Episode 867: Occult Scaphoid Fractures

09/04/23 • 4 min

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Emergency Medical Minute

Contributor: Nick Tsipis MD

Educational Pearls:

The scaphoid bone is the most proximal carpal bone just distal to the radius
Fractures of the scaphoid bone are sometimes missed by plain X-rays

A 2020 review found a 21.8% incidence of missed scaphoid fractures later diagnosed by advanced imaging modalities
Only MRI has a sensitivity above 90% for diagnosing scaphoid fractures
Sensitivity of plain-film radiography is low unless it is a displaced fracture

Physical examination techniques fail to definitively rule out scaphoid fractures
A 2023 systematic review assessed the sensitivity and specificity of several common physical exam maneuvers:

Tenderness of the anatomical snuffbox has a sensitivity of 92.1% and specificity of 48.4%; i.e. absence reduces the likelihood of an occult scaphoid fracture but does not rule it out
Another common physical exam maneuver is pain with ulnar deviation, which carries a sensitivity of 55.2% and specificity of 76.4%.
Elicitation of pain with supination against resistance demonstrated a sensitivity of 100% and specificity of 97.9% in the study, so the authors recommend externally validating this method

Patients should be counseled on the importance of follow-up given that a fracture may not show up on imaging unless an MRI or repeat XR is done

References

1. Bäcker HC, Wu CH, Strauch RJ. Systematic Review of Diagnosis of Clinically Suspected Scaphoid Fractures. J Wrist Surg. 2020;09(01):081-089. doi:10.1055/s-0039-1693147

2. Coventry L, Oldrini I, Dean B, Novak A, Duckworth A, Metcalfe D. Which clinical features best predict occult scaphoid fractures? A systematic review of diagnostic test accuracy studies. Emerg Med J. 2023;40(8):576 LP - 582. doi:10.1136/emermed-2023-213119

Summarized by Jorge Chalit, OMSII | Edited by Meg Joyce & Jorge Chalit, OMSII

Contributor: Nick Tsipis MD

Educational Pearls:

The scaphoid bone is the most proximal carpal bone just distal to the radius
Fractures of the scaphoid bone are sometimes missed by plain X-rays

A 2020 review found a 21.8% incidence of missed scaphoid fractures later diagnosed by advanced imaging modalities
Only MRI has a sensitivity above 90% for diagnosing scaphoid fractures
Sensitivity of plain-film radiography is low unless it is a displaced fracture

Physical examination techniques fail to definitively rule out scaphoid fractures
A 2023 systematic review assessed the sensitivity and specificity of several common physical exam maneuvers:

Tenderness of the anatomical snuffbox has a sensitivity of 92.1% and specificity of 48.4%; i.e. absence reduces the likelihood of an occult scaphoid fracture but does not rule it out
Another common physical exam maneuver is pain with ulnar deviation, which carries a sensitivity of 55.2% and specificity of 76.4%.
Elicitation of pain with supination against resistance demonstrated a sensitivity of 100% and specificity of 97.9% in the study, so the authors recommend externally validating this method

Patients should be counseled on the importance of follow-up given that a fracture may not show up on imaging unless an MRI or repeat XR is done

References

1. Bäcker HC, Wu CH, Strauch RJ. Systematic Review of Diagnosis of Clinically Suspected Scaphoid Fractures. J Wrist Surg. 2020;09(01):081-089. doi:10.1055/s-0039-1693147

Summarized by Jorge Chalit, OMSII | Edited by Meg Joyce & Jorge Chalit, OMSII

Previous Episode

Podcast 866: Carbamazepine (Tegretol) Overdose

Contributor: Aaron Lessen MD

Educational Pearls:

What is Carbamazepine (Tegretol)?

Carbamazepine is an anti-epileptic drug with mood-stabilizing properties that is used to treat bipolar disorder, epilepsy, and neuropathic pain.
It functions primarily by blocking sodium channels which can prevent repetitive action potential firing.

What are the symptoms of an overdose?

Common initial signs include diminished conscious state, nystagmus, ataxia, hyperreflexia, CNS depression, dystonia, and tachycardia
Severe toxicity can cause seizures, respiratory depression, decreased myocardial contractility, pulmonary edema, hypotension, and dysrhythmias.

How is an overdose treated?

An overdose is treated with large doses of activated charcoal and correction of electrolyte disturbances.
Be ready to intubate given the potential for respiratory depression.
Carbamazepine is moderately dialyzable and dialysis is recommended in severe overdoses.

Additional educational pearl: Individuals in correctional facilities can occasionally self-administer medications which means that medication overdose should still be on the differential for any of these individuals.

References

Epilepsies in children, Young People and adults: NICE guideline [NG217]. National Institute for Health and Care Excellence. (2022, April 27). https://www.nice.org.uk/guidance/ng217
Ghannoum M, Yates C, Galvao TF, Sowinski KM, Vo TH, Coogan A, Gosselin S, Lavergne V, Nolin TD, Hoffman RS; EXTRIP workgroup. Extracorporeal treatment for carbamazepine poisoning: systematic review and recommendations from the EXTRIP workgroup. Clin Toxicol (Phila). 2014 Dec;52(10):993-1004. doi: 10.3109/15563650.2014.973572. Epub 2014 Oct 30. PMID: 25355482; PMCID: PMC4782683.
Seymour JF. Carbamazepine overdose. Features of 33 cases. Drug Saf. 1993 Jan;8(1):81-8. doi: 10.2165/00002018-199308010-00010. PMID: 8471190.
Spiller HA. Management of carbamazepine overdose. Pediatr Emerg Care. 2001 Dec;17(6):452-6. doi: 10.1097/00006565-200112000-00015. PMID: 11753195.
Tran NT, Pralong D, Secrétan AD, Renaud A, Mary G, Nicholas A, Mouton E, Rubio C, Dubost C, Meach F, Bréchet-Bachmann AC, Wolff H. Access to treatment in prison: an inventory of medication preparation and distribution approaches. F1000Res. 2020 May 13;9:357. doi: 10.12688/f1000research.23640.3. PMID: 33123347; PMCID: PMC7570324.

Summarized by Jeffrey Olson, MS2 | Edited by Meg Joyce & Jorge Chalit, OMSII

Next Episode

Episode 868: Airway Management in Obesity

Contributor: Aaron Lessen MD

Educational Pearls:

Why is airway management more difficult in obesity?

Larger body habitus causes the chest to be above the head when the patient is lying supine, creating difficult angles for intubation.
Reduced Functional Residual Capacity (FRC) causes these patients to deoxygenate much more quickly, reducing the amount of time during which the intubation can take place.

What special considerations need to be made?

Positioning. The auditory canal and sternal notch should be aligned in a horizontal plane. Do this by stacking blankets to lift the neck and head. Also, try to make the head itself parallel to the ceiling.
Pre-oxygenation. Use Bi-level Positive Airway Pressure (BiPAP) with Positive End Expiratory Pressure (PEEP) or a Bag-Valve-Mask (BVM) with a PEEP valve. PEEP helps prevent alveoli from collapsing after every breath and improves oxygenation.
Dosing of paralytics. Succinylcholine is dosed on total body weight so the dose will be much larger for the obese patient. Rocuronium is dosed on ideal body weight, but adjusted body weight may also be used in obese cases.

References

De Jong A, Wrigge H, Hedenstierna G, Gattinoni L, Chiumello D, Frat JP, Ball L, Schetz M, Pickkers P, Jaber S. How to ventilate obese patients in the ICU. Intensive Care Med. 2020 Dec;46(12):2423-2435. doi: 10.1007/s00134-020-06286-x. Epub 2020 Oct 23. PMID: 33095284; PMCID: PMC7582031.
Langeron O, Birenbaum A, Le Saché F, Raux M. Airway management in obese patient. Minerva Anestesiol. 2014 Mar;80(3):382-92. Epub 2013 Oct 14. PMID: 24122033.
Sharma S, Arora L. Anesthesia for the Morbidly Obese Patient. Anesthesiol Clin. 2020 Mar;38(1):197-212. doi: 10.1016/j.anclin.2019.10.008. Epub 2020 Jan 2. PMID: 32008653.
Singer BD, Corbridge TC. Basic invasive mechanical ventilation. South Med J. 2009 Dec;102(12):1238-45. doi: 10.1097/SMJ.0b013e3181bfac4f. PMID: 20016432.

Summarized by Jeffrey Olson, MS2 | Edited by Jorge Chalit, OMSII