Disorders• 8 SECTIONMotor Ocular Brainstem
Omnidirectional Slow Saccades
Key Facts
•Very slow refixational eye movements in both eyes in all directions
•In alert patients, usually caused by damage to saccadic generator in the pons
•Common causes:
• multiple sclerosis • pontine infarction • spinocerebellar ataxias (especially type 2) • progressive supranuclear palsy • genetic extraocular myopathies
Clinical Findings
•Very slow saccadic eye movements in both eyes in all directions
•In neurodegenerative conditions, may also find:
•saccadic intrusions • nystagmus • skew deviation • esotropia • cognitive decline • parkinsonism • spasticity • dysautonomia
Ancillary Testing
•MRI shows brainstem atrophy in some neurodegenerative states, orbital signs in orbitopathies, but is normal in genetic extraocular myopathies
•Blood for genetic testing of inherited ataxias
•Muscle biopsies for mitochondrial myopathies
•Serum for phenytoin level
•PCR for Whipple antigen
Differential Diagnosis
• Common causes:
•multiple sclerosis • pontine infarction • spinocerebellar ataxias (especially type 2) • progressive supranuclear palsy • genetic extraocular myopathies
•Uncommon causes:
•Friedreich ataxia • Huntington disease • phenytoin toxicity • Whipple disease
• paraneoplastic syndromes • ocular motor cranial nerve palsies • Fisher syndrome • myasthenia gravis • multiple system atrophies • Graves disease
• orbital myositis • orbital trauma
•Also consider sedative medication, psychogenic lack of cooperation
Treatment
• Depends on underlying condition
Prognosis
• Depends on underlying condition
150
Fig. 8.19 Omnidirectional slow saccades. When the patient attempts refi xational movements, the eyes move very slowly (indicated by dotted lines).
Saccades Slow Omnidirectional
Fig. 8.20 Hereditary cerebellar degeneration. Axial FLAIR
MRI shows severe atrophy of the cerebellar folia (arrow).
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Disorders• 8 SECTIONMotor Ocular Brainstem
Omnidirectional Saccadic Pursuit
Key Facts
•As the eyes follow a moving target, their movement is fragmented by fast catchup movements
•Found in very elderly, inattentive, tired, sedated, and sleepy patients
•Otherwise a sensitive but non-specific sign of brain dysfunction
•Prominent finding in cerebellar disorders
Clinical Findings
•Small jerky eye movements (saccades) replace smooth tracking movements (pursuit) when the patient is asked to follow a target moving at <40º/s in any direction
Ancillary Testing
• MRI often negative in degenerative, toxic, metabolic, or inattentive states
Differential Diagnosis
•Toxic, metabolic, or degenerative encephalopathy
•Poor attention
Treatment
• Depends on underlying condition
Prognosis
• Depends on underlying condition
152
Fig. 8.21 Omnidirectional saccadic pursuit. When the eyes follow a moving target, they fall behind and must catch up by using saccades (indicated by dashed lines).
Pursuit Saccadic Omnidirectional
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Section 9
Cerebral Gaze Disorders
Congenital Ocular Motor Apraxia |
156 |
Acquired Ocular Motor Apraxia (Supranuclear Gaze Palsy) |
158 |
Acute Horizontal Gaze Deviation |
160 |
Spasm of the Near Reflex |
162 |
Ping Pong Gaze |
164 |