Functional neurological symptoms in children — formative SAQs

SAQ 1 — Making a positive diagnosis and avoiding the investigation cascade (10 marks)

A 13-year-old presents with three weeks of a fluctuating, abnormal gait. Examination shows internally inconsistent weakness with a positive Hoover sign, non-dermatomal sensory loss split at the midline, and a gait that improves with distraction. An MRI brain and spine are normal. The family is anxious and asking for "more scans". [2] [13]

Questions

1. State the diagnostic principle at work and name three positive clinical signs that support the diagnosis. (3 marks) [2] [5]
2. Outline how you would communicate the diagnosis to the family, giving an example of validating and an example of harmful language. (3 marks) [2] [13]
3. Describe the definitive stepped management, naming first-line therapy and the role of investigation. (4 marks) [3] [5]

Model answer

Diagnostic principle (3). Functional neurological disorder is a positive diagnosis made from internally inconsistent or incongruent signs that are not better explained by another disorder — not a diagnosis of exclusion. Positive signs here include the Hoover sign (hip extension weakness resolving with contralateral hip adduction against resistance), non-dermatomal midline-split sensory loss, and a gait that improves with distraction. FND may coexist with organic disease, but here the signs and intact neuroanatomy make FND defensible. [2] [13]

Communication (3). Use validating language: "These symptoms are real. The signals between your brain and body have become disrupted, the nervous system is structurally intact, and this improves with rehabilitation." Name the diagnosis explicitly as functional neurological disorder. Avoid harmful language — "it's all in your head", "medically unexplained", "psychosomatic", "fake", "attention-seeking" — which fractures the alliance. Offer the family the plan and a named coordinator. [2] [13]

Stepped management (4). Step 1: communicate the positive diagnosis. Step 2: triage acuity, safety and comorbidity (mood, sleep, pain, safeguarding, school). Step 3: treat in parallel — physiotherapy-led functional rehabilitation is first-line for motor FND (retrain normal movement, graded activity, distraction, confidence), with psychological therapy for comorbid mood/anxiety. Step 4: graded, structured return to school with a written plan and relapse strategy. Step 5: follow up at two to four weeks then as needed, with a clear safety-net. Investigations are directed at specific differentials with an agreed stop-point — a repeated normal scan perpetuates harm. No drug treats FND itself. [3] [5] [9]

SAQ 2 — Dissociative seizures, iatrogenic harm and prognosis (10 marks)

A 12-year-old on three anti-seizure medications for "refractory epilepsy" has events with closed eyes resisting opening, non-rhythmic movements, gradual onset and recall. On the ward he is catheterised and given regular oral morphine for leg pain; the family is "doctor-shopping" for further opinions. [10] [2]

Questions

1. What is the most likely diagnosis, and what is the gold-standard confirmatory test? (3 marks) [10] [11]
2. Identify three iatrogenic perpetuating factors in this vignette and state the corrective action for each. (4 marks) [2] [3]
3. Which prognostic factors predict a poorer outcome, and what is the overall prognosis with timely care? (3 marks) [9] [12]

Model answer

Diagnosis and confirmation (3). The semiology is dissociative (psychogenic non-epileptic) seizures: closed eyes resisting opening, non-rhythmic/out-of-phase movements, gradual onset and recall. The gold-standard confirmation is video-EEG capturing a typical event that shows no electrographic change during the semiology. A routine interictal EEG, normal or not, neither confirms nor refutes PNES. [10] [11]

Iatrogenic perpetuators and correction (4). (a) Escalating anti-seizure drugs for events that are not epilepsy — review and taper under specialist guidance, treating proven epilepsy only if coexisting. (b) Urinary catheterisation and immobilisation — remove the catheter, mobilise through graded functional rehabilitation. (c) Regular oral morphine for functional pain — withdraw opioids, treat pain with non-opioid, function-focused strategies. Across all three, agree an investigation stop-point, deliver one consistent message, and assign a named coordinator to prevent doctor-shopping. [2] [3]

Prognosis (3). Poorer outcome is predicted by long duration, severe entrenched school absence, diagnostic delay with repeated investigations, family discord and multiple psychiatric comorbidities. The overall prognosis with timely, consistent, multidisciplinary care is favourable — most children improve substantially. School return and short symptom duration are the strongest favourable markers. [9] [12]