Examkin

Question

Difficulty: MediumPediatric Neurologic Disorders

A 13-year-old boy is brought to the pediatric neurology clinic by his parents due to progressive walking difficulties over the last 18 months. He frequently trips and recently had to stop playing on his school basketball team because he loses his balance easily. The parents note that his 10-year-old brother has also begun to display similar clumsiness. The patient's vital signs are within normal limits. Physical examination reveals high-arched feet and a noticeable lateral curvature of the thoracic spine. Neurological examination demonstrates a wide-based, unsteady gait. Deep tendon reflexes are absent at the knees and ankles, and there is markedly decreased vibratory and proprioceptive sensation in both lower extremities. Motor strength is mildly decreased in the distal lower extremities. Which of the following investigations is most appropriate to evaluate for the leading cause of mortality associated with this patient's underlying condition?

  1. A
    Measurement of serum alpha-fetoprotein
  2. B
    Electromyography and nerve conduction studies
  3. Transthoracic echocardiographyAnswer
  4. D
    Magnetic resonance imaging of the brain and spinal cord
  5. E
    Fasting blood glucose and hemoglobin A1c

Answer

Transthoracic echocardiography is the most appropriate investigation to evaluate for hypertrophic cardiomyopathy, which is the leading cause of mortality in patients with Friedreich ataxia.
The patient's clinical picture is classic for Friedreich ataxia, an autosomal recessive condition caused by a GAA trinucleotide repeat expansion in the FXN gene. This leads to degeneration of multiple spinal cord tracts (spinocerebellar, dorsal columns, corticospinal) and peripheral nerves. Characteristic findings include progressive ataxia, absent lower extremity reflexes, loss of proprioception/vibration, and skeletal abnormalities such as pes cavus and kyphoscoliosis. Up to 90% of patients develop hypertrophic cardiomyopathy, which can cause fatal arrhythmias or congestive heart failure. Because this cardiac involvement is the leading cause of mortality, an echocardiogram is the most critical step in evaluating long-term prognosis and directing appropriate cardiac care.

Step-by-Step Solution

1
Analyze the clinical presentation to establish the most likely diagnosis.
The combination of progressive ataxia, pes cavus, kyphoscoliosis, absent lower extremity reflexes, and sensory loss in a young patient with an affected sibling strongly suggests Friedreich ataxia.
Identifying the underlying autosomal recessive disorder is required before determining its associated complications.
2
Identify the primary life-threatening complication associated with this disease.
Hypertrophic cardiomyopathy is the leading cause of death in patients with Friedreich ataxia.
The question specifically asks for the investigation targeting the most common cause of mortality.
3
Select the appropriate diagnostic modality for the identified complication.
Transthoracic echocardiography is selected to evaluate for cardiac hypertrophy and dysfunction.
Echocardiography is the standard imaging modality to assess for hypertrophic cardiomyopathy.

Key Concept

Friedreich ataxia is an autosomal recessive neurodegenerative disorder characterized by progressive ataxia, loss of deep tendon reflexes, and skeletal deformities (pes cavus, kyphoscoliosis). The most common cause of death is hypertrophic cardiomyopathy, necessitating evaluation with echocardiography.
Estimated Time:1m 0s
Rate this question

Topics

Pediatric Neurologic Disorders

More questions from this topic