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Three Part Question

In [adults presenting with acute confusion without focal neurological signs] is [brain scanning] sensitive enough to rule out [significant intracranial pathology]?

Clinical Scenario

An elderly female patient of 82 presents to the emergency department with acute confusion of unknown cause. She is too delirious to take a history from and has no family present to give a collateral history. There are no focal neurological signs but you still wonder whether to perform a CT or MRI scan to rule out intracranial pathology as a cause of her confusion.

Search Strategy

MEDLINE 1950 to June week 4 2010, EMBASE 1980 to 2010 week 26 and the COCHRANE LIBRARY.
MEDLINE: (exp confusion/ OR exp delirium/) AND (exp Tomography, X-Ray Computed/ or exp Magnetic Resonance Imaging/)limit to human and English language.
EMBASE: (exp confusion/ OR exp delirium/) AND (exp Tomography, X-Ray Computed/ or exp Magnetic Resonance Imaging/)limit to human and English language, limit clinical query to diagnosis(optimised).

Search Outcome

285 papers were found in Medline, 3 of which were relevant. 168 papers were found on Embase, none of which were relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Bruce Naughton, Maureen Moran, Youssef Ghaly et al. March 25 1997 Chicago, USA	96 patients over 70 years of age, classified as having delirium by the Confusion Assesment Method (CAM). Selected from a systematically constructed sample to include equal proportions from the different shifts available at the emergency department.	Prospective, observational study.	Proportion of scans ordered in those with delirium compared to those without delirium but with altered consciousness	Higher rate of scanning in the group with delirium.	Only looking at the elderly population. Small number of positive scans. Short follow up period.
			% of positive scans in those with delirium	15%
			% of positive scans who had acute neurological signs	95.1%
A Hufschmidt, V Shabarin. 2008 Germany	178 patients admited with acute confusion of unknown origin, who received imaging.	Retrospective study.	Positive imaging	25 patients	Retrospective study Originally 294 patients, only 60.5% had imaging. Decisions to scan or not to were poorly recorded in the notes some times.
			Patients with no focal neurological signs but positive imaging	7%: therefore lack of focal neurological signs gives a positive predictive value of 0.93
James Edward Hardy and NIcholas Brennan. 2008 Australia	106 consecutive patients over age of 70, who had a CT scan for presentation of acute confusion.	Randomised control trial	Positve CT scan result	15	Only looking at the elderly population. Small group sample with positive CT scans. Did not follow up thoses without CT scan. Didnt use any diagnostic tools to screen for Delirious patients, just went with what was said in the notes.
			Positive CT scan with no focal neurological signs	1 (only one patient and had suffered a history of falls)

Comment(s)

All three of the papers suggest that a lack of focal neurological signs gives a high positive predictive value for the CT scan to be normal. The only patient on the Hardy et al paper to have a positive CT without any scans had suffered a fall. Both the Hardy et al and the Naughton et al paper come to the conclusion that lack of focal neurological signs or no history of a fall is enough to predict the CT scan will be normal. However both these papers had very small sample sizes and due to the serious nature of missing intracranial pathology, further evidence would be needed. The Hufschmidt et al paper, with the largest population size supports this, as although lack of focal neurological sign had a 0.93 positive predictive value, this still meant 7% of patients would have been missed. The authors feel this is too high a value too ignore.

Clinical Bottom Line

Lack of focal neurological signs and no history of a fall is indicative that the CT scan will most likely be normal. However there is evidence that indicates that this is not always the case and brain imaging should be performed if the clinician feels it is necessary.

References

1. Bruce Naughton, Maureen Moran, Youssef Ghaly et al. Computed Tomography scanning and delirium in elder patients. Journal of Accident and emergency medicine. 1997; 4:1107 - 1110
2. A Hufschmidt, V Shabarin. Diagnostic yield of cerebral imaging in patients with acute confusion. ACTA NEUROLOGICA SCANDINAVICA 2008 118: 245-250
3. James Edward Hardy and NIcholas Brennan. Computerized tomography of the brain for elderly patients presenting to the emergency department with acute confusion. Emergency Medicine Australasia 2008; 20: 420-424