What is the best course of action for a 52-year-old male (YOM) with Down syndrome experiencing acute onset of severe mobility issues, decreased weight-bearing ability, and potential pain, over the last week, worsening over the last 3 days?

Immediate Emergency Department Evaluation for Acute Spinal Cord Compression

This patient requires immediate cervical spine imaging (X-ray or CT) to rule out atlantoaxial instability with spinal cord compression, which is a life-threatening emergency in Down syndrome patients presenting with acute loss of ambulation. 1

Critical First Steps

Immediate Neck Immobilization

• Immobilize the cervical spine immediately before any further movement or examination 1
• Atlantoaxial dislocation in Down syndrome can cause spinal cord compression presenting as inability to walk, quadriparesis, and cervical myelopathy 1
• This patient's acute loss of weight-bearing ability over 3 days with baseline ability to move legs while supine is highly concerning for this diagnosis 1

Urgent Imaging Protocol

• Obtain cervical spine X-rays (lateral view with flexion/extension if stable) or CT cervical spine emergently 1, 2
• Do not delay imaging for other workup when atlantoaxial instability is suspected 1
• Radiological examination of the neck must occur before any intervention under general anesthesia in Down syndrome patients 2

Key Clinical Features Supporting This Diagnosis

Classic Presentation Pattern

• Acute onset inability to walk is the hallmark presentation of symptomatic atlantoaxial dislocation 1
• The patient can move legs while lying down but cannot weight-bear—this dissociation suggests upper motor neuron pathology rather than lower extremity joint/muscle problem 1
• Verbalization of pain ("owww") that is abnormal for this patient supports neck pain, a cardinal symptom 1
• The 3-hour toilet episode may represent urinary retention from cervical myelopathy 1

Down Syndrome-Specific Risk

• Atlantoaxial instability occurs with significant frequency in Down syndrome due to ligamentous laxity 2
• Adults with Down syndrome have muscular hypotonia and altered connective tissue that predispose to this complication 2
• This is a potentially fatal complication that requires immediate recognition 1

Differential Considerations After Spine Cleared

If cervical spine imaging is negative, rapidly evaluate for:

Orthopedic Causes

• Hip fracture or dislocation (can occur with minimal trauma due to ligamentous laxity) 2
• Pelvic imaging (X-ray pelvis/hips) 3
• Lower extremity long bone fractures 3

Neurological Causes Beyond Spine

• Acute stroke (though less likely given ability to move legs when supine) 4
• Cauda equina syndrome (though atlantoaxial is more likely given Down syndrome) 1

Medical Causes

• Severe infection causing weakness (respiratory or gastrointestinal, which are common in Down syndrome) 2
• Hypothyroidism exacerbation (occurs in up to 50% of adults with Down syndrome) 2
• Obstructive sleep apnea complications (occurs in ~50% of Down syndrome adults) 2

Immediate Management Priorities

While Awaiting Imaging

• Keep patient supine with cervical immobilization 1
• Avoid any neck manipulation or movement 1
• Monitor neurological status closely for progression 1
• Assess for urinary retention (bladder scan) given prolonged toilet episode 1

If Atlantoaxial Instability Confirmed

• Immediate neurosurgical consultation for cervical fusion (C1-C2) 1
• Continue strict cervical immobilization 1
• Admit to monitored setting 1
• Surgical repair with fusion can be performed after stabilization 1

Critical Pitfalls to Avoid

• Do not attribute acute mobility loss to behavioral changes or dementia without ruling out structural causes first 2
• Do not assume pain complaints are unreliable because patient is nonverbal at baseline—the caregiver's report of abnormal pain vocalization is highly significant 1
• Do not perform lumbar puncture or other procedures requiring positioning before clearing the cervical spine 1, 2
• Recognize that mobility impairment in this population carries 70% fall risk within 6 months and 2.3-fold increased disability risk, making urgent diagnosis essential 3

Long-Term Considerations

• If atlantoaxial instability is confirmed, this patient will require cervical fusion surgery 1
• All adults with Down syndrome should have had cervical spine screening, but many have not 2
• Annual medical check-ups are recommended for adults with Down syndrome to screen for multiple comorbidities 2
• Early physical therapy after resolution can help restore mobility and prevent deconditioning 5, 4