OBSERVATION Dementia With Lewy Bodies Studied With Positron Emission Tomography Rebecca J. Cordery, BSc, MRCP; Philippa J. Tyrrell, MD, FRCP; Peter L. Lantos, MD, PhD, DSc, FRCPath; Martin N. Rossor, MD, FRCP Objective: To report a case initially fulfilling the clini- Results: Oxygen 15–labeled positron emission tomo- cal criteria for probable Alzheimer disease, although later grams revealed hypometabolism in the frontal, tempo- clinical features suggested dementia with Lewy bodies. ral, and parietal lobes, more severe on the left than right. Oxygen 15–labeled positron emission tomograms re- Metabolism in the left caudate was just outside the 95% vealed a pattern of hypometabolism characteristic of Alz- reference range. Occipital metabolism was normal. heimer disease. At post mortem, there was no evidence of the pathological features of Alzheimer disease, but dif- Conclusions: Positron emission tomographic studies fuse cortical Lewy bodies were seen in the pigmented have been reported to show occipital hypometabolism brainstem nuclei and cerebral cortex. in dementia with Lewy bodies, in addition to the char- acteristic posterior bitemporal biparietal pattern of Alz- Design: A case report. heimer disease. We suggest that although this finding may favor a diagnosis of dementia with Lewy bodies, it is not Setting: Tertiary referral center. necessary for diagnosis. Patient: A 65-year-old white man presented with a 3-year history of memory loss and language difficulties. Arch Neurol. 2001;58:505-508 LTHOUGH CRITERIA for bonethoxy-3b-(4-iodophenyl)-N-(3-fluo- clinical diagnosis may aid ropropyl)nortropane (a dopaminergic the distinction between presynaptic ligand) and single photon Alzheimer disease (AD) emission computed tomography can be (International Classifica- used to assess nigrostriatal pathway integ- Ation of Diseases, 10th Revision, Diagnostic rity in vivo.8 Preliminary results, though in- and Statistical Manual of Mental Disor- conclusive, suggest that it may be possible ders, Fourth Edition, and National Insti- to distinguish DLBs and AD by the ab- tute Neurological Communicative Disor- sence of nigrostiatal degeneration in the lat- ders and Stroke–Alzheimer’s Disease and ter. Positron emission tomographic stud- Related Disorders Association) and de- ies have shown occipital hypometabolism mentia with Lewy bodies (DLBs),1,2 diag- in DLBs in addition to the characteristic pos- nosis may be difficult, particularly early in terior bitemporal biparietal pattern of AD,9-12 the course of the disease. Thus, although but thus far have not contributed to estab- a parkinsonian syndrome is one distin- lishing the differential diagnosis of DLBs From the Dementia Research Group, Department of Clinical guishing feature of DLBs, a proportion of and AD. Elderly patients with late-life de- Neurology, Institute of patients with dementia of the Alzheimer pression may have a widespread, nonfocal Neurology and Division of type may also have extrapyramidal signs pattern of reduction in glucose metabo- Neurosciences, Imperial College in the absence of Lewy bodies that are at- lism similar to that seen in patients with School of Medicine tributable to extranigral factors.3,4 AD,13 a finding that may further compli- (Drs Cordery and Rossor), the Neuroimaging may contribute to the cate the diagnosis. Medical Research Council differential diagnosis. Alzheimer disease Cyclotron Unit, Hammersmith is characteristically associated with atro- REPORT OF A CASE Hospital (Dr Tyrrell), and the phy of medial temporal lobe structures on Department of Neuropathology, magnetic resonance images or computed A 65-year-old retired businessman pre- Institute of Psychiatry tomograms, but this atrophy is also seen sented in May 1988 with a 3-year history (Dr Lantos), London, England. 5-7 Dr Tyrrell is now with the to a lesser extent in patients with DLBs. of memory loss and language difficulties. Department of Geriatric It is therefore suggested that it is the ab- He stated that he had trouble finding both Medicine, Hope Hospital, sence of medial temporal atrophy that is spoken and written words, as well as dif- Salford, England. highly suggestive of DLBs. [123I]-2b-car- ficulty with reading, comprehension, and (REPRINTED) ARCH NEUROL / VOL 58, MAR 2001 WWW.ARCHNEUROL.COM 505 ©2001 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 memory test for words.14 His speed of information pro- Regional Cerebral Metabolic Rates for Oxygen (CMRO2) cessing was impaired on a cancellation task and on a simple digit copying test. In contrast, he scored within −1 −1 CMRO2,mL·min ·dL the average range on tests of naming and object percep- Region Patient Normal* tion. Overall, the pattern was that of a generalized de- Left superior frontal gyrus 1.67 3.08 ± 0.34 cline in intellectual and memory functions. Right superior frontal gyrus 2.29 3.12 ± 0.33 The results of all baseline investigations were nor- Left middle frontal gyrus 1.94 2.92 ± 0.30 mal. On an electroencephalogram, the dominant rhythm Right middle frontal gyrus 2.39 2.91 ± 0.29 was slow and quite widespread, with little attenuation Left inferior frontal gyrus 1.83 2.98 ± 0.29 with eye opening. There were episodes of slow waves Right inferior frontal gyrus 2.51 3.04 ± 0.32 throughout, predominantly anteriorly, which were some- Left cingulate gyrus 2.69 3.42 ± 0.58 Right cingulate gyrus 2.69 3.52 ± 0.62 times independent but more often were present as a gen- Left superior temporal gyrus 2.13 2.96 ± 0.25 eralized disturbance. A computed tomographic scan of Right superior temporal gyrus 3.01 3.13 ± 0.41 the brain revealed no abnormalities. Left middle temporal gyrus 1.78 3.12 ± 0.33 An oxygen 15–labeled PET scan was performed (CTI Right middle temporal gyrus 1.95 3.12 ± 0.17 931-08/12 camera; Computed Technology and Imaging Left inferior temporal gyrus 2.00 3.18 ± 0.21 Inc, Knoxville, Tenn) at the Medical Research Council Right inferior temporal gyrus 2.66 3.15 ± 0.37 Left postcentral gyrus 2.05 2.99 ± 0.15 Cyclotron Unit (Hammersmith Hospital, London, Right postcentral gyrus 2.33 3.07 ± 0.30 England). The performance characteristics of this scan- Left inferior parietal lobe 2.11 3.11 ± 0.17 ner and the practical procedure have been previously de- Right inferior parietal lobe 2.71 3.09 ± 0.25 scribed.4,15 An oxygen 15–labeled steady-state inhala- Left superior parietal lobe 1.98 3.08 ± 0.28 tional technique was used with calculation of the regional Right superior parietal lobe 2.43 3.15 ± 0.22 16,17 cerebral metabolic rate for oxygen (CMRO2 ). A se- Left thalamus 3.22 3.57 ± 0.42 ries of parametric images of CMRO were computed. Ana- Right thalamus 3.03 3.73 ± 0.52 2 Left caudate nucleus 2.96 3.77 ± 0.39 tomically correct regions of interest were placed by trans- Right caudate nucleus 3.29 3.81 ± 0.46 forming standard anatomical coordinates (from an Left putamen 3.47 4.12 ± 0.74 anatomical atlas) to functional imaging coordinates.18 The Right putamen 3.48 3.78 ± 0.68 technique involved estimating the position of the inter- Left occipital cortex 2.66 3.38 ± 0.61 commissural line (AC-PC line) directly from the PET im- Right occipital cortex 2.76 3.56 ± 0.52 age and orientating the PET image about this line.19 The Left cerebellum 3.32 3.78 ± 0.37 Right cerebellum 2.96 3.74 ± 0.60 PET slices were then directly comparable with atlas slices. Regions placed on the PET image allowed regional val- *Values are expressed as mean ± SD. ues of CMRO2 to be obtained. The results were com- pared with those from a group of 9 normal subjects (wom- en older than childbearing age and men older than 30 arithmetic. He denied having any problems with mobil- years [mean age, 59.9 years]). These subjects were asymp- ity or stiffness. His wife had noticed that his behavior was tomatic, with normal results on clinical examinations, becoming more obsessive and that he was more verbally scoring at least 29/30 on the Mini-Mental State Exami- aggressive than he used to be. nation. The mean±SD CMRO2 value for each cortical re- There was no significant medical history. He was gion (left and right hemispheres) is shown in the Table. married, smoked 10 cigarettes per day, and had mild al- Individual values are given for each region, and those out- cohol intake. There was a family history of depression side the 95% reference range of the normal data differ in both his father and his brother. He was not taking any significantly from normal at a level of P,.05. regular medications. The findings of his general exami- Statistically significant areas of hypometabolism in- nation were normal, and his blood pressure was 100/70 cluded the frontal, temporal (predominantly left and pos- mm Hg. He had mildly reduced movement of his right teriorly), and parietal lobes (predominantly left). Me- arm on walking and on examination had a mildly in- tabolism in the left caudate was just below the 95% creased tone of his upper limbs, more marked on the right, reference range. The occipital and cerebellar rates of me- with cogwheeling rigidity. His limb power was normal, tabolism were normal. A diagnosis of probable AD with with symmetrical reflexes and flexor plantar responses. extrapyramidal features was made. On sensory examination, he had mildly reduced vibra- Over the following year, there was a progressive de- tion and joint position sense in his lower limbs. He had terioration in the patient’s mental status: his verbal and a positive pout reflex. He was mildly dyspraxic, being un- performance IQ scores had declined to 73 and 71, re- able to copy complex gestures.