| Diplopia | symptom of seeing double, or double vision |
| Dura Mater | the tough outer covering of the brain. Lies below the skull. |
| Dysequilibrium | inability to maintain proper balance. Often noted as stumbling or falling to one side. |
| Dysesthesia | an unpleasant sensation. A symptom of pins and needles or tingling when skin is touched. |
| Dysphagia | inability to swallow properly. Often leads to aspiration. |