Personal Case Report: Visual Hallucinations post-op

Personal Case Report: Visual Hallucinations post-op

Interesting case last week - post-op Mr C was told by his surgeon that he'd had a myocardial infarction during recovery. A week or so later, his memory has turned this MI into a stroke. On a medical review of the frail surgical patients, Mr C happily told me he was getting over his stroke OK, but was troubled by odd hallucinations.

It's not uncommon for the elderly to experience confusion, fluctuating consciousness and hallucinations during acute illness - this usually represents delirium, a global, reversible brain phenomenon usually caused by infection, metabolic disturbance, drugs (prescribed, illicit and socially-acceptable) or drug withdrawal.

But my patient didn't quite fit the pattern. His memory wasn't great, but this doesn't appear to have changed recently. He was quite alert. And his hallucinations were, when he went into them in more depth, almost exclusively appearing to the left of his bed, usually seeming to be fleeting images of people, disappearing beyond the field of view as soon as they appear. To his left was a window, through which was the nurses station. Such fleeting mirages on a hospital ward are usually called 'nurses'. Ha ha.

This kind of hallucination sounded a little like the hallucinations often described in Parkinson's Disease - patients will often describe feeling like there is someone standing just outside their visual field ('presence' hallucinations), or seeing animals or dark shapes flitting out of their sight. But the left-sided phenomenon was odd.

A screeening neurological examination - tone and power in the limbs, a brief check of facial power and eye movements - was normal. Crude checking of visual fields however was grossly abnormal. This man had no vision to the left of midline.

More accurate visual field examination followed - demonstrating a left homonymous hemianopia - the loss of the left half of each eye's visual field.

For med students / junior doctors - Where do you think this man's stroke was? Bamford classification (TACS, PACS, PoCS or LacS) or anatomically. Or both.

Then look at the CT images:

The CT scan demonstrates a right-sided infarct in the occipital lobe - a stroke at the back of the brain on the right, which fits with the clinical picture of left-sided visual loss (the nerves from the eyes cross over in the middle of the brain). There is a small amount of haemmorhage within the infarct, but outside the acute period (first few hours) this doesn't affect management significantly.

Learning points? Clinical examination is still useful. Listen to your patient to guide your examination. Don't assume an elderly patient is confused just because they're describing odd phenomena.

Further, I'm now wondering if the visual hallucinations are similar to the Charles-Bonnet syndrome, or whether this is some kind of excitatory effect from the small amount of haemorrhage into the infarct.