Ischemic Monomelic Neuropathy (IMN) is a rare but significant complication primarily associated with the creation of arteriovenous (AV) fistulas for hemodialysis access. IMN presents as acute pain, motor weakness, and sensory disturbances immediately following AV fistula surgery, without critical ischemia of the skin or muscles. Notably, the affected limb typically remains warm with palpable pulses. Early recognition and intervention are essential to prevent permanent neurological impairment.
IMN presents with the following distinct features:
Acute Onset of Pain: Severe limb pain appearing hours after AV fistula surgery.
Motor Weakness: Diffuse weakness or paralysis affecting multiple peripheral nerves, especially distally.
Sensory Changes: Numbness, paresthesia, or loss of sensation in areas supplied by median, ulnar, and radial nerves.
Warm Limb with Palpable Pulses: Unlike other ischemic conditions, pulses remain palpable, and the limb feels warm.
Absence of Skin or Muscle Necrosis: No signs of tissue necrosis, differentiating IMN from severe ischemic conditions.
Clawing of the Hand: Intrinsic muscle weakness may result in claw-hand deformity in severe cases.
Immediate Postoperative Onset: Symptoms appear immediately or within a few hours post-surgery.
Differential considerations include:
Vascular Steal Syndrome: Presents with coolness, pallor, and pain due to reduced hand blood flow, distinguishing it from the preserved pulses and warmth of IMN.
Peripheral Nerve Compression: Chronic conditions (e.g., carpal tunnel or ulnar neuropathy) cause localized deficits, unlike the acute and diffuse pattern seen in IMN.
Compartment Syndrome: Characterized by severe pain, swelling, and compromised distal pulses due to increased compartment pressures, differing from the typical presentation of IMN.
Postoperative Nerve Injury: Usually focal nerve deficits resulting from direct surgical trauma, without the diffuse neurological involvement seen in IMN.
Diagnosis is clinical, supported by:
Electromyography (EMG) and Nerve Conduction Studies (NCS): Demonstrate axonal loss (low amplitude or absent nerve responses), but conduction velocities are usually relatively preserved.
Doppler Ultrasonography: Typically normal arterial flow, helping differentiate IMN from other ischemic conditions.
Effective management centers on restoring adequate blood flow and includes:
Immediate Surgical Intervention: Early ligation or revision of the AV fistula improves neurological outcomes.
Pain Management: Adequate analgesia during acute presentation.
Physical Therapy: Early rehabilitation to maintain joint mobility and prevent contractures.
Close Monitoring: Frequent neurological assessments to guide ongoing management.
Patient Education: Informing patients about IMN symptoms to ensure early detection in future procedures.
Despite prompt management, persistent neurological deficits may occur. Preoperative risk assessment (diabetes, peripheral vascular disease) is critical to minimizing complications.