Ocular motor abnormalities of Steele Richardson

 05 November 2004

EARLY TO LATE

Normal ocular movements even in advanced disease

Impaired down gaze

Loss of fast component of optokinetic nystagmus

Loss of caloric induced nystagmus

Deterioration in pursuit movements/saccades

Square wave jerks

Also seen physiological (darkness), MSA, PP, Alzheimer’s, Huntington’s, cerebellar disease

            Dependent upon definition of amp & frequency

            Normals 2.3/min vs PSP(in 85%) >10/min

Cogwheel pursuit movements

            Degeneration of pontine nuclei

Hypometric saccades

            Dependent on range from central fixation ie >20⁰ in 77% normals

More prominent in PSP compared to other Parkinsonian syndromes

Loss of Bell’s phenomenon

Complete loss of vertical then horizontal

            Degeneration of mesencephalic premotor structures

            Vertical gaze palsy can also be lost in DLB, CBGD, MSA, CJD & Whipples

            But pattern of loss will imply PSP

Loss of convergence ability

Clinical features differentiating PSP from related disorders (CART analysis)

PSP vs PD:      unstable gait, absence of tremor dominant disease, poor Dopa response

PSP vs DLB:    supranuclear vertical gaze palsy, gait instability, absence of delusions

PSP vs MSA:   supranuclear vertical gaze palsy,  increased age at symptom onset

PSP vs CBGD: gait abnormality, severe upward gaze palsy, absence of alien limb

PSP vs Pick’s:  postural instability