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 normal investigations whilst clinically fitting criteria

• 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 

• Medically unexplained symptoms: symptoms that are not attributable to a formal diagnosis 

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 (FND)

• 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

• Urinary frequency (without detrusor overactivity)

• Chronic UTI

Female reproductive system

• Chronic pelvic pain

Musculoskeletal systems

• Fibromyalgia

• MSK back pain

Dermatology

• Dermatitis artefacta, delibrate self harm

Male reproductive systems, hematopoietic & immune systems: nil

Diseases of 'Normal' Investigations vs Functional Pathology

• Some of these diseases have abnormal structural issues that haven't yet been identified by modern investigations (e.g. Schizophrenia), therefore arguably all of these conditions would have abnormal investigations if the investigations were advanced enough

  • E.g. Schizophrenia has likely abnormal fMRIs and IBS may have abnormal gut flora

• Functional disorders generally should be positive diagnoses based on clinical criteria- i.e. IBS or FND, therefore

  • All functional disorders have 'normal' investigations however

  • Not all symptoms with 'normal' investigations are functional disorders

• Stress is prevalent here and a key differential is excessive sympathetic drive with insufficient parasympathetic recovery

• 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)

Professor Stone has an excellent website on functional neurological disorders: https://neurosymptoms.org/en/ 

Stress and Disease

Diseases cause stress

• Diseases, by definition, cause a problem to the body; usually causing distress

• Particularly chronic diseases are heavily linked with concomitant functional disorders

Stress causes disease

• Stress- acute or chronic is common and presents with the effects of sympathetic overactivation and lack of parasympathetic recovery

• Acute and chronic Stress (sympathetic nervous system and HPAA- cortisol) response produceds a range of symptoms:

Anxiety and stress related changes to the body

Excess of sympathetic nervous system and lack of parasympathetic nervous system

Nervous

• Anxiety, low mood, repetitive (OCD) or restrictive behaviours (anorexia)

• Headache, irritability, poor sleep, mild confusion

Endocrine

• Tiredness

Cardiovascular

• Palpitations, episodes of shortness of breath

Respiratory

• Episodes of hyperventilation

• Dry oral mucosa -> cough

Gastrointestinal

• Constipation 

• Nausea, vomiting, 

• Disordered eating: anorexia (loss of appetite) and/ or binge eating

Urinary

• Urinary frequency

Reproductive

• Dysregulated periods

Musculoskeletal

• Painful joints (arthralgia), painful muscles (myalgia)

Haemopoietic 

• Increased infections

Skin

• Dry skin, self damaging skin without cause

Diseases caused by Stress

The difficulty with writing lists is that there is a spectrum of strength of causality, some of these conditions are linked to high stress

Nervous: 

• Alzheimer's disease, insomina, pseudo-dementia

• Anxiety: generalised anxiety disorder, panic disorder, OCD, depression,

• Suicide

• Addictions- drug, alcohol, behavioural

Senses

• Dry eye

Endocrine

• T2DM / Metabolic Syndrome

Cardiovascular

• Hypertension

Gastrointestinal

• IBS

Urinary

• Detrusor overactivity

Female Reproductive

• Amenorrhoea

Dermatology

• Dermatitis artefacta

Behaviors associated with social stress

• Self neglect and reduced basic functions

  • Nutrition and water intake

  • Sanitation to pass urine and faeces

  • Safe housing for sleep

• Detrimental behaviours

  • Smoking

  • Drugs and alcohol

  • Poor nutrition, lack of exercise (metabolic syndrome)

Sources of Stress

• Relationships

  • Bereavement

  • Relationship breakdown: divorce

  • Abusive: physical, verbal and sexual abuse

• Work related

• Poverty and financial stress

• Homelessness, incarceration and eviction

Resources and References

1. https://neurosymptoms.org/en/ 

Written in 2025