ToolsCalculators
Therapy-Disability-Neurology (TDN) Grade
Multidimensional grading of adverse events after cranial or spinal neurosurgery.
Therapy-Disability-Neurology (TDN) Grade
Therapy required for the adverse event
Disability (functional impact)
New neurologic deficit
ResultTDN Grade 1
The TDN grade equals the worst of the Therapy, Disability, and Neurology dimensions.
- Therapy grade
- T1
- Disability grade
- D1
- Neurology
- N1 (no new deficit)
- Overall TDN grade
- Grade 1
When to use
- Standardised reporting/grading of adverse events after cranial or spinal neurosurgical procedures for audit, quality improvement, or research.
Formula
The TDN grade is the worse (higher) of three ordinal dimensions, each graded 1-5: Therapy (T1-T5, based on the Clavien-Dindo/Landriel-Ibanez treatment-intensity classification), Disability (D1-D5, based on the modified Rankin Scale), and Neurology (N1=no new deficit, N2=any new neurologic deficit, capping at grade 2). Grade 5 adverse events always correspond to T5D5N2.
Pearls and pitfalls
- Extends therapy-based systems (e.g. Clavien-Dindo/Landriel-Ibanez) by also capturing disability and new neurologic deficits that may occur without any specific treatment.
- A new neurologic deficit (N2) alone - even without any treatment or measurable disability - is sufficient to raise the overall grade to at least 2.