A 34-year-old woman with no previous medical history presented with bilateral lower limbs weakness and numbness for three months. It was progressively worsening that she required wheelchair for ambulation in the last month. Neurological examination revealed bilateral foot drop with mild pedal oedema. There was symmetrical distal muscle weakness of the lower limbs with ankle dorsiflexion of 1/5, plantar flexion of 3/5, knee and hip flexion and extension of 4/5. Deep tendon reflexes were absent at the ankles and normal at the knees.