7.5  Spino-Cerebellar Ataxia


7.5.1  Spino-Cerebellar Ataxia (SCA 3) with normal vestibular-ocular reflex. (150 SSC)

Age at test:       41

Key Signs:        

The two cases of SCA shown below indicate how balance and gait tests may be used to screen fore early systems of SCA with and without central vestibular problems. Two legged stance is normal in this patient, but as soon as the patient is required to perform tasks with stance on one leg, especially tandem gait, excessive roll angle values are observed (see first set of traces below), and the time takes to complete such tasks is longer. Note that pitch and roll trunk control are equally unstable. For the task of walking over barriers, roll is very unstable (see second set of traces). The patient could not perform the task of walking up and down stairs without assistance, thus the Index in the Summary is only available without stairs.




Walking 8 tandem steps



Walking over low barriers spaced 1 m apart.



Indicates that patient cannot control trunk roll sway well when required. Thus roll velocities are much greater than pitch for tandem walking and roll angle sway is generally abnormal. Stance tasks are performed within normal bounds.



7.5.2  Spino-Cerebellar Ataxia (SCA7) with low vestibular-ocular reflex gain (146 SSC)

Age a test:        44

Key signs:

In addition to poor roll control described for the patient above, this patient shows additional abnormalities due to a central vestibular deficit, for example, abnormal sway standing eyes closed with tremor at 6-7 Hz (see below) and inability to stand on one leg eyes open. Walking with voluntary head pitching or head rotation is abnormal (see summary below)


Standing on two legs, eyes closed



The sensory analysis of stance indicates that the patient is using visual and somato-sensory inputs to control stance to a high degree, but is unable to use vestibular inputs and therefore has a low value for this sensory input in the sensory analysis. The patient’s roll control for tandem walking is borderline normal. However the control of pitch velocity is abnormal across several gait tasks. For the barriers task roll angle sway is abnormal.