0071643192.pdf

ATA X IA

Ataxia is the failure to make smooth, intentional movements. Ataxia and gait
disturbances are symptoms of particular disease processes and not diagnoses in
and of themselves. In general, ataxia can be divided into two groups:

Motor (cerebellar) ataxia:

■ Disorders of cerebellum (most common)
■ Sensory receptors and afferent pathways intact, but integration of pro-
prioceptive information is poor
■ Usually ipsilateral to lesion
■ Far less commonly due to infarcts in the internal capsule, thalamic nucleus,
or frontal lobe

NEUROLOGY

TABLE 15.10. Pertinent Neurologic Findings in Coma

EXAM FINDING INTERPRETATION

Funduscopic examination Spontaneous venous pulsations Normal intracranial pressure

Pupillary constriction Absent response to light Midbrain structural lesion or topical cycloplegic

drug use.

Unequal pupils Structural lesion or normal variant.

Eye position Tonic deviation Seizure or irritant brain lesion

Corneal reflex (tests CN Absent Posterior fossa or brainstem lesions

V and VII)

Oculocephalic reflex (doll’s eye) Conjugate deviation of eyes in Intact brainstem

directionoppositeto passive

head rotation

Conjugate deviation in same No brainstem function

direction as head rotation

Oculovestibular reflex Irrigate ear canal with 10 mL cold

(cold caloric) water:

■Horizontal nystagmuswith fast Intact cortex and brainstem

componentawayfrom irrigated ear

■Tonic deviation to side of irrigation Toxic/metabolic or lesion above brainstem

No response No brainstem function

Response to painful stimuli Decorticate posturing (elbow/wrist Severe damage above the midbrain

flexion, shoulder adduction and

internal rotation, forearm supination)

Decerebrate posturing (elbow/wrist Damage at the midbrain or diencephalon

extension, shoulder adduction and

internal rotation, forearm pronation)

Asymmetric movement Structural lesions