What bedside neurological screening should be performed for an adult (20‑70 years) presenting with low‑back pain?

Bedside Neurological Screening for Adults with Low Back Pain

For adults aged 20-70 presenting with low back pain, perform a focused neurological examination to identify red flags requiring urgent intervention—specifically assess for motor weakness, sensory deficits in a dermatomal pattern, reflexes, and signs of cauda equina syndrome. 1, 2

Essential Neurological Screening Components

Immediate Red Flag Assessment (Cauda Equina Syndrome)

• Assess for urinary retention or fecal incontinence 2
• Test for saddle anesthesia (perianal/perineal sensation loss) 2
• Check for bilateral leg weakness 2
• Any positive finding requires emergency MRI and surgical consultation within hours 1

Motor Examination

• Test hip flexion (L2-L3), knee extension (L3-L4), ankle dorsiflexion (L4-L5), and great toe extension (L5) 1, 3
• Assess ankle plantarflexion (S1) 3
• Document any weakness on a 0-5 scale 1
• Severe or progressive motor deficits warrant urgent imaging and specialist referral within 2 weeks 1

Sensory Examination

• Test light touch in dermatomal distributions: L4 (medial calf), L5 (dorsum of foot), S1 (lateral foot) 1, 3
• Sensory changes in the affected territory combined with radicular pain indicate radiculopathy requiring earlier specialist referral 1
• True radiculopathy presents with leg pain below the knee in a dermatomal distribution 2

Reflex Testing

• Check patellar reflex (L3-L4) and Achilles reflex (S1) 3, 4
• Asymmetric or absent reflexes suggest nerve root compression 4
• Document reflex findings as normal, diminished, or absent 3

Straight Leg Raise Test

• Perform with patient supine: raise leg passively while keeping knee extended 5
• Positive test reproduces radicular pain below the knee at <60 degrees elevation 5
• This suggests nerve root tension from disc herniation 5

Clinical Decision Algorithm Based on Findings

Normal Neurological Examination

• No imaging required initially 2, 6
• Proceed with conservative management for 4-6 weeks 2, 7
• Consider imaging only if no improvement after 6 weeks 7, 6

Radiculopathy Without Severe Deficits

• Sensory or motor changes in affected territory with radicular pain below the knee 1, 2
• Refer to specialist within 3 months (earlier if severe/disabling pain) 1
• Consider MRI if patient is surgical candidate or symptoms persist beyond 4-6 weeks 2, 6

Severe or Progressive Neurological Deficit

• Any progressive motor weakness, severe radicular pain preventing normal activities, or multiple nerve root involvement 1, 7
• Urgent referral within 2 weeks for imaging and specialist evaluation 1
• MRI is the imaging modality of choice 8, 4

Additional Screening for Serious Pathology

Age and Risk Factor Assessment

• Age >50 with unexplained weight loss or history of cancer: suspect malignancy 2, 8
• Older age, osteoporosis, chronic steroid use, or low-velocity trauma: suspect fracture 1, 2
• Fever, recent infection, IV drug use, or immunocompromised status: suspect infection 2, 7

Inflammatory Back Pain Screening (Age <45 with chronic pain >3 months)

• Morning stiffness >30 minutes 1
• Pain at night or early morning 1
• Improvement with exercise 1
• Consider HLA-B27 testing if inflammatory pattern present 1

Critical Pitfalls to Avoid

• Do not skip cauda equina assessment—this is a surgical emergency with permanent consequences if missed 2, 7
• Do not order routine imaging for nonspecific low back pain without red flags—it does not improve outcomes and leads to unnecessary interventions 2, 6
• Do not assume normal reflexes rule out radiculopathy—sensory and motor findings are more sensitive 3, 4
• Do not delay urgent referral for progressive neurological deficits—outcomes worsen with delayed intervention 1, 8