Neurology -- Correspondence for Middelkoop et al., 57 (11) 2117-2120

Correspondence published:

Dementia with Lewy bodies and AD are not associated with occipital lobe atrophy on MRI: G Ransmayr, M Gerlack, K Stadler, and F Aichner (17 July 2002)

Dementia with Lewy bodies and AD are not associated with occipital lobe atrophy on MRI 17 July 2002

G Ransmayr
General Hospital Linz Austria,
M Gerlack, K Stadler, and F Aichner
Send Correspondence to journal:
Re: Dementia with Lewy bodies and AD are not associated with occipital lobe atrophy on MRI

gerhard.Ransmayr{at}akh.linz.at G Ransmayr, et al.

Middlekoop et al. [1] examined whether occipital lobe hypoperfusion and hypometabolism observed in dementia with Lewy bodies (DLB) and sometimes in Alzheimer’s disease (AD) is associated with occipital lobe atrophy. They found normal occipital lobe volumes in both diseases.
We studied 15 patients with probable AD, 15 patients with probable AD (14 DLB and 1AD patient with visual hallucinations) and 12 controls using a similar protocol. The groups had comparable ages (70.4+8, 70.1+9.1, 66+5.9; means + SD; p=0.23, Kruskal-Wallis ANOVA). Length of history of dementia (DLP 2.9+2.5, AD 2.4+1.4 years; p=0.22) and Mini-Mental State Examination scores (DLP 21.0+4.8, AD 18.1+5.2; p=0.85, Mann-Whitney U test) were comparable. The study was performed on a Siemens Magnetom Vision plus 1.5 Tesla MRI unit using T1-weighted, three-dimensional MPRAGE sagittal sequences (slice thickness 1.2 mm, TR 9.7 msec, TE 4 msec, flip angle 12 deg. Matrix 200 x 256 mm, pixel size 1.2 x 0.94mm) and a Allegro work station (ISG Technologies, Canada). Forebrain, occipital lobe and supratentorial subarachnoid space volumes were measured by one experienced person blinded to the diagnosis using a semiautomated segmentation process.
Because of different intracranial volumes (DLB 1262.2+95.9, DAT 1154.2+149.7, controls 1136.1+87.2 cm3; p=.009), occipital lobe (DLB 120.2+12.7, DAT 111.1+13.1, controls 121.6+9.6 cm3) and forebrain volumes (925.8+101.9, DAT 817.6+110.3, controls 897.6+93.86 cm3 were normalized (divided by intracranial volumes). Normalized forebrain volumes (NFV) were significantly smaller in AD (0.71+0.1, p=0.003) and insignificantly smaller in DLB (0.73+0.09, p=0.0.57) than in controls (0.79+0.09), and similar in DLB and AD (p=0.039). Normalized occipital lobe volumes (NOV) were smaller in DLB (0.095+0.01) and AD (0.096+0.01), p=0.02 than in controls (0.107+0.01), p=0.07 and similar in DLB and DAT (p=0.085). NFV minus NOV (DLB 0.64+0.1, AD 0.61+0.1, control 0.68+0.05) were significantly smaller in AD (p-0.0031) and insignificantly smaller in DLB (p=0.072) than in controls, and similar in DLB and AD (p=0.37). NOV divided by NFV minus NOV were similar in all groups (DLB 0.149+0.02, AD 0.155+0.01, controls 0.156+0.02; p=0.39).
Our study, performed in smaller collectives than those of Middlekoop et al. [1], corresponds to previous publications demonstrating forebrain atrophy in AD and mild atrophy also in DLB. [2, 3, 4] In contrast to Middlekoop et al. [1] occipital lobe atrophy was found, which was similar in DLB and AD, and does therefore not explain occipital hypometabolism and hallucinations in DLB.
References:
1) Middlekoop HAM, van der Flier WM, Burton EJ, et al. Dementia with Lewy bodies and AD are not associated with occipital lobe atrophy on MRI. Neurology 2001;57:2117-2120.
2) Mann DM, Snowdon JS. The topographic distribution of brain atrophy in cortical Lewy body disease: Comparison with Alzheimer’s disease. Acta Neuropathol 1995;89:178-183.
3) Hashimoto M, Kitagaki H, Imamura T, et al. Medial temporal and whole brain atrophy in dementia with Lewy bodies: A volumetric MRI study. Neurology 1998;51:357-362.
4) Barber R, Ballard C, McKeith IG, Gholkar A, O’Brien JT. MRI volumetric study of dementia with Lewy bodies: A comparison with AD and vascular dementia. Neurology 2000;54:1304-1309.