Understanding Foot Drop: Causes and Mechanisms

• Foot drop involves the inability to dorsiflex the foot.
• Foot drop results from weakness or paralysis of the dorsiflexor muscles.
• Key muscles affected include the tibialis anterior, extensor hallucis longus, and extensor digitorum longus.
• These muscles are innervated by the deep peroneal nerve, which is a branch of the common peroneal nerve.
• Lifting the front part of the foot becomes difficult for those with foot drop.
• Patients with foot drop experience difficulty lifting the foot, which leads to toe dragging while walking.

Etiology of Foot Drop

• Foot drop or the weakness of foot dorsiflexors arises from lesions that affect the L5 nerve root, lumbar plexus, sciatic nerve, or common peroneal nerve
• Common causes of foot drop:
  • Peroneal nerve injury
  • Multiple sclerosis
  • Stroke
  • Lumbar radiculopathy/sciatica
  • Parkinson's disease
  • Cerebral palsy
  • Myositis/Muscular dystrophy
  • Polio
• Neurological causes are the most common:
  • Peripheral nerve disorders
  • Peroneal nerve injury occurs due to trauma, crossing legs, or surgery.
  • Central nervous system disorders
  • Stroke, multiple sclerosis, cerebral palsy, or motor neuron disease (ALS, polio).
• Muscular causes include:
  • Muscular dystrophy
  • Genetic muscle weakness.
  • Myopathies
  • Inflammatory motor disease (e.g., polio myositis).
• Anatomical & structural causes:
  • Trauma, such as pelvic, hip, or knee fracture.
  • Tumors/masses
  • Nerve compression.
  • Compartment syndrome
  • Increased muscle pressure, which damages the nerves.
• Metabolic & systemic causes:
  • Diabetes causes nerve damage (diabetic neuropathy).
  • Vitamin B12 deficiency & alcoholism lead to peripheral neuropathy.

Classifications of Foot Drop

• Neurological Classification: Based on Nerve Damage
• Anatomical Classification: Based on Location of Damage
• Clinical Classification: Based on Severity

Neurological Classification: Based on Nerve Damage

• Upper Motor Neuron Foot Drop is caused by brain or spinal cord damage (e.g., stroke, multiple sclerosis).
• Lower Motor Neuron Foot Drop is caused by peripheral nerve damage (e.g., peroneal nerve injury, lumbar radiculopathy).

Anatomical Classification: Based on Location of Damage

• Central Causes: Issues in the brain or spinal cord
• Peripheral Causes: Damage to the peripheral nerves such as the peroneal nerve.

Clinical Classification: Based on Severity

• Mild: Weak foot movement with normal walking.
• Moderate: Difficulty lifting the foot, leading to tripping.
• Severe: Complete inability to lift the foot, requiring assistive devices.

Conditions Leading to Foot Drop.

• Peroneal nerve injury caused by compression of trauma affecting nerve function
• Lumbar radiculopathy: Nerve root compression in the lumbar spine.
• Charcot-Marie-Tooth Disease is a hereditary neuropathy that causes progressive weakness
• Stroke & multiple sclerosis.
• These are neurological conditions that affect motor control.
• ALS (Amyotrophic Lateral Sclerosis): Progressive degeneration of motor neurons

Diagnosis of Foot Drop

• Subjective history should emphasize any trauma, recent spinal or limb surgery, and family history.
• Clinical examination includes: -Gait analysis -Muscle strength tests -Reflex and sensation exams
• Nerve and muscle tests -Electromyography to measure electrical activity in muscles.
• Nerve conduction studies check how well electrical signals travel through the peroneal nerve
• Image testing: -MRI to check for nerve compression, herniated discs, or brain and spinal cord issues,.
• CT scans, ultrasound or X-rays to check for nerve damage

Management of Foot Drop

• The treatment depends on the cause, with the main goals to improve mobility, prevent complications, treat root causes, and address pain
• Conservative Management: Braces and orthotics, physiotherapy, and medications are management options.
• Surgical Management: Nerve surgeries, tendon transfer surgery, nerve decompression, etc
• Lifestyle and Home Care: This involves avoiding prolonged kneeling or crossing legs, using assistive devices if needed, and having regular check-ups.

Physiotherapy Management

• Exercise therapy helps rehabilitate foot drop patients
• It includes ankle dorsiflexion exercises, toe and heel raises, marble pick ups, ankle inversion and eversion, and assisted toe raises.
• Functional Electrical Stimulation (FES) devices apply electrical impulses to the dorsiflexor muscles, which promotes active foot lifting during ambulation
• Gait training: Supervised gait re-education with assisted devices enhances functional mobility.
• Orthotic support involves the use of ankle foot orthoses (AFOs) and drop foot braces to provide support & maintain foot position.
• Balance training: Single-leg stance and heel-to-toe walking to improves stability

Prognosis of Foot Drop

• It varies, depending on the underlying cause.
• Good prognosis includes traumatic or compressive neuropathy and temporary conditions.
• Variable prognosis involves neurodegenerative disease, diabetic neuropathy, stroke, and spinal cord injury.
• Poor prognosis includes congenital conditions and severe nerve damage.
• Proper treatment and rehabilitation can lead to significant improvement or recovery.