Ataxia and Cerebellar Disorders
Ataxia, which is an incoordination of movement, may affect gait, or it
may involve the limbs individually, together, or bilaterally, the lower
extremities only, or various combinations of the proceeding.
Disturbances of proprioception (sensory ataxia), vestibular input, and
weakness may also produce ataxia.
The cerebellum is concerned with regulating the timing, coordination, and
integration of movements, including extraocular movements and speech. It
functions closely with the motor cortex, basal ganglia, vestibular system and
spinal motor system.
Causes of Recurrent Falling Attacks without Apparent Loss of Consciousness
- Gait ataxia due to cerebellar, vestibular, or proprioceptive disorders
- Atonic seizures
- Cataplexy
- Basal ganglia disorders
- Parkinson’s disease
- Progressive supranuclear palsy
- Vertebrobasilar insufficiency
- Spinal cord compression at foramen magnum level (e.g., subluxation of
odontoid, basilar impression)
- Orthopedic disorders (e.g., patellar subluxation, arthritis of hip
joints).
- Normal pressure hydrocephalus
- Idiopathic falling attacks (especially affecting middle aged women)
Other Causes of Progressive or Chronic Ataxia
A type II Chiari or Arnold Chiari malformation includes distortion and
anomalous development of the cerebellum, but usually patients are seen because
of signs of hydrocephalus or spasticity, rather than because of ataxia. Midline
subarchnoid cysts may occur in the posterior fossa, usually in association with
a hydroplastic cerebellar vermis. The cysts may or may not be communicating with
the fourth ventricle. They may be asymptomatic, give rise to intermittent or
progressive symptoms of raised intracranial pressure due to hydrocephalus, or be
manifested by symptoms of gait ataxia, which may be intermittent.
Diagnosis is readily accomplished by CT or MRI scanning, and the
communications with the fourth ventricle can be ascertained by intrathecal
radionuclide injection and posterior fossa scanning.
A type II Chiari or Arnold Chiari malformation includes distortion and
anomalous development of the cerebellum, but usually patients are seen because
of signs of hydrocephalus or spasticity, rather than because of ataxia. Midline
subarchnoid cysts may occur in the posterior fossa, usually in association with
a hydroplastic cerebellar vermis. The cysts may or may not be communicating with
the fourth ventricle. They may be asymptomatic, give rise to intermittent or
progressive symptoms of raised intracranial pressure due to hydrocephalus, or be
manifested by symptoms of gait ataxia, which may be intermittent.