REFERENCE · UNDERSTANDING DIAGNOSIS
What Tests and Investigations Can Tell Us
For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources
For the Person With FND
An investigation is most useful when it answers a question. A scan may assess a suspected brain or spinal problem; a nerve study asks a different question about peripheral nerve or muscle function. Which tests are appropriate depends on the history and examination. FND assessment can include investigations for another condition while also identifying positive functional signs. [1]
Ask, “What are we looking for with this test, and how would the result change the plan?” That can make a long series of unfamiliar appointments easier to understand.
A normal result needs interpretation within the test’s scope. An abnormality also needs interpretation: some findings are incidental, meaning they may not explain the symptom being investigated. Your clinician should explain whether a result fits the location, timing and pattern of your difficulty. [1]
If a new or substantially different symptom appears, tell the care team. An earlier functional diagnosis should not replace assessment of a new problem. Use urgent medical help for emergency symptoms rather than waiting for a planned outpatient test.
For the specific questions raised by arm or leg weakness, return to functional limb weakness.
For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources
For Family, Friends, and Other Supporters
Help keep results and appointment questions together if the person wants this. Check what follow-up has been agreed and who will explain the result.
Avoid concluding that “normal” means nothing is wrong or that any abnormal result must explain everything. You can help by asking what the result means for this person’s next steps.
For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources
For Clinicians and the Care Team
Define the clinical question before ordering or interpreting an investigation. Relate findings to phenotype and examination; preserve the possibility of coexisting disease. A negative investigation and a positive FND sign provide different kinds of information. [1]
Explain likely next steps before testing and record who will communicate the result. Select investigations according to clinical indications; this page is not a universal panel or a reason to repeat completed tests without a new question. Explicitly distinguish diagnostic work-up from evaluation of functional impact.
For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources
Research and Sources
This is an explanation of investigation scope based on a general clinical review. It does not prescribe a testing pathway for every FND presentation or validate an individual scan, blood test or electrophysiological result.
| Citation | Figure | Full citation and scope |
|---|---|---|
| [1] | — | Bennett K, Diamond C, Hoeritzauer I, Gardiner P, McWhirter L, Carson A, Stone J. A practical review of functional neurological disorder (FND) for the general physician. Clinical Medicine. 2021;21(1):28–36. https://doi.org/10.7861/clinmed.2020-0987 FND-CIT-0001. |
For the Person With FND
For Family, Friends, and Other Supporters
For Clinicians and the Care Team
Research and Sources