Synopsis
Differentiate PSP's early axial, gaze and fall syndrome from CBS's asymmetric cortical-motor disorder, understand diagnostic uncertainty and prioritise swallowing, communication, mobility and anticipatory support.
- Progressive supranuclear palsy is suggested by early unexplained backward falls, axial rigidity, slowing of vertical saccades and later supranuclear vertical gaze palsy, especially downgaze impairment.
- The vestibulo-ocular reflex can initially overcome a supranuclear gaze limitation with a doll's-head manoeuvre, distinguishing it from ocular motor-nerve or muscle restriction when safely examined.
- PSP commonly adds frontal executive change, apathy or impulsivity, dysarthria, dysphagia, photophobia, blepharospasm and a surprised facial appearance.
- Corticobasal syndrome usually begins with markedly asymmetric limb dysfunction combining rigidity, dystonia, myoclonus or bradykinesia with apraxia, cortical sensory loss, alien-limb phenomena or language impairment.
- PSP and CBS are clinical syndromes, not guaranteed pathology: PSP syndrome is often a tauopathy, while CBS can result from corticobasal degeneration, Alzheimer pathology, PSP or another process.
- Levodopa response is generally limited, but an adequate monitored trial can identify useful symptomatic benefit and should not be judged after one small test dose.
- MRI helps exclude stroke, tumour and hydrocephalus and may show midbrain atrophy in PSP or asymmetric cortical atrophy in CBS; supportive patterns are not standalone diagnoses.
- Falls, eye-movement limitations, apraxia and impaired insight create distinctive hazards that require occupational, physiotherapy, orthoptic and home assessment early.
- Speech and swallowing impairment can progress before patients volunteer difficulty; repeated speech-and-language assessment and anticipatory nutrition discussions are essential.
- No medicine reliably stops progression, so honest prognosis, communication support, carer assessment, palliative input and advance-care planning belong alongside active symptom management.
Key red flags
Abrupt asymmetry, sudden language loss, fever, acute confusion or a step-change in swallowing suggests stroke, infection, seizure or medication harm rather than expected neurodegenerative progression.
Investigation priorities
Identify saccadic slowing, supranuclear gaze limitation, axial postural instability or the asymmetric cortical-motor combination.
Management branches
Axial parkinsonism is accompanied by early backward falls, visual scanning difficulty or frontal change.
- Map the date of first fall, freezing, speech, swallowing and cognitive change and directly examine vertical saccade velocity, gaze range, vestibulo-ocular response, axial tone and pull response.
- Arrange specialist MRI and movement-disorder assessment, screen injury and bone health and trial levodopa adequately when potential symptomatic benefit justifies it.
- Refer early to physiotherapy, occupational therapy, orthoptics and speech and language therapy for weighted walking advice, environmental modification, visual strategies, communication and swallow planning.
- Review driving and high-risk activities promptly because impaired downgaze and sudden falls can threaten safety before limb weakness is severe.
Key medicines
Levodopa combination therapyUse an adequate specialist-supervised trial titrated to gait, rigidity and meaningful daily activities.Monitor postural hypotension, hallucinations, nausea and dyskinesia; taper if ineffective rather than stopping suddenly, and do not let a partial response erase cortical or gaze signs.
Botulinum toxin type AAn expert injector selects muscles and dose at intervals usually around twelve weeks by product.Local weakness can worsen head control or swallowing, products are not dose-equivalent and injection goals and response should be documented each cycle.