Multiple system atrophy

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

MSA involves alpha-synuclein accumulation mainly within oligodendroglia, producing degeneration across basal ganglia, cerebellar, brainstem and autonomic networks. The result is not one fixed phenotype but a moving combination of bradykinesia and rigidity, gait or limb ataxia, neurogenic blood-pressure failure, urinary and sexual dysfunction, speech and swallowing impairment and abnormal breathing. Symptoms most often begin after age fifty, and a very young onset should widen genetic, metabolic and other differentials.

Autonomic chronology is diagnostically important. Erectile dysfunction can precede motor features; urinary urgency may progress to incomplete emptying and retention; orthostatic hypotension causes light-headedness, visual dimming, coat-hanger neck pain, cognitive clouding or syncope. Neurogenic pressure failure is more likely when the pulse response is inappropriately small, but medicines, dehydration, cardiac disease and endocrine causes still need exclusion. Supine hypertension may coexist, making aggressive pressure raising hazardous.

There is no cure or established disease-modifying treatment. An expert movement-disorder diagnosis uses current clinical criteria, longitudinal evolution and supportive testing. Therapy seeks safer standing and walking, reliable bladder emptying, protected swallowing and breathing, understandable communication and maintained participation. Decisions often involve trade-offs: more pressor effect versus nocturnal hypertension, less urgency versus retention, reduced drooling versus thick secretions, or more tone reduction versus weaker transfers.

Key points

Multiple system atrophy is a progressive synucleinopathy combining autonomic failure with parkinsonism, cerebellar dysfunction or both; MSA-P and MSA-C describe the predominant motor pattern.
Early urinary urgency, incontinence or retention, erectile dysfunction and neurogenic orthostatic hypotension are major clues when they are disproportionate to motor disability.
Parkinsonism is commonly symmetrical or axial and responds poorly or only transiently to levodopa, although a supervised adequate trial remains worthwhile in many patients.
Cerebellar gait and limb ataxia, dysarthria or oculomotor signs can dominate, especially in MSA-C, and are not expected features of uncomplicated Parkinson disease.
Inspiratory stridor, nocturnal noisy breathing, sleep-disordered breathing and disproportionate antecollis are high-value warning signs that require specialist airway assessment.
Pyramidal signs, cold discoloured hands or feet, emotional incontinence, REM sleep behaviour disorder and rapid progression can support the syndrome but are not individually diagnostic.
MRI may show putaminal or pontocerebellar atrophy and a hot-cross-bun appearance; these are supportive findings and can be absent early or occur in other disease.
Management is symptomatic: salt and fluid strategies where safe, compression, postural training, bladder emptying plans, levodopa trial, speech and swallowing care and falls prevention.
Pressor therapy can worsen supine hypertension, and bladder antimuscarinics can worsen retention, cognition and postural symptoms; physiology and post-void residual guide treatment.
Progression is usually faster than Parkinson disease, so early driving, work, communication, nutrition, carer, palliative and advance-care conversations are appropriate alongside active symptom treatment.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Sporadic alpha-synucleinopathy

MSA is usually a sporadic neurodegenerative disorder with abnormal alpha-synuclein accumulation in glial cells and no single established environmental cause.

Unknown initiating cause

No single environmental or inherited cause is established. A strong family history should instead prompt assessment for genetic ataxia, parkinsonism or autonomic neuropathy.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Glial alpha-synuclein accumulation
Misfolded alpha-synuclein forms oligodendroglial inclusions, disrupting support for axons and promoting neuroinflammation and degeneration over time.
2
Autonomic network degeneration
Loss within central autonomic pathways impairs blood-pressure, bladder, sexual, sweating and respiratory control as disease advances.
3
Motor-system degeneration
Striatonigral injury causes poorly responsive parkinsonism, while olivopontocerebellar loss produces gait, limb, speech and eye-movement ataxia.
4
Progressive multisystem failure
Combined autonomic, motor, bulbar and airway dysfunction advances more rapidly than typical Parkinson disease and limits compensatory reserve.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Autonomic-first syndrome

Years or months of erectile dysfunction, urinary urgency, incomplete emptying or orthostatic presyncope precede symmetrical bradykinesia, rigidity or cerebellar gait impairment.

Neurogenic orthostatic hypotensionRed flag

Standing produces light-headedness, dim vision, weakness, neck or shoulder ache and sometimes syncope, with a substantial pressure fall and an insufficient compensatory pulse rise after confounders are addressed.

MSA-P phenotype

Bradykinesia, rigidity and postural instability are often axial or relatively symmetrical, progression is faster and sustained functional levodopa response is less than expected for Parkinson disease.

MSA-C phenotype

Progressive broad-based gait, limb dysmetria, scanning or slurred speech and cerebellar eye-movement abnormalities accompany autonomic failure, without another acquired or genetic ataxia explanation.

Airway and sleep cluesRed flag

Harsh inspiratory noise, nocturnal stridor, choking, abnormal sighing, obstructive or central sleep-disordered breathing and morning headache signal laryngeal or respiratory involvement.

Competing diagnoses

Parkinson disease, PSP, dementia with Lewy bodies, pure autonomic failure, diabetic or amyloid neuropathy, structural cord disease and genetic or immune ataxias can overlap and require targeted review.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Lying and serial standing blood pressure with pulseFirst step
Why
Document orthostatic physiology, symptom correlation and competing medicine or volume effects.
Interpretation and limitations
Measure after adequate supine rest and through at least three minutes standing, extending when delayed hypotension is suspected. A blunted heart-rate response supports neurogenic failure but is altered by beta blockade and rhythm disease.
02
Bladder scan and urological assessment
Why
Identify residual urine, retention, infection and upper-tract risk before treating frequency or incontinence.
Interpretation and limitations
A substantial post-void residual supports autonomic dysfunction and changes drug choice. Urinalysis, renal profile, ultrasound and urodynamics are added according to symptoms and specialist advice.
03
MRI brain
Why
Exclude structural, vascular and inflammatory causes and seek supportive putaminal, pontine or cerebellar patterns.
Interpretation and limitations
Putaminal change, pontocerebellar atrophy and a hot-cross-bun sign may support MSA but lack perfect sensitivity and specificity. A normal early scan does not exclude clinical disease.
04
Levodopa trial and objective motor assessment
Why
Find the subgroup with worthwhile symptomatic response and distinguish true non-response from inadequate exposure.
Interpretation and limitations
Record target gait, rigidity and activities before and after a tolerated specialist trial. Partial response does not rule out MSA; absent response matters only when dose, duration and absorption were adequate.
05
Sleep, laryngeal and respiratory evaluation
Why
Investigate stridor, apnoea, nocturnal desaturation, dysphonia and impaired airway protection.
Interpretation and limitations
ENT laryngoscopy, respiratory review and polysomnography may be required. Differentiate laryngeal stridor from ordinary snoring because intervention and risk differ.
06
Autonomic and mimic testing
Why
Characterise multisystem autonomic failure and exclude neuropathic, endocrine, cardiac, drug and ataxia alternatives.
Interpretation and limitations
An autonomic laboratory may use tilt, beat-to-beat pressure, sweat and cardiovascular reflex tests. Bloods, ECG, neuropathy studies, genetics or immune tests follow the phenotype rather than a universal panel.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Parkinson disease

Asymmetric onset and sustained levodopa response favour Parkinson disease; early severe autonomic failure, stridor and cerebellar signs favour MSA.

Progressive supranuclear palsy

Early backward falls, axial rigidity and vertical gaze slowing point towards PSP rather than autonomic-cerebellar MSA.

Dementia with Lewy bodies

Early dementia, visual hallucinations and marked cognitive fluctuation support DLB; prominent early cognitive decline is less typical of MSA.

Autonomic neuropathy or genetic ataxia

Length-dependent sensory loss, amyloid features or a family pedigree supports peripheral or inherited disease rather than sporadic central degeneration.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Diagnostic suspicionJoin autonomic and motor chronologyFirst stepProgressive parkinsonism or ataxia occurs with prominent urinary, sexual or blood-pressure dysfunction.

1Build a dated timeline of erectile, bladder, bowel, sweating, blood-pressure, sleep, speech, swallowing and motor symptoms and reconcile medicines that could reproduce them.
2Examine standing physiology, eye movements, parkinsonism, cerebellar and pyramidal signs and gait; measure post-void residual and obtain MRI to exclude alternatives and seek supportive features.
3Refer to a movement-disorder specialist for criteria-based longitudinal diagnosis, an adequate levodopa trial and targeted autonomic, urological or genetic investigation.

02Orthostatic symptomsImprove upright function safelyNeurogenic hypotension causes presyncope, cognitive clouding, falls or syncope.

1Remove aggravating medicines where possible and address dehydration, anaemia, infection, deconditioning and large meals; teach slow staged standing and physical counter-pressure manoeuvres.
2Individualise fluid and salt intake after checking heart and kidney status, consider abdominal compression and raise the bed head to reduce nocturnal pressure and morning volume loss.
3If disability persists, specialist-prescribe midodrine or another locally supported agent, then monitor standing benefit and supine hypertension rather than chasing a single seated target.
4EscalationEscalate recurrent injurious syncope, chest symptoms or atypical pulse behaviour for cardiac as well as autonomic assessment.

03Bladder dysfunctionProtect emptying before continenceUrgency, incontinence, hesitancy, recurrent infection or a raised post-void residual is present.

1Measure residual volume, urinalysis and renal function and review constipation, pelvic pathology and medicines rather than assuming all urinary symptoms are neurogenic.
2Use timed voiding and continence input, and teach clean intermittent catheterisation when incomplete emptying is clinically important and the patient or carer can manage it.
3Only add urgency medicines after weighing retention, cognition, constipation and postural pressure; involve neurourology for recurrent infection, upper-tract concern or difficult catheter planning.

04Airway and progressionAnticipate bulbar and respiratory riskStridor, nocturnal breathing change, dysphagia, weight loss or recurrent chest infection emerges.

1Arrange urgent speech-and-language swallowing assessment and ENT, respiratory or sleep investigation for stridor, with critical evaluation when breathing is compromised.
2Adapt food texture, communication, secretion and respiratory support based on instrumental assessment and individual risk, not a blanket restriction.
3Discuss gastrostomy, non-invasive support, tracheostomy implications, emergency plans and advance care early enough for informed choice while continuing symptom-directed treatment.

Key medicines and prescribing safety5 treatments · regimens, roles and cautions

A minority obtain useful improvement in bradykinesia or rigidity even though the average response is limited or transient.

Levodopa combination therapy

Undertake an adequately dosed specialist trial, titrated to recorded functional targets and individual tolerance.

May worsen orthostatic hypotension, hallucination and dyskinesia; do not withdraw abruptly, and judge benefit against gait, transfers and daily activities rather than examination alone.

Peripheral alpha-agonism can improve disabling neurogenic orthostatic hypotension after physical measures are insufficient.

Midodrine

A common start is 2.5 mg three times daily while upright, titrated under specialist guidance.

Avoid doses near bedtime and monitor supine hypertension, urinary retention, scalp itching and piloerection; heart, kidney and vascular contraindications require review.

Expands intravascular volume for selected hypotensive patients when non-drug measures and alternatives are considered.

Fludrocortisone

Specialists may begin 50 to 100 micrograms once daily and titrate cautiously by response.

Check supine pressure, oedema, weight, potassium, renal and heart failure; long-term steroid effects and limited evidence make regular benefit review essential.

Provides reliable emptying and protects against overdistension when neurogenic retention is significant.

Intermittent catheterisation

Frequency is individualised from bladder volumes, intake, dexterity and the neurourology continence plan.

Training, hand function, carer capacity, urethral trauma and symptomatic infection matter; long-term indwelling alternatives carry different burdens.

May reduce frequency and urge incontinence when bladder storage symptoms remain troublesome despite behavioural measures.

Urgency treatment

Choose a formulary antimuscarinic or beta-3 agonist only after measuring residual urine and blood pressure.

Antimuscarinics may worsen retention, constipation and cognition; mirabegron can raise pressure and has interactions. Recheck symptoms and residual volume.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Syncope and pressure instability

Neurogenic orthostatic hypotension causes falls and cerebral hypoperfusion, while supine hypertension complicates fluid and pressor treatment.

Stridor and respiratory failure

Laryngeal dysfunction and sleep-disordered breathing can cause nocturnal obstruction, sudden deterioration and difficult airway management during progression.

Falls, dysphagia and aspiration

Parkinsonism, ataxia and bulbar weakness produce fractures, malnutrition, communication loss and recurrent aspiration pneumonia in advanced disease.

Urinary retention and infection

Poor bladder emptying requires catheter strategies and can cause recurrent infection, stones, renal risk and major loss of independence.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record supine and standing blood pressure, pulse and symptoms after non-drug or pressor changes, including evening readings when nocturnal hypertension is possible.
Follow post-void residual, catheter volumes, renal function, infection symptoms and upper-tract risk; urinary frequency alone does not show whether emptying is safe.
Ask about stridor, witnessed apnoea, choking, weak cough, morning headache and daytime sleepiness at every review and escalate new airway noise promptly.
Track gait, falls, levodopa response, ataxia, speech, swallowing, weight, hydration and communication needs with therapy and dietetic input.
Review constipation, sexual health, mood, sleep, cognition, carer strain, equipment, housing, work and DVLA responsibilities as part of multisystem care.
Reconsider the diagnosis if progression, imaging, autonomic testing or medication response develops a pattern inconsistent with MSA.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Residual volume precedes tablets

Urgency can coexist with incomplete emptying, so prescribing an antimuscarinic without a bladder scan may convert hidden retention into a complication.

Supine pressure is the trade-off

A medicine that improves standing may create dangerous nocturnal hypertension; success is better function without unacceptable recumbent pressure.

Stridor is not snoring

A high-pitched inspiratory sound can reflect laryngeal dysfunction and deserves urgent specialist assessment rather than routine sleep-hygiene advice.

Levodopa response is graded

Some MSA patients gain useful benefit, so neither a trial nor a partial response should be used as a simplistic binary diagnostic test.

MRI signs support

The hot-cross-bun sign and putaminal abnormalities increase confidence in the right phenotype but are neither required nor exclusive to MSA.

Early planning is active care

Communication aids, swallowing choices and emergency airway preferences are most valuable when discussed before cognitive, speech or respiratory deterioration constrains choice.

11Common pitfallsFrequent interpretation and management errors.

01
Calling early urinary symptoms benign overactive bladder without measuring residual urine or considering a progressive motor syndrome.
02
Treating orthostatic hypotension from a seated blood pressure alone and never checking supine hypertension.
03
Dismissing MSA because levodopa gives partial improvement or MRI lacks a hot-cross-bun sign.
04
Using antimuscarinic treatment despite significant retention, constipation or cognitive burden without follow-up.
05
Recording nocturnal stridor as ordinary snoring and delaying airway, respiratory and sleep assessment.
06
Waiting for advanced dysphagia before discussing communication, nutrition, aspiration and future-care preferences.