Letter

Don’t forget cortical Lewy bodies

To the Editor

The recent Images in Neuroscience contribution to thejournal from Lim and colleagues1 is an interesting onefor some further discussion. The authors present a manwith ‘Parkinson’s disease’, six months ‘of hallucinationsand confusion’ who was noted by his family ‘to be forget-ful’. He became transiently ‘agitated and combative’ afterprostate surgery with epidural anaesthesia and a diagnosisof pneumocephalus was made on the basis of CT imaging.The authors make it clear that they consider pneumoceph-alus is the cause of the patient’s acute confusion. However,while the acute radiological diagnosis was pneumocephalusthe clinical diagnosis for this man’s apparent deteriorationis probably more complex.

Based on the previous history this man is highly likely tohave cortical Lewy body pathology. Whether he has‘dementia with Lewy bodies’ or ‘Parkinson’s disease withdementia’ would depend on the duration of the Parkinso-nian, compared to the cognitive, symptoms. In any caseemerging evidence suggests that this distinction may proveto be entirely arbitrary.2 The important point for this dis-cussion is that patients with cortical Lewy body disease(s)have spontaneously fluctuating confusion and are notori-ous for experiencing transient delirium with intercurrent ill-nesses including surgical procedures.

While few would disagree with the notion that intra-cranial air is not a good thing, it may not be, therefore,the whole story. It is quite likely that pre-existing corticalLewy body pathology was also a contributing factor. It isalso possible that his acute and transient mental deterio-ration was entirely due to Lewy body pathology but, inthe course of investigating this deterioration, purely inci-dental pneumocephalus was discovered (note that theamount of gas in the image is negligible). So can pneumo-cephalus alone cause acute confusion? The authors cite asingle case report3 to suggest it can. However, this case re-port was an 83 year old man whose cognitive evaluationwent no further than the Abbreviated Mental Test in

the acute stage. No longitudinal evaluation was under-taken to see whether his acute delirium was the harbingerof incipient dementia. On the other hand, a review of 295cases of pneumocephalus found that headache was thecommonest manifestation while acute confusion wasrare.4 A more compelling case of confusion due to pneu-mocephalus has been reported though, unlike the presentcase, the imaging abnormality was considerably moreextensive and caused frontal lobe distortion.5 It is impos-sible to rule out the possibility that the clinical picture ofLim et al’s case was exacerbated by pneumocephalus,though on the balance of probabilities it is, perhaps, morelikely that his pre-existing degenerative disorder was amore significant determinant. Either way his ongoing hal-lucinations, confusion and forgetfulness might be palliatedby a cholinesterase inhibitor.2

References

1. Lim ECH, Teoh H-L, Seet RCS. Acute confusion and agitation afterepidural anaesthesia. J Clin Neurosci 2005;12:790.

2. Thomas AJ, Burn DJ, Rowan EN, et al. A comparison of the efficacyof donepezil in Parkinson’s disease with dementia and dementia withLewy bodies. Int J Geriatr Psychiatry 2005;20:938–44.

3. Chan YP, Yau CY, Lewis RR, Kinirons MT. Acute confusionsecondary to pneumocephalus in an elderly patient. Age Ageing

2000;29:365–7.4. Markham JW. The clinical features of pneumocephalus based upon a

survey of 284 cases with report of 11 additional cases. Acta Neurochir

(Wien) 1967;16:1–78.5. Counselman FL, Derkum S. An unusual cause of altered mental status.

J Emerg Med 1995;13:757–63.

Peter J. NestorUniversity of Cambridge Neurology Unit,

Addenbrooke’s Hospital,

Cambridge, CB2 2QQ,

United Kingdom

Tel.: +44 (0)1223 355 294x393,fax: +44 (0) 1223 336 941

E-mail address: peter.nestor@mrc-cbu.cam.ac.uk

doi:10.1016/j.jocn.2005.12.001

www.elsevier.com/locate/jocn

Journal of Clinical Neuroscience 14 (2007) 296–297