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PMID: 22661569 J Am Acad Orthop Surg. 2012 Jun;20(6):393-401.

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Spinal muscular atrophy: manifestations and management.

Mesfin A Sponseller PD Leet AI

Mesfin A, JAAOS 2012

Pubmed

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by a homozygous deletion in the SMN1 gene and is manifested by loss of the anterior horn cells of the spinal cord. Classifications of the disorder are based on age of onset and the patient's level of function. Scoliosis and hip subluxation or dislocation are two musculoskeletal manifestations associated with SMA. Severity of scoliosis correlates with age at presentation. Bracing has been unsuccessful in halting curve progression and may interfere with respiratory effort. Early onset scoliosis associated with SMA has been successfully treated with growing rod constructs, and posterior spinal fusion can be used in older children. Hip subluxations and dislocations are best treated nonsurgically if the patient reports no pain because a high rate of recurrent dislocation has been reported with surgical intervention.

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100% No (20/20)

0% Undecided (0/20)

⁴

What level of evidence do you think this article is?

4% Level 1 (1/21)

14% Level 2 (3/21)

42% Level 3 (9/21)

14% Level 4 (3/21)

23% Level 5 (5/21)

Cards

1 of 0

(SBQ13PE.106) Survival motor neuron protein deficiency leads to:

QID: 5331

Type & Select Correct Answer

Type in at least one full word to see suggestions list

Progressive replacement of muscle tissue with fibrous and fatty tissue, causing calf pseudohypertrophy

12%

(372/3108)

Loss of anterior horn cells and progressive muscle weakness

78%

(2421/3108)

Abnormal chondroid production by chondroblasts in the proliferative zone of the physis

1%

(36/3108)

Disturbances in cell metabolism with accumulation of sphingolipids in the liver, spleen and bone marrow

3%

(104/3108)

Fetal acetylcholine receptor inhibition and nonprogressive joint contractures

5%

(156/3108)

Select Answer to see Preferred Response

SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic

(OBQ13.104) A newborn infant is born with the physical exam finding shown in the video below. In addition, the child has absent deep tendon reflexes and hypotonia. Which of the following abnormalities is most likely responsible for these findings?

QID: 4739

FIGURES:

V

Type & Select Correct Answer

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Gene mutation in SMN1

61%

(2784/4528)

Deficiency of Dystrophin protein

13%

(580/4528)

Beta-galactosidase deficiency

16%

(709/4528)

Gene mutation in COMP

5%

(233/4528)

Gene mutation in COL1A1

4%

(176/4528)

Select Answer to see Preferred Response

SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic

(SBQ13PE.2) A 12-month-old male presents with symmetric, progressive weakness that is more profound in lower extremity than upper extremity. On physical exam, he can sit but cannot walk. He has tongue fasciculations and absent deep tendon reflexes. Serum creatine phosphokinase and aldolase levels are normal. Which of the following genetic mutations or deletions is responsible for his condition?

QID: 4915

Type & Select Correct Answer

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Dystrophin gene

27%

(1519/5580)

PMP22 gene

6%

(322/5580)

Androgen receptor gene

1%

(75/5580)

SMN-1 gene

55%

(3087/5580)

Frataxin gene

10%

(536/5580)

Select Answer to see Preferred Response

SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic

(OBQ12.233) A 3-month-old infant presents to your clinic with difficulty moving his extremities. The child had an uneventful prenatal course and birth, but since birth he has had poor head control and difficulty feeding. On physical exam, he is able to move all extremities, but he moves his upper extremities more than his lower extremities, and his hands more than his shoulders. He has no spasticity, but global weakness. The patient’s deep tendon reflexes are absent, but he has tongue fasciculations. What is the cellular pathology and prognosis for this patient?

QID: 4593

Type & Select Correct Answer

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The patient has a nonprogressive injury to his brain, and he will likely require multiple orthopaedic surgeries in the future as a result of muscle imbalance

8%

(272/3236)

The patient has an absent dystrophin protein and will likely require a wheelchair by the age of 15 and will die of cardiorespiratory problems by the age of 20

16%

(524/3236)

The child will have a progressive loss of alpha-motor neurons in anterior horn of spinal cord. He will have difficulty walking, but will be able to sit independently and will likely live into the fifth decade of life

16%

(511/3236)

The child will have a progressive loss of alpha-motor neurons in anterior horn of spinal cord and will unlikely live past the age of two

57%

(1860/3236)

The child will likely go on to develop a cavus foot and hammer toes, but he should live a full healthy life

1%

(34/3236)

Select Answer to see Preferred Response

SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic

(SBQ04PE.40) An autosomal recessive disorder caused by a homozoygous deletion in the survival motor neuron 1 (SMN1) gene would result in which of the following?

QID: 2225

Type & Select Correct Answer

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Global hypotonia, difficulty swallowing, absent deep tendon reflexes, and tongue atrophy, with disease onset within the first 6 months of birth.

45%

(877/1947)

Delayed motor milestones, scoliosis, and joint contracture, with disease onset around 6-18 months of age

14%

(268/1947)

Scoliosis, hand tremors, increased lumbar lordosis, and bilateral Trendelenburg lurch, with disease onset later in life (>18 months of age).

6%

(123/1947)

Any of the above

29%

(567/1947)

None of the above

4%

(77/1947)

Select Answer to see Preferred Response

SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic