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Difficulty: MediumPediatric Neurologic Disorders

A 24-month-old girl is brought to the pediatric neurology clinic by her parents due to a 2-week history of abnormal eye movements and severe unsteadiness. The parents report that she has sudden, erratic eye movements and frequent jerky movements of her trunk and extremities. She was previously walking independently but now refuses to walk. Past medical history is notable for a viral upper respiratory infection associated with diffuse wheezing last month. She was also seen in the urgent care clinic 48 hours ago for a fever; a urine culture from that visit just returned positive for Escherichia coli that is sensitive to ampicillin, cephalexin, and trimethoprim-sulfamethoxazole. Recent routine laboratory screening revealed a low total thyroxine (T4) level with a normal thyroid-stimulating hormone (TSH) level. During the interview, the parents express profound anxiety about her neurocognitive development, specifically noting that she is unable to ride a tricycle or speak in 3-word sentences. Physical examination reveals an alert toddler. Neurologic examination is significant for continuous, chaotic, multi-directional conjugate eye movements. She has generalized myoclonus and severe truncal ataxia. Palpation of the abdomen reveals a firm, non-tender mass in the right upper quadrant. Based on the clinical presentation and physical examination findings, what is the most appropriate next step in the management of this patient?

  1. A
    Diagnose primary hypothyroidism and initiate oral levothyroxine supplementation
  2. B
    Initiate broad-spectrum intravenous meropenem for the urinary tract infection
  3. Order a computed tomography scan of the abdomen and pelvisAnswer
  4. D
    Diagnose developmental delay and refer for comprehensive early intervention
  5. E
    Diagnose pediatric asthma and prescribe a daily inhaled corticosteroid

Answer

Order a computed tomography scan of the abdomen and pelvis
This patient's presentation of rapid, multi-directional conjugate eye movements (opsoclonus), myoclonus, and ataxia is classic for opsoclonus-myoclonus syndrome (OMS). In children, OMS is most commonly a paraneoplastic manifestation of neuroblastoma, which is strongly supported by her palpable right upper quadrant abdominal mass. The most appropriate next step in management is cross-sectional imaging, such as a computed tomography (CT) scan of the abdomen and pelvis, to identify and characterize the suspected tumor.

Step-by-Step Solution

1
Analyze the neurologic findings of continuous, chaotic eye movements, myoclonus, and severe truncal ataxia.
These classic 'dancing eyes, dancing feet' findings represent opsoclonus-myoclonus syndrome (OMS).
Recognizing this specific neurologic syndrome is essential for identifying its underlying etiology.
2
Synthesize the OMS diagnosis with the physical exam finding of a firm, non-tender right upper quadrant abdominal mass.
The combination strongly suggests a paraneoplastic syndrome secondary to an intra-abdominal neuroblastoma.
Neuroblastoma is the most common extracranial solid tumor in children and frequently presents with paraneoplastic OMS.
3
Determine the most appropriate initial diagnostic modality to evaluate a suspected abdominal neuroblastoma.
A CT or MRI scan of the abdomen and pelvis is indicated.
Cross-sectional imaging is required to visualize the primary tumor, assess its extent, and plan for biopsy and definitive treatment.

Key Concept

Opsoclonus-Myoclonus Syndrome (OMS) as a paraneoplastic manifestation of Neuroblastoma
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Topics

Pediatric Neurologic Disorders

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