei (locus coeruleus, dorsal raphe, nucleus basalis of Meynert, dorsal motor nucleus of cranial nerve X) and the cerebral cortex (mainly in the amygdala and the entorhinal and anterior cingulate regions, but also in the neocortex).[8] Clinical diagnostic consensus criteria have, however, been developed for DLB.[9] The diagnosis of probable DLB requires a diagnosis of dementia in addition to 2 core features or 1 core feature and 1 indicative biomarker. Possible DLB can be diagnosed with either 1 core feature or indicative biomarker.

Core clinical features include the following:

  • Fluctuating cognition with pronounced variations in attention and alertness

  • Recurrent visual hallucinations

  • REM sleep behavior disorder (RBD)

  • Parkinsonism (presence of bradykinesia, rest tremor, or rigidity)

Indicative biomarkers include the following:

  • Reduced basal ganglia dopamine transporter uptake (single-photon emission computed tomography [SPECT] or positron-emission tomography [PET])

  • Abnormal (low uptake) 123iodine-MIBG myocardial scintigraphy

  • Polysomnographic confirmation of REM sleep without atonia

The cognitive fluctuations in DLB are deliriumlike, fluctuating from hour-to-hour and not perceived as "good days and bad days" nor a circadian phenomenon (ie, sundowning). RBD, in which the patient lashes out and shouts during vivid dreams, can often precede dementia by many years. Although comorbid posttraumatic stress disorder (PTSD) or concomitant use of selective serotonin reuptake inhibitors (SSRIs) may confound the ascertainment of true RBD, asking the question "Have you ever seen the patient appear to act out their dreams while sleeping?" can yield a positive predictive value of as high as 93%.[10]

Other supportive clinical features have been proposed. Although these lack diagnostic specificity, they are commonly present and may manifest early in the disease. These include the following:[11]

  • Severe sensitivity to antipsychotic agents

  • Postural instability

  • Repeated falls

  • Syncope or other transient episodes of unresponsiveness

  • Severe autonomic dysfunction (eg, constipation, orthostatic hypotension, urinary incontinence)

  • Hypersomnia

  • Hyposmia

  • Hallucinations in nonvisual modalities

  • Systematized delusions

  • Apathy

  • Anxiety

  • Depression

Occasional findings include supranuclear gaze palsy and myoclonus. Whereas the myoclonus of Parkinson disease is typically of small amplitude and may be confused with tremor, myoclonus in DLB can be of larger amplitude, more likely to occur at rest, and more prevalent.[12]

The current case fulfills the diagnostic criteria for probable DLB, with 3 core features.


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