Functional Disorders

Exam Cram

• Functional disorders are where there is clear dysfunction, without objective signs on examination or investigations

• Common analogy: 'software problem' rather than 'hardware' (structural) problem, 

• Examples include: functional neurological disorders, IBS & fibromyalgia

• Diagnosis: usually clinical after excluding known conditions; management: supportive with lifestyle and symptom control

Overview

Definitions

• Functional pathology: a disease with no objective findings on investigations but significant symptom burden

• Psychological syndrome: a disorder of psychology

• Psychiatric pathology: a pathology located within the brain affecting emotion, thought, perception or cognition

• Symptom problem: a symptom without a diagnosis, i.e. a person presenting with a headache

• Medically unexplained symptoms: symptoms that are not attributable to a formal diagnosis, i.e. the majority of symptoms

• Diseases with psychological component

Psychological Syndromes

• Malingering- Consciously attempting to deceive for deliberate personal gain-> i.e. presenting with a limp for sick leave

• Factitious disorder- This is the same a Munchausen's syndrome, the key difference is that person does this for reassurance subconsciously.

• Munchausen syndrome- Same as factitious disorder: an individual is presents with a limp for reassurance. 

• Munchausen syndrome by proxy- This is where an individual states e.g. their child has a limp because they subconsciously like to be a care giver, i.e. an over-caring mother

Normal Investigation Diseases

Nervous 

• Functional Neurological Disorders

• Headache disorders

  • Tension headache, Migraine, Cluster Headache

  • Concussion

• Psychiatry illnesses

  • Schizophrenia, bipolar

  • Generalised anxiety disorder, obsessive compulsive disorder, depression, bulimia nervosa, PTSD

  • Addictions: alcohol, substance, gambling & Behavioural

  • Paediatrics: Autism Spectrum Disorder, ADHD

• Psychological conditions: 

  • Malingering, factious disorders, Munchausen & Munchausen by proxy, illness anxiety disorder, hypochondriasis

• Chronic Fatigue Syndrome, Insomnia, chronic pain

Senses: ENT & ophthalmology

• Globus

Endocrine

• Psychogenic primary polydipsia

Cardiovascular

• Anterior chest wall syndrome/ atypical chest pain

Respiratory

• Habit cough

Gastrointestinal

• GORD

• Irritable Bowel Syndrome

• Functional abdominal pain

Urinary system

• Overactive bladder (without detrusor overactivity

Female reproductive system

• Chronic pelvic pain

Musculoskeletal systems

• Fibromyalgia

• MSK back pain

Renal, female & male reproductive systems, hematopoietic & immune systems and skin: nil

Reflections

• Diseases of normal investigations predominantly affect the nervous system and have a connection to mental health

• They're predominantly a disorder of symptoms (syndromes) without clear pathogenesis

• Defining 'normal investigations' isn't straightforward- Alzheimer's typically has normal investigations clinically but would should abnormal histology on brain biopsy and IBS shows abnormalities in its gut flora; 

  • Psychiatric disorders could argue abnormalities on objective clinical questionnaires and one would expect to find abnormalities within the brain in schizophrenia if our investigations were precise enough

• The burden on healthcare of these conditions is large due to their high prevalence

Functional Neurological Disorders (FND)

Assessment

History

• Wide range of symptoms including non-epileptic attacks, limb weakness and chronic pain

Examination

• Hoover's sign: flexing the weak leg produces involuntary extension of healthy leg

Investigations

• Normal 

• Ruling out differentials: CT/MRI-H, nerve conduction studies, baseline bloods

Diagnosis

Diagnostic criteria: clinical

Management

Acute & long term

• Education

• Physiotherapy

• Symptomatic support (e.g. analgesia)

Resources and References

1. https://neurosymptoms.org/en/ 

Written in 2025