What is the best course of action for a 2.5-year-old patient with a history of constipation, vomiting, and recent development of an awkward, stiff gait, wide stance, poor coordination, and balance, with pronated ankles, after successful treatment of constipation with MiraLAX (polyethylene glycol 3350)?

Urgent Neurological Evaluation Required

This child requires immediate referral to pediatric neurology to evaluate for a neurological disorder causing the gait abnormality, as the constellation of chronic constipation, vomiting, and progressive development of ataxia, stiff gait, and poor coordination strongly suggests an underlying neurological condition rather than a complication of constipation alone.

Critical Red Flags Requiring Neurological Assessment

• The development of an awkward, stiff gait with wide stance, poor coordination, and balance problems in a 2.5-year-old represents cerebellar dysfunction or other central nervous system pathology that demands urgent evaluation 1
• Signs of cerebellar dysfunction such as ataxia may indicate conditions like Chiari malformation, posterior fossa abnormalities, or other structural brain lesions 1
• The combination of chronic gastrointestinal symptoms (constipation since 8 months, vomiting for 1 year) followed by progressive neurological deterioration suggests a systemic or neurological disorder rather than simple functional constipation 1
• Axial hypotonia with peripheral hypertonia and gait abnormalities can indicate neurodegenerative conditions, metabolic disorders, or structural CNS lesions 1

Specific Neurological Conditions to Consider

• Williams syndrome presents with neurologic problems including axial hypotonia, peripheral hypertonia with increased deep tendon reflexes in lower extremities, and signs of cerebellar dysfunction such as ataxia that may increase with age 1
• Joint contractures in older children can lead to an awkward gait in certain genetic syndromes 1
• Chiari malformation should be evaluated if symptoms of headache, dizziness, or dysphagia are present, as posterior fossa abnormalities can cause both cerebellar signs and gastrointestinal dysmotility 1
• Metabolic or neurodegenerative disorders can present with both chronic constipation and progressive neurological deterioration 1

Immediate Diagnostic Workup Needed

• Pediatric neurology consultation should include detailed neurological examination focusing on cerebellar signs, muscle tone abnormalities, deep tendon reflexes, and gait analysis 1
• Brain MRI with attention to posterior fossa structures, cerebellar volume, and evaluation for Chiari malformation is indicated given the cerebellar signs 1
• Genetic evaluation may be warranted depending on physical examination findings, particularly if dysmorphic features or other syndromic features are present 1
• Metabolic screening should be considered if neurodegenerative process is suspected 1

Continuation of Constipation Management

• Continue polyethylene glycol (PEG 3350) at the current effective maintenance dose of 0.8-1.1 g/kg/day to maintain soft, painless stools while the neurological evaluation proceeds 2, 3, 4, 5
• The goal remains achieving one non-forced bowel movement every 1-2 days 2
• Monitor for recurrence of fecal impaction, as neurological conditions affecting the enteric nervous system may predispose to ongoing constipation 1

Key Clinical Pitfall to Avoid

• Do not attribute the neurological symptoms to complications of constipation or assume they will resolve with continued bowel management alone - the temporal progression and specific pattern of cerebellar dysfunction demands primary neurological investigation 1
• The fact that constipation was successfully treated 8 weeks ago but neurological symptoms persist or developed afterward suggests these are not secondary to constipation but rather part of an underlying systemic condition 1