Neurology · Neurosurgery

Therapy-Disability-Neurology Grade calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Therapy level

Therapy follows treatment intensity. Death from the event is level 5.

Disability worsened by the event

Count disability only when the event made it worse than before surgery. Rankin 6 is death.

New neurologic deficit from the event

Count neurology only when the event caused the change. No new deficit does not raise the grade.

Result

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Primary source

Terrapon APR, Sarnthein J, Stienen MN, et al. Adverse events in neurosurgery: the novel Therapy-Disability-Neurology grade. Neurosurgery. DOI: 10.1093/neuros/nyab121. PMID: 33887774. Table definitions, confirmed in the open reprint of that table (Scientific Reports 2025, DOI: 10.1038/s41598-025-21065-8, Table 1): the grade equals the worse dimension. Therapy follows Clavien-Dindo I to V: T1 no treatment beyond antiemetics, antipyretics, analgesics, diuretics, electrolytes, physiotherapy, or bedside opening of a wound infection; T2 drug treatment including transfusion or parenteral nutrition; T3 an invasive procedure; T4 intensive care for a life-threatening event; T5 death. Disability, counted only when the event worsened it from the preoperative state, follows modified Rankin groups: D1 is 0 to 1, D2 is 2 to 3, D3 is 4, D4 is 5, and D5 is 6. Neurology is N1 no new deficit or N2 any new deficit, and it is counted only when the event caused the change. The printed example T3D4N1 is grade 4. A grade 5 event is always grade 5. (2021)

Scope: Neurosurgical adverse events. Disability and neurology are omitted when the event did not worsen them. Death from the event is grade 5.

Last reviewed 2026-10-17

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Professional use only

For qualified clinicians. Independently verify inputs, calculations, source guidance, and applicability before any clinical action. This calculator does not replace clinical judgment.

Source: Terrapon APR, Sarnthein J, Stienen MN, et al. Adverse events in neurosurgery: the novel Therapy-Disability-Neurology grade. Neurosurgery. DOI: 10.1093/neuros/nyab121. PMID: 33887774. Table definitions, confirmed in the open reprint of that table (Scientific Reports 2025, DOI: 10.1038/s41598-025-21065-8, Table 1): the grade equals the worse dimension. Therapy follows Clavien-Dindo I to V: T1 no treatment beyond antiemetics, antipyretics, analgesics, diuretics, electrolytes, physiotherapy, or bedside opening of a wound infection; T2 drug treatment including transfusion or parenteral nutrition; T3 an invasive procedure; T4 intensive care for a life-threatening event; T5 death. Disability, counted only when the event worsened it from the preoperative state, follows modified Rankin groups: D1 is 0 to 1, D2 is 2 to 3, D3 is 4, D4 is 5, and D5 is 6. Neurology is N1 no new deficit or N2 any new deficit, and it is counted only when the event caused the change. The printed example T3D4N1 is grade 4. A grade 5 event is always grade 5. (2021)

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Clinical inputs

Therapy level
Disability worsened by the event
New neurologic deficit from the event

Primary source

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