What are the causes of bilateral closed fists?

Bilateral Closed Fists: Causes and Clinical Approach

Bilateral closed fists result from two distinct pathophysiologic mechanisms: upper motor neuron syndrome (spastic clenched fist deformity) or psychiatric/conversion disorder (clenched fist syndrome), and distinguishing between these is critical as their management differs fundamentally. 1, 2

Upper Motor Neuron Syndrome (Spastic Clenched Fist Deformity)

This is the most common organic cause of bilateral closed fists and results from brain or spinal cord injury affecting the corticospinal tracts. 1

Pathophysiology

• Develops from imbalance between extrinsic finger flexors and extensors, bringing fingers into flexed posture across metacarpophalangeal and interphalangeal joints 1
• Both extrinsic and intrinsic hand musculature contribute to the deformity, with intrinsic contributions sometimes masked by extrinsic flexors 1
• Severity varies based on involved muscle groups and degree of spasticity, myostatic contracture, and joint contractures 1

Associated Conditions Causing Bilateral Upper Motor Neuron Lesions

• Vitamin B12 deficiency causing subacute combined degeneration affecting bilateral corticospinal tracts, producing spastic paraparesis with hyperreflexia, spasticity, and extensor plantar responses 3
• Bilateral cerebral lesions affecting motor cortex or internal capsule, particularly parasagittal lesions affecting the leg area of motor homunculus 3
• Spinal cord lesions affecting bilateral corticospinal tracts 3

Clinical Features

• Upper motor neuron signs: hyperreflexia, spasticity, Babinski sign 3
• Markedly decreased hand function 1
• Hygiene difficulties with potential palm wounds from fingertip contact 1
• Fingers can be extended under anesthesia (distinguishing from fixed joint contractures) 4

Clenched Fist Syndrome (Psychiatric/Conversion Disorder)

This is a psychiatric disorder where no organic etiology can be identified, typically following minor trauma or inciting incident. 2, 4

Clinical Characteristics

• One or both hands held tightly clenched 4
• Associated with swelling, pain, and paradoxical stiffness 5, 4
• Usually follows minor inciting incident 4
• Extension of fingers is always possible under anesthesia 4
• No organic disease identifiable on examination or imaging 2, 4

Psychiatric Classification

• Considered either a conversion disorder (unconsciously motivated and produced) or factitious disorder (unconsciously motivated but consciously produced) 2
• Patients classified as having severe anger and poor defense mechanisms 4
• Psychiatric disease is frequent in these patients 6

Complications

• Severe forms may develop infections of palm or joints 5
• Hygienic problems can be considerable 6
• Patients may express strong wish for amputation 6
• Poor prognosis overall 4
• New contractures can develop after amputation (three of four amputated patients in one series developed new contractures) 6

Critical Diagnostic Distinctions

Rule Out These Conditions (They Do NOT Cause Bilateral Closed Fists)

• Cerebellar lesions: produce ataxia, dysmetria, and intention tremor—not spastic paraparesis, as cerebellum lacks upper motor neurons or corticospinal tracts 3
• Peripheral neuropathies: affect lower motor neurons producing flaccid weakness with hyporeflexia/areflexia, not spasticity and hyperreflexia 3
• Parkinson disease: basal ganglia disorder causing bradykinesia, rigidity, and tremor—not spastic paraparesis, without corticospinal tract involvement 3

Diagnostic Algorithm

1. Assess for upper motor neuron signs: hyperreflexia, spasticity, Babinski sign, clonus 3, 1
2. Obtain neurological examination to identify organic etiology 2
3. Perform spinal MRI to exclude myelopathy and other structural causes 3
4. Check vitamin B12 levels to exclude subacute combined degeneration 3
5. Obtain hand/wrist X-rays to exclude joint abnormalities 2
6. Evaluate under anesthesia if diagnosis unclear—fingers extend fully in clenched fist syndrome but may remain contracted in severe upper motor neuron syndrome with fixed contractures 4
7. Psychiatric evaluation if no organic cause identified 2, 6

Management Pitfalls

Surgical treatment is contraindicated in clenched fist syndrome (psychiatric) as it worsens symptoms, whereas it may be indicated for upper motor neuron syndrome with functional goals. 1, 2

• In upper motor neuron syndrome, surgical options include muscle-tendon lengthening, tenotomies, tendon transfers, muscle origin releases, and joint/ligament releases 1
• In clenched fist syndrome, surgery should be avoided entirely 2
• Amputation in clenched fist syndrome has particularly poor outcomes with high rates of new contracture development 6