What is the appropriate next step in evaluation and management for a 52‑year‑old woman with intermittent right‑sided facial, arm and upper‑thigh sensory disturbances, left‑arm weakness and tremor, a negative MRI, and who was declined by neurology?

Appropriate Next Steps for Evaluation and Management

This patient requires immediate referral to a functional neurological disorder (FND) specialist or psychiatry with expertise in FND, as the presentation of non-anatomic sensory and motor symptoms crossing multiple vascular territories with a negative MRI strongly suggests a functional neurological disorder rather than structural disease. 1

Why Neurology Appropriately Declined

The neurology service correctly identified that this presentation does not follow any recognizable neuroanatomic pattern:

• Right-sided sensory disturbances affecting face, arm, and upper thigh cross multiple dermatomes and vascular territories (trigeminal nerve distribution, cervical roots, and lumbar roots) that cannot be explained by a single lesion 2
• Left arm weakness with trembling and impaired grasp combined with contralateral right-sided symptoms violates basic neuroanatomic principles 2
• Negative MRI excludes structural lesions such as stroke, demyelination, tumor, or spinal cord pathology that would be expected with these symptoms 3

Diagnostic Reasoning: Functional Neurological Disorder

The presentation is highly characteristic of FND based on modern diagnostic criteria:

• Positive diagnostic features include symptoms that do not conform to known neuroanatomic distributions, inconsistent examination findings (decreased ability to grasp but can perform other hand functions), and episodic nature with "trembling" 1
• FND is now diagnosed inclusively by identifying neurological signs specific to functional disorders, not by exclusion or requiring psychological stressors 1
• Normal neuroimaging does not exclude organic disease entirely but combined with non-anatomic symptoms makes FND the leading diagnosis 4, 1

Critical Next Steps

Immediate Actions Required

1. Refer to psychiatry or neurology with FND expertise for formal evaluation using validated diagnostic criteria and specific examination techniques that identify positive signs of FND 1

2. Perform targeted physical examination looking for:

   • Hoover's sign for leg weakness 1
   • Tremor entrainment or distractibility 1
   • Give-way weakness pattern 1
   • Non-dermatomal sensory loss 2, 1

3. Screen for predisposing factors including:

   • Recent physical trauma or medical illness 1
   • Physiological stressors or life events 1
   • History of other medically unexplained symptoms 1

Additional Diagnostic Considerations (If Red Flags Present)

Only pursue further organic workup if specific red flags emerge:

• Guillain-Barré syndrome: Would require bilateral symmetric weakness, areflexia, and ascending pattern—not present here 5, 6
• Multiple sclerosis: Would show lesions on MRI and follow specific anatomic pathways 3
• Stroke: Would cause sudden onset, contralateral deficits from unilateral lesion—not bilateral non-anatomic symptoms 5

Electrodiagnostic testing (EMG/NCS) can definitively exclude organic neuromuscular disease if diagnostic uncertainty persists, but should not delay FND-specific treatment 4, 6

Treatment Approach

Evidence-based treatment for FND includes:

• Physical rehabilitation with therapists trained in FND-specific techniques 1
• Psychological interventions including cognitive behavioral therapy 1
• Combination therapy showing most promise, though optimal duration remains under investigation 1
• Early diagnosis and treatment prevents iatrogenic harm from unnecessary testing and improves outcomes 1

Critical Pitfalls to Avoid

• Do not continue pursuing extensive organic workup without specific red flags, as this reinforces illness beliefs and delays appropriate treatment 4, 1
• Do not dismiss the patient's symptoms as "not real"—FND involves genuine neurobiological abnormalities in motor planning and sensory processing 1
• Do not wait for psychological stressors to be identified—modern criteria recognize FND can occur without identifiable psychological triggers 1
• Do not label as "malingering" without evidence of intentional symptom production for external gain—this is a diagnosis of exclusion requiring specific evidence 4