I was called in last week to manage this case and I found a few key decision points that required me to think a little harder than usual so I thought I would put it up for discussion.
29 yo. man flown in from Balgo (About half way between Broome and Alice Springs – middle of the Tanami Desert). Presented to the Nursing POst with headache (similar to usual ‘migraines’), he was treated with Aspalgin (aspirin+codeine) and sent home. Represented the next day with fever (40+), severe headaches and was beginning to get confused / inappropriate / drowsy. On advice from RFDS he was given empirical meningitis ABs = ceftriaxone 1g and benzylpenicillin 1.2g IV, retrieval was arranged ASAP.
On arrival to Broome the chap was GCS 12- 13, confused, intermittently recognised his wife, sweaty / febrile. Other obs – normotensive, p = 110, oxygenation OK, pupils equal, a little sluggish. He had normal power in 4 limbs but was noted to have a few jerks of clonus intermittently – no overt seizures. Further exam showed no other clear focus of infection, no rash, urine NAD. PMHx from wife – migraines only, no meds, no drugs, fit guy.
I have started doing optic nerve sheath US for patients like this – his was normal – average diameter 4 mm. Check out the link if you are keen. Now first question – do you need to CT his brain prior to doing an LP? Well this is controversial in that some argue that coning / herniation is a consequence of the infection rather than due to the LP, however others argue that the risk of not doing the LP is low – the treatment is essentially the same and we can use a later LP to make a diagnosis using non-culture techniques. My reading of the papers is that the real contraindication to an LP is signs of raised ICP – these may be clinical (low GCS, pupils, brainstem / focal signs, seizures) OR radiological (CT or the trusty USS) – if either is abnormal – don’t do it, if both are good then you are probably OK – jab away.
Working diagnosis: for me it looked like encephalitis – just a gut thing, no evidence. Recent epidemic of Murray Valley Encephalitis in the region – and this man was a visitor – so prone to primary infection. So my money was on MVE. However we needed to cover for all the usual suspects. What antibiotics would you use in a case were meningitis is likely? Our management = top up the ceftriaxone to 4 g, continue the penicillin and add in Vanc and Aciclovir. eMJA did a review a few years back which is clear on what to give and what doses. I think the thing I learned here was that if you reckon a patient actually has a bad CNS infection (not just having a low probability work-up) then treat early with proper big dose ABs. I think a lot of us are happy with a gram of Cef and then “rest on our laurels”, but this really does not cut it – you need to give big doses early. FYI we gave dexamaethasone – seems to be the done thing…though the stats are not overwhelming – likely prevents hearing loss with not much downside.
Anyway we did an LP – which was crystal clear – no cells, no reds, no bugs, opening pressure = PLUM normal. So what was happening? Was it something else?? I started thinking: ?neurolept malignant, ? other drugs – went back and took history from the wife – no suggestion of drugs etc
We transferred south to ICU (home of LITFL blog – highly recommended reading) and they continued the ABs – and the CSF PCR eventually came back + for MVE (Murray Valley Encephalitis).