NASCIS II and NASCIS III: Full Overview

Background - What is NASCIS?

NASCIS I (1984) - Foundation

• Compared low-dose MPSS (100 mg bolus + 25 mg q6h x 10 days) vs. high-dose MPSS (1,000 mg bolus/day x 10 days)
• n = 330 patients; follow-up to 1 year
• Result: No difference in motor or sensory outcomes between groups
• Lacked a placebo arm - this was a major limitation

NASCIS II (1990)

Design

• n = 487 patients with acute blunt SCI
• Three arms:
  1. High-dose methylprednisolone (MPSS)
  2. Naloxone (opioid receptor antagonist)
  3. Placebo
• Treatment window: within 12 hours of injury (later narrowed)

MPSS Dosing Protocol (NASCIS II)

Primary Outcome

• The overall trial was negative - no statistically significant improvement in the primary analysis across the whole cohort.

Key Finding (Post-hoc Subgroup Analysis)

• Patients who received MPSS within 8 hours of injury showed modest but statistically significant improvements in motor function and sensation at 6 weeks and 6 months compared to placebo.
• Patients treated after 8 hours showed no benefit and possibly worse outcomes.
• Critically, the placebo group treated within 8 hours had similar early recovery to the MPSS group, and the benefit was not sustained to 1 year in all analyses.

Recommendation from NASCIS II

• MPSS within 8 hours of blunt SCI became widely adopted as standard practice globally based on this post-hoc finding.

NASCIS III (1997)

Design

• n = 499 patients at 16 North American centers
• All patients received MPSS 30 mg/kg IV bolus first, then randomized to:
  1. MPSS for 24 hours (5.4 mg/kg/h x 23h)
  2. MPSS for 48 hours (5.4 mg/kg/h x 47h)
  3. Tirilazad mesylate for 48 hours (2.5 mg/kg IV q6h)
• Treatment initiated within 8 hours of injury; drug administration goal within 6 hours
• Tirilazad is a 21-aminosteroid that inhibits lipid peroxidation without glucocorticoid receptor activation - it was investigated to get the neuroprotective benefit without steroid side effects.

Primary Outcome

• Again, the primary analysis was negative - no significant difference between the three groups overall.

Key Findings (Post-hoc Subgroup Analysis)

• Patients treated within 3 hours of injury: the 24-hour MPSS protocol was sufficient and optimal.
• Patients treated 3 to 8 hours after injury: the 48-hour MPSS protocol showed better motor recovery at 6 weeks and 6 months (not sustained to 1 year).
• Tirilazad was equivalent to the 24-hour MPSS protocol.

Complications Observed in NASCIS III

• Severe pneumonia
• Severe sepsis
• Wound infections and poor healing
• Pulmonary embolism and DVT
• GI bleeding
• Increased mortality from respiratory complications

Combined NASCIS II + III Recommendations (as originally derived)

Mechanism of Action of MPSS in SCI

1. Inhibition of lipid peroxidation by free radicals (main proposed mechanism)
2. Improved spinal cord blood flow
3. Prevention of potassium loss from injured tissue
4. Increased extracellular calcium stabilization
5. Interference with cytokine signaling and arachidonic acid metabolites
6. MPSS is preferred over other steroids because it crosses cell membranes more rapidly and completely

Criticisms and Controversies

• All positive findings were from post-hoc subgroup analyses - the primary analyses were negative
• The 3-hour and 8-hour time boundaries were considered artificial constructs
• Imbalanced injury severity between treatment groups
• Lack of meaningful functional outcome measures (motor score improvements were small and not clinically significant in daily life)
• The placebo group treated within 8h had similar early recovery, suggesting possible selection bias
• Complicated and criticized statistical methodology
• Statistical tools were "excessive, confusing, and difficult to replicate by professional statisticians" (Bradley & Daroff's Neurology in Clinical Practice)

Current Guidelines and Status

"There is no consistent or compelling medical evidence of any class to justify the administration of methylprednisolone for acute SCI. Methylprednisolone should NOT be routinely used."

• (Tintinalli's Emergency Medicine, p. 1755)

• A 24-hour high-dose MPSS infusion may be offered to patients presenting within 8 hours of injury (considered an option, not a standard)
• The 48-hour infusion should not be offered
• MPSS should not be given after 8 hours from injury
• (Current Surgical Therapy 14e; Rockwood & Green's 10th ed.)

Who Was EXCLUDED from NASCIS Trials (Cannot Apply Protocol)

• Penetrating spinal cord injuries (gunshot wounds)
• Nerve root injuries (cauda equina syndrome)
• Pregnant patients
• Age < 14 years
• Patients already on chronic steroids

Why MPSS Is Still Sometimes Used

• Fear of litigation - providers worry about liability if they don't give it
• Patient surveys show ~60% of SCI patients feel any small neurologic benefit is "very important" to them
• Persistence of older practice patterns

Summary Table

• Tintinalli's Emergency Medicine: A Comprehensive Study Guide, p. 1755
• Rockwood and Green's Fractures in Adults, 10th ed. 2025
• Current Surgical Therapy, 14th ed.
• Bradley and Daroff's Neurology in Clinical Practice
• Schwartz's Principles of Surgery, 11th ed.