I can tell by the way you snore...

Wouldn't it be great if we didn't have to do expensive polysomnograms, read incomprehensible charts, and (in the public setting) wait for months for a sleep study? All just to diagnose OSA and say to a patient ok, now we are sure you need treatment. Especially when he's been falling asleep in your waiting room or just come in with head bandaged after his lorry overturned. You know he has OSA.

Well, it seems the people in Brisbane have found a way.

I have been thinking along the lines of a biochemical marker or something that might be detected in the breath. Imagine bus drivers having to check in for a urine test or breathalyser test before they board and you get the idea.

The sleep team in University of Queensland have reported they can HEAR that you have OSA.

I guess I have always had this hunch. Haven't you? There's a rhythmic hiss in the meeting room and you thought it was the air-condition vent until the guy next to you starts nodding. You think the ventilator is leaking when you realise your assistant in OR is stertoring. You know. Nothing scientific. No data to base this on. Just that visceral hunch that there's no way you can be breathing right during sleep if you are hissing with every breath through the day.

But these guys down under have made a science of it and claim over 90% sensitivity and specificity by simply analysing the audio recording of your snore!

Read the Article at HealthJockey.com

Review the scientific papers related to snoring by their lead researcher Dr. Udantha Abeyratne.

Post exposure prophylaxis for Varicella?

The author of this blog is currently in day 7 of illness, suffering from a moderate form of varicella. In spite of starting acyclovir (thanks to vigilant and quick-acting wife) on the day of eruptions, the disease process was not halted and vesicles are florid. While we are taking precautions against pneumonia, encephalitis, and other adult-onset associated complications, it is my 2yr old that I agonise about.

He is an 'exposed' individual. Varicella infections in children are mild and rarely complicated. Being an otolaryngologist, however, we know that Ramsay-Hunt (herpes zoster oticus; i.e. reactivation of virus in facial nerve) syndrome causes debilitating facial palsy - sometimes irreversible. Shingles is painful, too. My question is, should I bother vaccinating him now? He was planned for his jab next week, but now that he is exposed, shouldn't I just wait and see if he develops the infection which would obviate vaccination altogether?

Well, this is where the evidence is really useful:

According to the Cochrane review of randomized trials evaluating varicella vaccine in children and adults; from 3 trials with 110 healthy siblings of household contacts where they received post-exposure prophylaxis (PEP) within 3 days of exposure or not at all:
- varicella developed in 18% (PEP) vs. 78% (no PEP) (p < 0.05)
- moderate to severe varicella developed in 2% (PEP) vs. 76% (no PEP) (p < 0.05)
- PEP group who developed varicella had mild disease (< 50 skin lesions)
- no trials reported on adverse events following immunization

Also, for all my healthcare worker friends out there, don't be a hero (or a chicken, depending why you're delaying.) Get yourself jabbed now! Varicella vaccine is recommended for those who have never had chickenpox and are seronegative for varicella antibodies. The caveat (or bonus) is 1-5% adult develop varicella-like rashes that shed the virus and should be removed from patient contact (perfect excuse for holiday, no?) [Am Fam Physician 1997 Dec;56(9):2291]

Unilateral hearing loss: To MR or not to MR?

The occasional case of unilateral hearing loss sometimes poses a dilemma. Should we order MRIs to rule out acoustic neuroma for every case of unexplained unilateral SNHL when the incidence is only 1 in 100,000?

Perhaps our suspicion index can be guided by the symptom profile of acoustic neuroma where there is:
93.4% hearing impairment
75.5% tinnitus
40.6% vertigo
38.8% unsteadiness

Hearing loss can be sudden (12-47%) or insidious

Ho & Kveton, 2002, recommended a protocol for investigation:
- for patients with limited symptoms (isolated vertigo, historically explained unilateral hearing loss or tinnitus, or symmetrical hearing loss; estimated risk of acoustic neuroma < 5%): ABR as initial test and MRI if abnormal ABR
- for patients with intermediate symptoms (sudden sensorineural hearing loss or unexplained persistent unilateral tinnitus; estimated risk of acoustic neuroma 5-30%): MRI as initial test
- for high-risk patients with combination of unilateral asymmetric sensorineural hearing loss, tinnitus and decreased speech discrimination (estimated risk of acoustic neuroma > 30%): MRI with gadolinium initially and periodic ABR testing if negative MRI


On the other hand, it is worth remembering that tumor growth is on average 1-2.3 mm/year and less than 30% grow > 2 mm/year so that serial MRIs are hardly helpful and may not require any intervention in the elderly.

References
Arch Otolaryngol Head Neck Surg 2004 Feb;130(2):216
Neurosurgery 2006 Jul;59(1):67
J Laryngol Otol 1994 Feb;108(2):116
Am J Otolaryngol 1999 May-Jun;20(3):157
Neurosurgery 1997 Jan;40(1):1
Otolaryngol Clin North Am. 2002 Apr;35(2):393-404, viii

Risk of CA in MNG

I was asked this by a friend who has a progressively enlarging non-toxic goitre and a CT scan that showed a huge multinodular goitre with tracheal compression: do I need surgery and why? Should the whole thyroid be removed or can some be spared?

My quick answer was YES you need surgery, and a total thyroidectomy, both because of the risk of occult carcinoma. An FNAC can easily miss malignant foci, MNGs have a risk of malignant change, imaging has no reliable sign of malignancy, and compression heralds worse complications (with or without op).

But what's the risk exactly, and what does evidence say about how much of thyroid to remove? This is what the evidence says:

1)In a review of 317 patients operated for multinodular goiter, the incidence of occult micro-carcinoma was 3.3% (Wahl RA, Goretzki P, Meybier H, Nitschke J, Linder M, Roher HD. Coexistence of hyperthyroidism and thyroid cancer. World J Surg 1982; 6: 385-390)
2) Another review of 98 total thyroidectomies done for MNGs revealed an incidence of 10 cases (10.2 percent) occult carcinomas - seven patients were diagnosed with papillary carcinoma, two with the follicular variant of papillary and one with follicular carcinoma.
http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijs/vol17n1/goiter.xml
2) Total thryoidectomy may avoid need for reoperation in case of incidental thyroid
cancer; a study of 218 patients with euthyroid multinodular goiter and no suspicion for malignancy were randomized to total or near-total thyroidectomy (remnant tissue < 1 g) vs. bilateral subtotal thyroidectomy (remnant tissue> 5g); no significant differences in rates of temporary unilateral vocal cord dysfunction (0.9% vs. 0.9%), hypoparathyroidism (1.8% vs.0.9%) or finding of papillary cancer (9.2% vs. 7.3%) (Arch Surg 2004 Feb;139(2):179 in JAMA 2004 May 5;291(17):2058)

So, with a risk of somewhere between 3-10% occult carcinoma (papillary still being the commonest) and near-total also mean could-miss; I think it's still right to say MNGs should be treated with total thyroidectomies unless surgically difficult; upon which post-operative suppressive thyroxine may be an option.