Investigations of autonomic function include the table-tilt test or active stand to measure orthostatic blood pressure and sphincter electromyography. The latter detects denervation in the external urethral sphincter secondary to degeneration of Onuf’s nucleus in the spinal cord. Cardiac scintigraphy demonstrates reduced sympathetic MIBG uptake in the heart in PD but not MSA. Clinically, this test is more commonly used in Eastern countries than in the West. Video-polysomnography can be helpful in identifying the sleep disturbances associated with MSA (sleep apnoea, nocturnal stridor, REM sleep behaviour disorder (REMBD)).

Steele, Richardson and Olszewski presented the first clinicopathological descriptions of PSP in 1963 and 1965. Unsteadiness of gait, with falls within the first year, frequently backwards, represents the presenting feature in more than 60 % of cases. Bradykinesia and rigidity may be associated, often resulting in a misdiagnosis of PD, but these features have an axial predominance in PSP, unlike PD which tends to have asymmetric lateralised features in the early stages. In a minority of cases gaze difficulties, dysarthria, dysphagia or cognitive impairment may be the prominent early symptoms (see Fig. 10.4). The illness progresses to an immobile state over less than 10 years in the majority of cases. Recent years have witnessed a considerable expansion in the volume of clinic-pathological series describing PSP and there is now widespread recognition that there can be considerable phenotypic heterogeneity, particularly in the early years of the disease. This has given rise to the proposed clinical subdivision of PSP into a number of sub-entities, and there is some pathological data to corroborate this. Such clinical subtypes include the classic phenotype as described by Steele et al. (PSP-RS); PSP-parkinsonism (PSP-P) which can mimic IPD with asymmetric features, tremor and partial levodopa responsivity for a number of years, as well as a corticobasal syndrome (PSP-CBS), a primary progressive aphasia phenotype (PSP-PNFA), and rarely, gait initiation failure and freezing of gait, speech or writing in the absence of other parkinsonian signs (PSP-PAGF). Ultimately, however, the disease evolves in the vast majority of patients into the classical picture of axial rigidity, postural instability, oculomotor palsies, bulbar dysfunction and cognitive (particularly frontal lobe) impairment.

In contrast to the short and shuffling gait, stooped posture, narrow base, and flexed knees typically seen in PD, PSP patients tend to be erect with a stiff and broad-based gait, often with poor safety awareness and impulsivity (“motor recklessness”). They tend to pivot when turning, which further compromises balance. Although the PSP gait can appear ataxic, cerebellar signs are not a feature.

Oculomotor abnormalities are common in PSP. Symptomatic eye movement difficulty is typically present within 4 years after the onset. Prior to this, most patients have slowing of vertical saccades, saccadic pursuit, breakdown of opticokinetic nystagmus in the vertical plane, poor convergence and square-wave jerks (SWJs). The latter occurs in nearly all patients with PSP and rarely in PD. Vertical supranuclear ophthalmoparesis is a prominent feature of PSP. The patient loses range of vertical gaze, with downgaze usually worse than upgaze, and will describe difficulty walking down stairs. This voluntary gaze restriction is supranuclear; it therefore can be overcome by using the vestibulo-ocular reflex (“Doll’s eye” manoeuvre) achieved by passive flexion/extension of the neck. Involuntary orbicularis oculi contractions producing blepharospasm and ‘apraxia’ of eyelid opening and eyelid closure affect up to one third of PSP patients.