Developmental Delay: MCCQE1 Preparation Guide

Introduction

Developmental delay is a common presentation in pediatric practice and a high-yield topic for the MCCQE1. It refers to a child who fails to attain developmental milestones compared to peers of the same chronological age.

For MCCQE1 preparation, it is crucial to distinguish between:

• Developmental Delay: A lag in one or more developmental domains.
• Global Developmental Delay (GDD): Significant delay (usually defined as 2 or more standard deviations below the mean) in two or more developmental domains in children <5 years of age.
• Intellectual Disability (ID): A diagnosis reserved for children >5 years of age when IQ testing is reliable.

Developmental Domains

Assessment of development is typically divided into four major domains. A delay in one may impact others.

1. Gross Motor: Large muscle movements (sitting, walking).
2. Fine Motor & Vision: Small muscle movements (grasping, drawing) and visual coordination.
3. Speech & Language: Receptive (understanding) and Expressive (producing speech).
4. Social, Emotional & Cognitive: Interaction with others, problem-solving, and self-care.

Developmental Milestones

Memorizing milestones is essential for the MCCQE1. The Rourke Baby Record (RBR) is the gold standard surveillance tool used in Canada.

Red Flags for Referral

Immediate evaluation is required if these red flags are present. These are frequent targets for MCCQE1 decision-making questions.

Etiology and Risk Factors

The etiology of GDD is identifiable in approximately 50-70% of cases.

• Prenatal (Most Common): Genetic syndromes (Down, Fragile X), cerebral dysgenesis, toxins (Alcohol - FASD, TORCH infections).
• Perinatal: Hypoxic-ischemic encephalopathy (HIE), extreme prematurity, kernicterus.
• Postnatal: Infection (Meningitis), trauma (TBI), environmental deprivation, hypothyroidism.

Common Genetic Causes in Canada

1. Down Syndrome (Trisomy 21)
2. Fragile X Syndrome: Most common inherited cause of ID.
3. Fetal Alcohol Spectrum Disorder (FASD): Leading preventable cause of developmental delay in Canada.

Clinical Approach to Developmental Delay

Follow this step-by-step approach for your MCCQE1 clinical reasoning.

Canadian Guidelines & Management

Screening Tools

In Canada, surveillance is opportunistic during periodic health exams.

• Rourke Baby Record (RBR): Evidence-based health supervision guide used across Canada.
• Nipissing District Developmental Screen (NDDS) / Looksee: Parent-completed screening tool often used at 18 months.

Management Principles

1. Early Intervention: Do not “wait and see”. Refer to early intervention programs (physiotherapy, occupational therapy, speech-language pathology) immediately upon identification of delay, even before a specific diagnosis is made.
2. Multidisciplinary Team: Pediatrician, geneticist, developmental pediatrician, allied health.
3. Family Support: Financial support (Disability Tax Credit), respite care.

Key Points to Remember for MCCQE1

• Correction for Prematurity: Always correct until 2 years old.
• Regression: Always a medical emergency requiring urgent workup for metabolic or neurodegenerative disorders.
• Hearing & Vision: The most common reversible causes of “apparent” delay. Must be ruled out first.
• Language Delay: An 18-month-old with no single words needs an audiology referral.
• Autism Spectrum Disorder (ASD): Red flags include lack of joint attention, poor eye contact, and repetitive behaviors. M-CHAT screening is typically done at 18 and 24 months.
• Hand Dominance: Hand preference before age 18 months is abnormal and suggests hemiparesis on the contralateral side.

Sample Question

Case Presentation

A 15-month-old male is brought to the family physician for a well-child visit. The parents are concerned that he is not yet walking independently. He was born at 39 weeks gestation via uncomplicated vaginal delivery. He sits without support and crawls efficiently. He babbles and says “mama” and “dada” specifically. He points to objects he wants. He has a mature pincer grasp and can transfer objects. Physical examination reveals normal muscle tone, equal reflexes, and no dysmorphic features. His hips have full range of motion.

Which one of the following is the most appropriate next step in management?

Options

• A. Refer to pediatric neurology for MRI of the brain
• B. Order creatine kinase (CK) levels
• C. Reassess developmental milestones in 3 months
• D. Refer to physiotherapy immediately
• E. Order chromosomal microarray

Explanation

The correct answer is:

• C. Reassess developmental milestones in 3 months

Detailed Analysis: This clinical scenario describes a child with isolated gross motor delay (specifically not walking) but who is otherwise developing well.

• Assessment of the Scenario: The child is 15 months old. While many children walk by 12 months, the upper limit of normal for independent walking is 18 months. The child has good motor skills otherwise (sits, crawls, pincer grasp) and normal neurological exam (normal tone, reflexes). He also has normal language and social skills (pointing, specific words).
• Option A (MRI): Inappropriate. There are no focal neurological signs, microcephaly, or regression to warrant neuroimaging.
• Option B (CK): While Duchenne Muscular Dystrophy is a consideration in boys with motor delay, it typically presents with hypotonia or head lag. This child has normal tone and is crawling efficiently. CK might be considered if he is not walking by 18 months, but it is not the most appropriate next step at 15 months with a normal exam.
• Option C (Reassess): This is the correct answer. Since the child is within the normal range (up to 18 months) and has no red flags (e.g., hypertonia, hypotonia, asymmetry), watchful waiting with a planned follow-up is the standard of care.
• Option D (Physiotherapy): While rarely harmful, it is not strictly necessary as the child has not yet crossed the threshold for pathology (18 months).
• Option E (Microarray): This is a first-line test for Global Developmental Delay (delay in 2+ domains) or if dysmorphic features are present. This child has isolated gross motor delay without dysmorphism.

References

1. Canadian Paediatric Society (CPS). (2016, reaffirmed 2021). Global developmental delay and intellectual disability: Terminology, evaluation and management. Link to CPS Position Statement 
2. Rourke, L., Leduc, D., & Rourke, J. (2020). Rourke Baby Record: Evidence-based infant/child health maintenance guide. Link to Rourke Baby Record 
3. Choosing Wisely Canada. Paediatrics: Five Things Physicians and Patients Should Question. Link 
4. Medical Council of Canada. MCCQE Part I Objectives: Developmental Delay.
5. Michelson, D. J., et al. (2011). Clinical Report—Identification and Evaluation of Children With Global Developmental Delay or Intellectual Disability. Pediatrics.

# MCC Abbreviations Used
- **GDD:** Global Developmental Delay
- **ID:** Intellectual Disability
- **CMA:** Chromosomal Microarray
- **RBR:** Rourke Baby Record
- **FASD:** Fetal Alcohol Spectrum Disorder
- **ASD:** Autism Spectrum Disorder