Fig. 1

Checklist table. †Timepoint =  − t₁, baseline (before surgery); 0, allocation; t₁, surgery; t₂, within 72 h after surgery; t₃, at admission; t₄, 4–6 weeks after surgery; t₅, 6 months after surgery. *If reoperation has not been performed at 6 months postoperatively, imaging studies must be performed in patients with worsening neurological symptoms. Radiological imaging is not always necessary if the patient’s symptoms are stable