Inability to Great Toe Dorsiflexion: Evaluation and Management
Immediate Clinical Assessment
The inability to dorsiflex the great toe requires urgent evaluation to distinguish between peripheral nerve injury (most common), central neurological pathology, or vascular compromise—each demanding different management approaches. 1
Critical Initial Examination Steps
Evaluate for the "6 Ps" of acute limb ischemia immediately: pain, paralysis, paresthesias, pulselessness, pallor, and poikilothermia (cold extremity), as any delay in diagnosis increases risk of amputation and death. 1
Check bilateral pedal pulses and ankle-brachial index (ABI) if pulses are diminished or absent, as an ABI <0.90 confirms peripheral artery disease and ABI <0.3 represents severe ischemia requiring intervention within hours. 2, 3
Assess for upper versus lower motor neuron signs: hyperactive ankle reflexes, clonus, and Babinski sign indicate central pathology requiring brain/spine imaging, while isolated weakness with normal reflexes suggests peripheral nerve injury. 4, 5
Test extensor hallucis longus strength specifically (isolated great toe dorsiflexion) versus tibialis anterior (ankle dorsiflexion) to localize the lesion—isolated great toe weakness suggests L5 radiculopathy or deep peroneal nerve injury. 6
Palpate for a palpable gap or compartment tension in the anterior leg, as compartment syndrome can cause irreversible muscle damage within 4-6 hours if pressures exceed 45 mmHg. 6
Diagnostic Algorithm Based on Clinical Findings
If Vascular Compromise Suspected (Cold Foot, Absent Pulses, Acute Onset)
Initiate systemic anticoagulation with intravenous unfractionated heparin immediately to prevent thrombus propagation while awaiting imaging. 1
Obtain CT angiography (CTA) of the entire lower extremity emergently as the preferred initial imaging modality, providing rapid comprehensive anatomic detail for revascularization planning within hours. 1
Consult vascular surgery immediately before imaging completion, as patients with motor deficits (Rutherford Class IIb) require intervention within 6 hours to prevent permanent tissue damage. 1
Do not delay for ankle-brachial index measurement, as ABI only confirms arterial occlusion but provides no information about location or treatment planning needed in acute limb ischemia. 1
If Upper Motor Neuron Signs Present (Hyperreflexia, Clonus, Bilateral Involvement)
Obtain urgent brain and spine MRI to evaluate for stroke, demyelinating disease, or traumatic injury affecting the motor cortex or corticospinal tracts. 4
Central foot drop is more spastic in nature and may present with bilateral involvement, distinguishing it from peripheral causes. 4
Treatment should be directed at the underlying central pathology rather than the foot drop itself. 4
If Peripheral Nerve Injury Suspected (Normal Reflexes, Unilateral, Trauma History)
Evaluate for common peroneal nerve injury at the fibular head (most common cause) versus L5 radiculopathy—peroneal nerve injury affects both ankle and toe dorsiflexion, while L5 radiculopathy may spare ankle dorsiflexion if tibialis anterior is intact. 4, 5
Obtain nerve conduction studies and EMG if diagnosis is unclear or to confirm the level and severity of nerve injury. 5
Check for recent tibial osteotomy or knee surgery, as common peroneal nerve injury is a recognized complication even with normal compartment pressures. 6
If Diabetic Patient with Chronic Onset
Perform comprehensive diabetic foot examination including 10-g monofilament testing at three standardized sites on each foot, with protective sensation present if patient correctly answers two out of three applications per site. 7
Test vibration sense with 128-Hz tuning fork applied perpendicularly to the dorsal distal phalanx of the great toe, as loss of vibration sense indicates large-fiber neuropathy. 2, 7
Assess for loss of protective sensation (LOPS) using monofilament testing plus at least one other assessment (pinprick, temperature, vibration, or ankle reflexes)—absent monofilament sensation suggests LOPS and significant ulceration risk. 2
Inspect for foot deformities, ulcers, and Charcot foot, as patients with motor weakness and sensory loss require specialized therapeutic footwear and multidisciplinary foot care. 2
Common Pitfalls to Avoid
Do not assume peripheral nerve injury without checking pulses and vascular status, as acute limb ischemia with motor deficits requires revascularization within 6 hours, not conservative management. 1
Do not order duplex ultrasound as the initial test for suspected acute limb ischemia, as it is too time-consuming, operator-dependent, and cannot provide comprehensive anatomic mapping needed for emergency revascularization planning. 1
Do not apply monofilament testing directly on calluses, scars, or ulcer sites, and ensure the patient cannot see where the filament is applied to avoid false-positive results. 7
Do not delay imaging if compartment syndrome is suspected, as clinical examination alone may miss elevated compartment pressures, and fasciotomy must be performed urgently if pressures exceed 45 mmHg. 6
Specific Management Based on Etiology
Acute Limb Ischemia with Motor Deficit
Proceed to urgent endovascular or surgical revascularization based on CTA findings, with catheter-directed thrombolysis or mechanical thrombectomy preferred for acute occlusions. 1
- Initiate dual antiplatelet therapy or rivaroxaban 2.5 mg twice daily plus aspirin 100 mg daily after successful revascularization to reduce major adverse limb events. 1
Peripheral Nerve Injury
Conservative management with ankle-foot orthosis (AFO) for foot drop, with surgical exploration considered if no recovery after 3-6 months or if nerve transection is suspected. 5
Diabetic Neuropathy with Foot Drop
Refer to foot care specialist for ongoing preventive care and provide specialized therapeutic footwear for patients with severe neuropathy and foot deformities. 2
- Optimize glycemic control with HbA1c <7% to prevent progression of neuropathy and improve limb outcomes. 1