Left-sided brain injury increases infection risk

By Helen Albert, Senior medwireNews Reporter

Patients with a left-sided brain injury are more likely to develop hospital-acquired infections (HAIs) than those with right-sided injury, show study findings.

"Our findings are consistent with the hypothesis that a left-dominant brain immune network may mediate vulnerability to infection during rehabilitation of patients with stroke or TBI [traumatic brain injury]," say Pasquale Frisina (Kessler Institute for Rehabilitation, West Orange, New Jersey, USA) and colleagues.

As reported in the Archives of Physical Medicine and Rehabilitation, Frisina and team carried out a retrospective evaluation of patients with a left- or right-sided stroke or TBI admitted to hospital between January 2009 and December 2010 to assess whether rates of HAIs differed depending on the side of the brain affected.

In total, 2236 patients with brain injury were admitted during this time. Of these, 163 developed HAIs during inpatient rehabilitation including infection with Clostridium difficile, vancomycin-resistant enterococcus (VRE), methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum b-lactamase (ESBL)-producing bacteria such as Escherichia coli, and urinary catheter infections.

Of the patients who developed HAIs, there were a significantly greater number with left- as opposed to right-sided brain injury, at 60.1% versus 39.9%. In the cohort as a whole, 8.8% of left-sided brain injury patients and 5.8% of right-sided brain injury patients had HAIs, a difference that remained significant.

The difference in infection rate remained significantly higher in patients with left-sided injury after correcting for injury subtype (stroke vs TBI), age, gender, presence of dysphagia, parenteral feeding, or presence of urinary/intravascular catheters, among other factors.

The most common type of infection occurring in the patients with right- and left-sided brain injury was C. difficile (38.03%), followed by MRSA (21.47%), ESBL-producing bacterial infection (21.47%), and VRE (16.56%). In the patients with left-sided injury, C. difficile and VRE infections were particularly common, at 44.90% and 21.43%, respectively, compared with a corresponding rate of 27.69% and 9.23% in patients with right-sided injury.

"Although we were unable to link the increased total infections or increased proportion of C. difficile infections in patients with left-sided brain injury to other factors in our data, further research in larger patient samples is needed to examine whether the side of brain injury interacts with clinical or demographic factors," write the authors.

"If the left-right brain activity balance influences immunity, this is important to consider in planning noninvasive brain stimulation techniques such as transcranial magnetic stimulation or transcranial direct current electrical stimulation of the brain," they suggest.

"Although noninvasive stimulation that increases left-sided brain activity and dominance might improve immune capacity and function, some noninvasive techniques may inhibit left-sided brain activity, and these might have adverse effects on health outcomes after stroke by increasing the incidence of HAIs."

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