Blank

Author: Derek Moore

Topic updated on 02/25/13 7:51pm

Please Rate Educational Value!

3.0

Average 3.0 of 5 Ratings

Qbank (5 Questions)

TAG

(OBQ08.30) Which of the following nerves has the most favorable regenerative potential in restoring motor function after a graft repair within half a year after being injured? Topic

Review Topic

1. Median
2. Ulnar
3. Radial
4. Tibial
5. Peroneal

PREFERRED RESPONSE ▶

DISCUSSION: Of the choices listed, the radial nerve has the best opportunity for recovery.

Roganovic performed a prospective study of 393 graft repairs of the median, ulnar, radial, tibial, peroneal, femoral, and musculocutaneous nerves showed that peripheral nerves differ significantly regarding the motor recovery potential, and the expression of differences depends on the level of nerve repair. The following nerves had excellent recovery potential: the radial, musculocutaneous, and femoral nerves. The following nerves had moderate recovery potential: the median, ulnar, and tibial nerves. The following nerve had poor recovery potential: the peroneal nerve.

Mohler et al, recommends testing nerve action potentials at the time of nerve exploration to guide surgical treatment.

REFERENCES:

1. Roganovic, Pavlicevic: Difference in recovery potential of peripheral nerves after graft repairs. Neurosurgery 2006;59:621-633. PMID:16955044 (Link to Abstract)

2. Mohler, Hanel: Closed fractures complicated by peripheral nerve injury. JAAOS 2006;14:32-37. PMID:16394165 (Link to Abstract)

Question Authors:

Sam Cho MD, Patrick McCulloch MD, Ben Taylor MD,

Please Rate Educational Value!

3.0

Average 3.0 of 12 Ratings

TAG

(OBQ05.66) Axon regeneration almost always occurs following a Seddon second-degree nerve injury, also known as axonotmesis, because what anatomic structure is not injured. Topic

Review Topic

1. Epineurium
2. Endoneurium
3. Perineurium
4. Myelin sheath
5. Schwann cell

PREFERRED RESPONSE ▶

DISCUSSION: By the Seddon classification there are three grades of injury. 1st degree injury or neuropraxia is a nerve bruise with axonal continuity leading to a reversible conduction deficit that resolves with time without Wallerian degeneration. 2nd degree injury or axonotmesis is when there is a disruption to the axon and myelin sheath with an intact epineurium - recovery is possible due to the integrity of this intact epineurial connective tissue layer surrounding the nerve. 3rd degree injury or neurotmesis is the most severe form of injury in the Sedon classification and represents complete nerve injury with disruption of axon, myelin sheath and epineurium - in these injuries surgical repair is indicated because there will not be spontaneous recovery.

REFERENCES:

1. Trumble TE (ed): Hand Surgery Update 3: Hand, Elbow, & Shoulder. Rosemont, IL, American Society for Surgery of the Hand, 2003, pp. 287-297.

Question Authors:

Mark Vitale MD, Derek Moore, Mark Vitale MD,

Please Rate Educational Value!

3.0

Average 3.0 of 3 Ratings

TAG

(OBQ05.218) Vitamin B12 deficiency is a known cause of which the following? Topic

Review Topic

1. Inability to whistle
2. Peripheral sensory neuropathy
3. Increased deep tendon reflexes
4. Urinary retention
5. Hydrophobia

PREFERRED RESPONSE ▶

DISCUSSION: Vitamin B12 deficiency is a known cause of peripheral sensory neuropathy and B12 levels should be evaluated in patients presenting with peripheral sensory neuropathy. It is associated with decreased deep tendon reflexes, pathologic reflexes like babinski's sign, and fatigue/depression. The inability to whistle is associated with fascioscapular dystrophy. Hydrophobia is associated with rabies infection.

Smith and Singleton evaluated 138 patients referred with predominantly sensory symptoms to identify a standardized approach to diagnosis. They recommend that patients be tested for glucose tolerance and vitamin B(12) concentration in all cases, but that other tests should be performed only when the clinical scenario is suggestive.

Steiner et al. describe a case report of a patient with vitamin B12 sensory peripheral neuropathy and associated EMG evidence of nerve demyelination as the potential cause for the observed clinical symptoms.

REFERENCES:

1. Smith AG, Singleton JR. The diagnostic yield of a standardized approach to idiopathic sensory-predominant neuropathy. Arch Intern Med. 2004 May 10;164(9):1021-5. PMID:15136313 (Link to Abstract)

2. Steiner I, Kidron D, Soffer D, Wirguin I, Abramsky O. Sensory peripheral neuropathy of vitamin B12 deficiency: a primary demyelinating disease? J Neurol. 1988 Jan;235(3):163-4. PMID:2835439 (Link to Abstract)

Question Authors:

Patrick O'Donnell MD/PhD, Patrick McCulloch MD, Ben Taylor MD,

Please Rate Educational Value!

3.0

Average 3.0 of 5 Ratings

TAG

(OBQ04.248) Which of the following structures are slowly adapting skin receptors that detect pressure, texture, and low frequency vibration and are best evaluated by static two-point discrimination? Topic

Review Topic

1. Meissner's corpuscles
2. Pacinian corpuscles
3. Merkel's receptor
4. Free nerve endings
5. Ruffini corpuscles

PREFERRED RESPONSE ▶

DISCUSSION: Merkel's skin receptors are slowly adapting skin receptors that detect pressure, texture, and low frequency vibration and can be appropriately evaluated by static two-point discrimination. Merkel's disk receptors adapt slowly and sense sustained pressure, texture, and low-frequency vibrations.

Szabo et al state in their review that static and moving two point discrimination are best to initially evaluate innervation density for both quickly and slowly adapting fibers. Vibratory moving 2 point discrimination is best for evaluation of quickly adapting fibers.

Meissner corpuscle, a rapidly adapting sensory receptor, is very sensitive to touch. Pacinian corpuscles are ovoid in shape, measuring approximately 1 mm in length. They respond to high-frequency vibration and rapid indentations of the skin. Ruffini corpuscles are slowly adapting receptors that detect stretching of the skin.

Illustration A demonstrates Meissner's corpuscles (A), Pacinian corpuscles (B), Merkel's receptor (C), free nerve ending (D), and Ruffini corpuscles (E). Illustration B displays the function and location of the receptors.

Illustrations: A

REFERENCES:

1. Manske PR (ed): Hand Surgery Update. Englewood, CO, American Society for Surgery of the Hand, 1994, p 223

2. Szabo RM, Madison M. Carpal tunnel syndrome. Orthop Clin North Am. 1992 Jan;23(1):103-9. Review. PMID:1729659 (Link to Abstract)

Question Authors:

Michael Hughes MD, John Badylak MD, Dave Marcu MD,

Please Rate Educational Value!

2.0

Average 2.0 of 10 Ratings

Evidence & References Show References

Level of Evidence 4 (Case Series)

Smith AG, Singleton JR. The diagnostic yield of a standardized approach to idiopathic sensory-predominant neuropathy. Arch Intern Med. 2004 May 10;164(9):1021-5. PMID:15136313 (Link to Abstract)
Szabo RM, Madison M. Carpal tunnel syndrome. Orthop Clin North Am. 1992 Jan;23(1):103-9. Review. PMID:1729659 (Link to Abstract)

Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions, Personal Observations, and Biomechanic Studies)

Steiner I, Kidron D, Soffer D, Wirguin I, Abramsky O. Sensory peripheral neuropathy of vitamin B12 deficiency: a primary demyelinating disease? J Neurol. 1988 Jan;235(3):163-4. PMID:2835439 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Trumble TE (ed): Hand Surgery Update 3: Hand, Elbow, & Shoulder. Rosemont, IL, American Society for Surgery of the Hand, 2003, pp. 287-297.
Manske PR (ed): Hand Surgery Update. Englewood, CO, American Society for Surgery of the Hand, 1994, p 223

Undefined

Roganovic, Pavlicevic: Difference in recovery potential of peripheral nerves after graft repairs. Neurosurgery 2006;59:621-633. PMID:16955044 (Link to Abstract)
Mohler, Hanel: Closed fractures complicated by peripheral nerve injury. JAAOS 2006;14:32-37. PMID:16394165 (Link to Abstract)

Topic Comments

Subscribe status: On Off

Recent on Bottom | Recent on Top

Page:1

Blank

Qbank (5 Questions)

Question Comments

Question Comments

Question Comments

Question Comments

Evidence & References Show References

Topic Comments