Chapter R16–Z26 — Module 40
Alphabetical Overview of Neurological, Mental Health, Developmental & Physical Conditions
R — Conditions
Rasmussen’s Encephalitis
A rare, chronic inflammatory brain disease (usually in children) causing severe, drug-resistant seizures, progressive brain damage, and loss of motor/cognitive function.
Reactive Attachment Disorder (RAD)
A childhood condition caused by severe early neglect or abuse, leading to difficulty forming emotional bonds, emotional withdrawal, fear, and sadness.
Reading Disorder (Dyslexia / Specific Reading Disorder)
A learning difficulty affecting reading accuracy, fluency, and comprehension despite normal intelligence.
Reflex Sympathetic Dystrophy Syndrome (CRPS)
A chronic pain condition (often after injury) causing severe pain, swelling, and temperature/colour changes in a limb.
Refsum Disease
A rare genetic metabolic disorder where fatty acids build up in the body, leading to nerve damage, vision loss, and coordination issues.
Repetitive Motion Disorders
Conditions caused by repeated movement strain (e.g., tendonitis, carpal tunnel syndrome), leading to pain and reduced mobility.
Restless Legs Syndrome (RLS)
A neurological condition causing an uncontrollable urge to move the legs, especially at night, often disrupting sleep.
Rett Syndrome
A genetic neurodevelopmental disorder (mainly in girls) causing loss of speech, motor skills, and purposeful hand use after early development.
Reye’s Syndrome
A rare but serious condition causing brain swelling and liver damage, usually in children recovering from viral infections.
Rheumatoid Arthritis
An autoimmune disease where the immune system attacks joints, causing pain, inflammation, and long-term joint damage.
S — Conditions
Schizophrenia
A severe mental illness involving hallucinations, delusions, disorganised thinking, and impaired functioning.
Scoliosis
A physical condition involving abnormal sideways curvature of the spine.
Seizure Disorders (Epilepsy-related conditions)
Neurological conditions causing repeated seizures due to abnormal brain electrical activity.
Sensory Processing Disorder
A condition where the brain struggles to process sensory information (sound, touch, light, movement).
Specific Learning Disabilities
Includes dyslexia, dyscalculia, dysgraphia — affecting reading, writing, and maths skills.
Spina Bifida
A birth defect where the spinal column does not fully close, affecting movement and nerve function.
Spinal Cord Injury
Damage to the spinal cord causing partial or full loss of movement, sensation, and bodily control.
Stroke
A medical emergency where blood flow to the brain is blocked or reduced, causing brain damage.
T — Conditions
Tay-Sachs Disease
A rare genetic disorder causing progressive destruction of nerve cells, leading to severe disability and early death.
Tourette Syndrome
A neurological condition involving involuntary motor and vocal tics.
Traumatic Brain Injury (TBI)
Brain damage caused by external trauma (falls, accidents, impact injuries).
Tremors
Involuntary shaking movements caused by neurological dysfunction.
U — Conditions
Ulcerative Colitis
A chronic inflammatory bowel disease causing ulcers and inflammation in the colon.
Unipolar Depression (Major Depression)
A mood disorder causing persistent sadness, low motivation, and loss of interest.
Urofacial Syndrome
A rare genetic disorder affecting urinary function and facial expressions.
V — Conditions
Vertigo
A sensation of spinning or dizziness, often caused by inner ear disorders.
Visual Impairment / Blindness
Partial or complete loss of vision not correctable by glasses or lenses.
Vocal Cord Dysfunction
Abnormal movement of vocal cords causing breathing difficulty.
W — Conditions
Wheelchair Use (Mobility Disability Context)
Not a condition itself, but a mobility outcome linked to physical, neurological, or developmental disabilities.
Williams Syndrome
A genetic condition affecting heart health, development, and social personality traits.
X — Conditions
X-linked Spinal Muscular Atrophy (Kennedy’s Disease)
A rare inherited neurological disorder affecting motor neurons and muscle control.
Xeroderma Pigmentosum
A genetic condition causing extreme sensitivity to UV light and high risk of skin cancer.
Y — Conditions
Yaws
A chronic bacterial infection affecting skin, bones, and cartilage, potentially leading to disability if untreated.
Z — Concept
“Zebra” (Rare Disease Concept)
A medical term used to describe rare, complex, or hard-to-diagnose conditions. It represents the rare disease community.
Cross-Module Theme (Important Understanding)
Across all R–Z conditions, there are shared patterns:
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Neurological differences (brain, nerves, development)
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Physical disabilities and chronic illness
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Mental health conditions
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Learning and developmental differences
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Rare diseases that are often misdiagnosed
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Conditions requiring lifelong support or management
R–Z Mental Health, Neurological, Personality, Sleep, and Behavioural Disorders (Alphabet Module)
🧠 R Disorders
Reactive Attachment Disorder (RAD)
A childhood condition where children struggle to form healthy emotional bonds with caregivers, often due to neglect or early trauma.
Reading Disorder (Dyslexia)
A neurodevelopmental learning disorder affecting reading accuracy, fluency, spelling, and decoding.
Recurrent Brief Depression
Short but repeated episodes of depression that occur frequently but do not last long individually.
Relational Disorder
Difficult or dysfunctional interaction patterns between individuals that significantly affect relationships and functioning.
REM Sleep Behaviour Disorder
A sleep disorder where individuals physically act out dreams during REM sleep.
Restless Legs Syndrome (RLS)
A neurological condition causing uncomfortable sensations and an urge to move the legs, especially at rest.
Retrograde Amnesia
Memory loss for events that occurred before a brain injury or neurological event.
Rett Syndrome (Rett Disorder)
A neurodevelopmental disorder affecting motor and cognitive development, now often classified within autism spectrum-related conditions.
Rumination Syndrome
A condition where food is repeatedly regurgitated and re-chewed or re-swallowed without nausea or illness.
🧠 S Disorders
Schizoaffective Disorder
A condition combining symptoms of schizophrenia (hallucinations, delusions) with mood disorder symptoms (depression or mania).
Schizoid Personality Disorder
A personality disorder marked by emotional detachment and a strong preference for solitude.
Schizophrenia
A severe mental health disorder affecting perception of reality, often involving hallucinations, delusions, and disorganised thinking.
Schizophreniform Disorder
Similar to schizophrenia but shorter in duration (between 1–6 months).
Schizotypal Personality Disorder
Characterised by eccentric behaviour, unusual beliefs, and social anxiety.
Seasonal Affective Disorder (SAD)
A form of depression linked to seasonal changes, often worsening in winter months.
Sedative, Hypnotic, or Anxiolytic Use Disorder
Dependence on sedative drugs such as benzodiazepines or sleep medications.
Selective Mutism
An anxiety disorder where a person cannot speak in certain social settings despite being able to speak normally elsewhere.
Separation Anxiety Disorder
Excessive fear or distress when separated from attachment figures.
Sexual Disorders (Male & Female)
Conditions affecting sexual functioning, such as:
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Erectile disorder
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Low sexual desire disorders
Sexual Addiction (Hypersexuality)
Compulsive engagement in sexual thoughts or behaviours despite negative consequences.
Sexual Masochism Disorder
Sexual arousal from experiencing pain, humiliation, or suffering.
Sexual Sadism Disorder
Sexual arousal from causing pain or suffering to others.
Shared Psychotic Disorder
A rare condition where delusional beliefs are shared between two or more people.
Sleep Arousal Disorders
Includes parasomnias such as sleepwalking and sleep terrors.
Sleep Paralysis
Temporary inability to move or speak when falling asleep or waking up.
Sleep Terror Disorder
Episodes of intense fear during sleep, often with screaming or confusion.
Social Anxiety Disorder
Severe anxiety in social situations due to fear of judgment or embarrassment.
Somatization Disorder
Physical symptoms without a clear medical cause, linked to psychological distress.
Specific Phobias
Intense irrational fear of specific objects or situations (e.g., heights, spiders).
Stendhal Syndrome
A psychosomatic reaction to overwhelming art or beauty causing dizziness, confusion, or fainting.
Stereotypic Movement Disorder
Repetitive, non-functional movements such as rocking or hand-flapping.
Stimulant Use Disorder
Addiction to stimulant drugs such as cocaine or amphetamines.
Stuttering (Childhood-Onset Fluency Disorder)
Speech disorder involving disruptions in fluency, such as repetition or prolongation of sounds.
Substance-Related Disorders
A broad category covering addiction or misuse of alcohol, drugs, or toxins affecting the brain and behaviour.
🧠 T Disorders
Tardive Dyskinesia
Involuntary repetitive movements caused by long-term use of antipsychotic medication.
Tobacco Use Disorder
Dependence on nicotine products such as cigarettes or vaping.
Tourette Syndrome
Neurological disorder involving motor and vocal tics.
Transient Tic Disorder
Temporary tics lasting less than one year, common in childhood.
Transient Global Amnesia
Sudden, temporary memory loss without a clear cause.
Transvestic Disorder
Sexual arousal linked to cross-dressing in certain contexts.
Trichotillomania
Impulse control disorder involving compulsive hair-pulling.
🧠 U Disorders
Undifferentiated Somatoform Disorder
Physical symptoms that do not fully match a specific medical or psychological diagnosis but cause distress.
🧠 V Disorders
Vaginismus
Involuntary tightening of vaginal muscles making penetration painful or impossible.
Voyeuristic Disorder
Sexual arousal from watching others who are unaware they are being observed.
🧠 W–Z Section
There are no officially recognised standalone psychiatric disorders commonly classified under W, X, Y, or Z in major diagnostic manuals such as the DSM or ICD.
