Kiss of the spider

We discussed many interesting topics today. Here's some info on two of them.

Brown recluse spider bites: These spiders belong to the Loxosceles genus and are commonly found in the south, west and midwest US so we don't see cases in Toronto that often. The brown recluse spiders have a brownish colour with a violin like mark on their head, though victims often fail no notice the spider. Bites typically occur on the upper arm, thorax, or inner thigh and happen most commonly indoors. Bites are rare on hands and feet.

The initial brown recluse bite is painless and is followed by a red plaque that can necrose in the next 24-48h and form an eschar over the ensuing days. Systemic symptoms are rare. Treatment consists of general wound care and tetanus prophylaxis. Sometimes Dapsone is used for prevention of wound progression, but there is no evidence from human studies. Here's a good review article from NEJM on Loxosceles and other spider bites.


Treatment of AAA: We touched briefly on the relative advantages of endovascular vs. open repairs for AAA. Remember that aneurysm size is a key factor on deciding how to manage AAA:

- For aneurysms 3 - 4 cm we do survelillance with U/S every 2-3 years
- For aneurysms 4 - 5.4 cm surveillance is more frequent, every 6 mo- 1 year
- At or above 5.5 cm the risk of rupture becomes greater and consideration for repair is recommended, if the aneurysm is > 2x the diameter of the normal aorta repair is also recommended
- Any symptomatic aneurysm should be considered for repair !!!

While short term mortality for endovascular repair is lower, the 2 year outcomes show similar mortality with more complications as compared to surgery. This recent trial and its accompanying editorial give a good overview of the current thinking on the topic.

Cheers

Thrombolysis in PE

Today we discussed a patient who presented with a pulmonary embolism. Indications/Evidence for thrombolysis was discussed.

To Summarize:

In 2002, a paper in NEJM compared Aleplase and Heparin vs Heparin alone and demonstrated that patients in the alteplase arm had improved clinical courses. All patients had submassive PE (and evidence of RV dysfunction or Pulmonary HTN) without arterial hypotension. This was driven by escalation of therapy in the placebo arm, not death.

A 2004 metanalysis demonstrated thrombolytic therapy compared with heparin was associated with a significant reduction in recurrent pulmonary embolism or death (9.4% versus 19.0%) in studies that enrolled patients with hemodynamically unstable PEs.

Two pro and con commentaries were published in Archives of Internal Medicine in 2005 and are good reads.

Finally, a recent NEJM review can be found here.

Overall, this is an area with uncertaintly and more RCT evidence is needed.

Rash and Fever

Today we discussed an approach to a patient presenting with fever and rash who ultimately seemed to have a drug reaction to his antiretroviral medications. We focused our discussion around a differential diagnosis of a rash in this context while touching briefly on immune reonstitution inflammatory syndrome.

Drug hypersensitivity syndromes manifest as part of a triad: fever, rash and end organ involvement (hepatitis, thyroiditis, lymphadenopthy, renal failure). Stopping the offending drug and providing supportive care is the cornerstone of treatment.

With regards to timing of therapy in patients with TB and HIV, here is a NEJM article .

Panhypopituitarism

Today we discussed an a case of hyponatremia that eventually led to the diagnosis of panhypopituitarism.

This can be a very difficult diagnosis to make due to the non-specific symptoms that a patient complains of (as was seen here).

Etiologies incluede;
1) Brain Damage (Traumatic, radiation, SAH, CVA, Surgery)
2) Neoplastic (originating in the pituitary or compression from outside)
3) Infectious
4) Infarction (Sheehan's, apoplexy)
5) Autoimmune
6) Infiltrative (hemochromatosis, histiocytosis)
7) Congenital

Here is a recent review from Lancet that highlights diagnosis and management.