What physical examination should be performed to evaluate a patient with right upper extremity weakness?

Physical Examination for Right Upper Extremity Weakness

Perform a systematic neurological and vascular examination that includes manual muscle testing with MRC grading, pulse palpation at all accessible sites, reflex assessment, and sensory testing to localize the lesion and determine urgency. 1, 2

Initial Assessment Components

Motor Examination

• Grade muscle strength using the Medical Research Council (MRC) scale (0=no contraction, 1=flicker, 2=movement without gravity, 3=movement against gravity, 4=movement against resistance, 5=normal strength) for all major muscle groups of the right upper extremity 3
• Test shoulder abduction and external rotation (C5-C6), elbow flexion (C5-C6), elbow extension (C7), wrist extension (C6-C7), finger extension (C7), finger flexion (C8), and intrinsic hand muscles (T1) 2, 4
• Document functional limitations in activities of daily living, self-care skills, writing, and computer use to assess real-world impact 3

Reflex Testing

• Assess deep tendon reflexes bilaterally including biceps (C5-C6), brachioradialis (C6), and triceps (C7) reflexes 2
• Hyperreflexia, spasticity, or a positive Babinski sign indicates upper motor neuron pathology requiring urgent brain and spine MRI 2
• Areflexia or hyporeflexia suggests lower motor neuron involvement, though the acute motor axonal neuropathy variant of Guillain-Barré syndrome may present with preserved or brisk reflexes despite ascending paralysis 2

Sensory Examination

• Test light touch, pinprick, temperature, vibration, and proprioception in dermatomal distributions 4
• Bilateral ascending paresthesias with weakness suggest Guillain-Barré syndrome, which requires immediate respiratory monitoring and hospitalization 2
• Dermatomal sensory loss helps localize cervical radiculopathy or peripheral nerve entrapment 4, 5

Vascular Assessment

Pulse Palpation

• Palpate and grade pulses bilaterally (0=absent, 1=diminished, 2=normal, 3=bounding) at the brachial, radial, and ulnar arteries 1, 6
• Asymmetric or absent pulses suggest vascular compromise requiring ankle-brachial index equivalent for upper extremities 1, 6

Blood Pressure Measurement

• Measure blood pressure in both arms to identify subclavian stenosis; a difference >15 mmHg is abnormal 1, 6

Inspection for Ischemic Signs

• Examine for skin pallor, cyanosis, temperature asymmetry, nail bed changes, and tissue loss 6
• In acute limb ischemia, assess for the "6 Ps": pain, pallor, pulselessness, paresthesias, paralysis, and poikilothermia 1
• Motor deficit indicates limb threat requiring emergency imaging and revascularization within 4-6 hours 1

Localization-Specific Maneuvers

Cervical Spine Assessment

• Bilateral hand dysfunction with fine motor impairment (inability to button a shirt) localizes to C5-C7 cord level and mandates urgent MRI 2
• Perform Spurling's test (neck extension with lateral flexion and axial compression toward the affected side) to reproduce radicular symptoms 4

Peripheral Nerve Testing

• Upper Limb Tension Test 1 (ULTT1) for median nerve: stabilize shoulder in abduction → extend wrist/fingers → supinate forearm → externally rotate shoulder → extend elbow → perform structural differentiation with contralateral neck side-bending 5
• Test should reproduce symptoms that increase with nerve stress and decrease with nerve relaxation 5
• Assess for Tinel's sign at common entrapment sites (thoracic outlet, cubital tunnel, carpal tunnel) 4

Neuromuscular Junction Testing

• Assess for fatigable weakness that worsens with repetitive use and improves with rest, suggesting myasthenia gravis 2
• Examine for ptosis, diplopia, and bulbar symptoms (dysarthria, dysphagia) 2

Critical Red Flags Requiring Urgent Evaluation

• Acute bilateral ascending weakness with areflexia: Guillain-Barré syndrome—measure vital capacity, negative inspiratory force, and maximal inspiratory/expiratory pressures using the "20/30/40 rule" to stratify respiratory failure risk 2
• Bilateral upper extremity involvement with upper motor neuron signs: obtain emergency brain and spine MRI to exclude stroke, cord compression, or transverse myelitis 2
• Motor deficit with absent pulses: acute limb ischemia requiring vascular surgery consultation within hours 1
• Dysautonomia (blood pressure or heart rate instability) with weakness: life-threatening complication of Guillain-Barré syndrome 2

Common Pitfalls to Avoid

• Do not delay spine MRI in patients with bilateral upper extremity weakness; postponement can result in irreversible paralysis 2
• Do not exclude Guillain-Barré syndrome based solely on normal reflexes; the AMAN variant may present with preserved reflexes 2
• Do not attribute weakness to deconditioning in older adults with vascular risk factors without objective vascular testing 6
• Physical examination findings alone are insufficient for diagnosis and must be confirmed with objective testing (nerve conduction studies, imaging, or vascular studies) 1, 2