Clinical Scorecard: Combined Shunt Surgery and Lecanemab Treatment in Cases of Idiopathic Normal Pressure Hydrocephalus with Alzheimer's Disease: A Case Report

At a Glance

Key Highlights

• iNPH is comorbid with AD in approximately 25–67% of cases, necessitating simultaneous treatment approaches.
• Anti-amyloid-β therapies like lecanemab can cause amyloid-related imaging abnormalities (ARIA), raising concerns about perioperative bleeding risks during neurosurgical procedures.
• Two cases demonstrated safe and effective combined treatment with shunt surgery (LP or VP) and lecanemab without interruption of antibody therapy and without adverse events including ARIA.

Guideline-Based Recommendations

Diagnosis

• Use brain MRI to identify DESH findings (ventriculomegaly, enlarged Sylvian fissures, tightened sulci, callosal angle) for iNPH diagnosis.
• Perform tap test and cerebrospinal fluid (CSF) analysis including Aβ42/40 ratio to assess amyloid pathology and differentiate AD involvement.
• Assess cognitive function with MMSE, FAB, and Clinical Dementia Rating (CDR) scales.

Management

• Consider early initiation of anti-amyloid-β antibody therapy (e.g., lecanemab) for early-stage AD.
• Select shunt surgery type based on patient condition: LP shunt preferred when possible to reduce brain invasion and potential ARIA risk; VP shunt used when LP shunt contraindicated.
• Do not necessarily interrupt lecanemab therapy perioperatively; combined treatment can be safely administered with close monitoring.

Monitoring & Follow-up

• Monitor cognitive function longitudinally using MMSE and CDR scores.
• Perform imaging follow-up (MRI including FLAIR and T2 star-weighted sequences) to detect ARIA or hemorrhagic complications.
• Observe for clinical signs of gait disturbance, urinary incontinence, and behavioral changes.

Risks

• Potential for amyloid-related imaging abnormalities (ARIA) including microhemorrhages and superficial siderosis with anti-amyloid antibody therapy.
• Theoretical increased risk of perioperative intracranial bleeding during neurosurgical procedures in patients receiving anti-amyloid therapies.
• Need for careful surgical approach selection to minimize brain invasion and bleeding risk.

Patient & Prescribing Data

Elderly patients with comorbid iNPH and early-stage AD

Lecanemab therapy can be initiated early and continued safely alongside shunt surgery (LP or VP) without interruption; LP shunt may be preferred to reduce brain invasion and bleeding risk; cognitive improvements observed post-shunt surgery with continued antibody therapy.

Clinical Best Practices

• Diagnose comorbid iNPH and AD using combined imaging, CSF biomarkers, and cognitive assessments.
• Initiate lecanemab therapy early in AD while monitoring for ARIA.
• Choose shunt surgery type based on individual patient anatomy and comorbidities, favoring LP shunt when feasible.
• Coordinate timing of shunt surgery and antibody therapy to avoid interruption and minimize risks.
• Conduct thorough perioperative monitoring for neurological and imaging complications.

References

• Idiopathic normal pressure hydrocephalus and Hakim’s disease
• Amyloid-related imaging abnormalities in anti-amyloid antibody therapy
• Lecanemab clinical trials and early-stage Alzheimer's treatment