What is the diagnosis and treatment for a patient with a mute plantar response and a positive Hoover sign, suggesting a possible upper motor neuron lesion?

Functional Neurological Disorder (Conversion Disorder)

A mute (absent) plantar response combined with a positive Hoover sign indicates functional weakness (conversion disorder), not an upper motor neuron lesion. This combination is a classic presentation of functional neurological disorder (FND), where the positive Hoover sign demonstrates the functional nature of the weakness while the absent plantar response confirms the lack of true pyramidal tract pathology 1, 2, 3.

Understanding the Clinical Signs

Hoover Sign Interpretation

• Hoover sign is positive in functional weakness: During voluntary hip extension of the "weak" leg, there is no effort, but when the patient flexes the contralateral hip against resistance, involuntary hip extension occurs on the affected side 2, 3.
• The sign has moderate sensitivity (63%) but very high specificity (100%) for functional weakness, making it highly reliable when positive 2, 3.
• The sign is diagnosed using positive clinical signs, not as a diagnosis of exclusion, and can coexist with other neurological conditions 1.

Plantar Response Significance

• A mute (absent) plantar response excludes upper motor neuron pathology: True UMN lesions produce extensor plantar responses (Babinski sign), not absent responses 4, 5.
• Upper motor neuron lesions cause spasticity, hyperreflexia, and extensor plantar responses, while lower motor neuron lesions cause flaccidity and hyporeflexia 4.
• The absence of an extensor plantar response with positive Hoover sign confirms functional etiology rather than organic pyramidal tract disease 1, 2.

Diagnostic Approach

Clinical Examination Priorities

• Assess for other positive signs of functional weakness: Look for distractibility, entrainment of tremor, and variability in symptoms during function 1.
• Examine for true UMN signs that should be absent in FND: Check for spasticity, sustained clonus, and true hyperreflexia, which would suggest organic disease 4, 6.
• Test for inconsistencies in weakness patterns: Functional weakness typically shows give-way weakness, inconsistent effort, and improvement with distraction 1.

Investigations to Consider

• Neuroimaging (MRI brain and spine) may be appropriate initially to exclude structural mimics, though FND is a clinical diagnosis based on positive signs 1, 5.
• Electromyography is NOT indicated for pure functional weakness without fasciculations or atrophy, as it will be normal and does not contribute to diagnosis 4, 7.
• Do not pursue extensive investigations once FND is confidently diagnosed, as this reinforces illness behavior and delays appropriate treatment 1.

Treatment Recommendations

Core Therapeutic Interventions

• Occupational therapy is the cornerstone of treatment: Focus on physical rehabilitation through guided activity practice, supporting self-management, and developing an internal locus of control 1.
• Provide clear explanation of the diagnosis: Acknowledge that FND is real, common, and disabling with symptoms outside the person's control, caused by reversible miscommunication between brain and body 1.
• Emphasize that diagnosis is made by positive clinical signs (Hoover's sign, distractibility) and is not a diagnosis of exclusion 1.

Self-Management Strategies

• Support the patient to take ownership of rehabilitation: Use interactive workbooks or therapy journals to facilitate self-management and reduce dependency 1.
• Implement a 24-hour approach to therapy: Integrate rehabilitation strategies throughout daily routine rather than limiting to therapy sessions 1.
• Address symptom focus and attention: Discuss how self-directed attention worsens symptoms while redirecting attention can temporarily reduce them 1.

Addressing Comorbidities

• Provide practical management of pain and fatigue: These commonly coexist with FND and require integrated treatment 1.
• Support mental health problems: Chronic health conditions and symptom focus can exacerbate cognitive difficulties, fatigue, anxiety, low mood, and pain 1.
• Consider vocational rehabilitation: Help employers understand genuine symptoms with variable severity and advocate for reasonable adjustments 1.

Critical Pitfalls to Avoid

• Do not misinterpret positive Hoover sign as malingering: FND involves genuine symptoms outside voluntary control, not deliberate fabrication 1, 2.
• Avoid over-investigation once diagnosis is established: Excessive testing reinforces illness behavior and delays appropriate rehabilitation 1.
• Do not provide adaptive equipment prematurely: Equipment can cause secondary problems (joint pain, deconditioning) and increase dependency; consider each case individually 1.
• Recognize that sensory symptoms should prompt reconsideration: Pure motor neuron disease does not involve sensory pathways, so sensory complaints support functional diagnosis 4, 5.