Pediatric emergency medicine trisk 0407 0407

CHAPTER 15 ■ ACUTE ATAXIA
JACLYN N. KLINE, LUCA BARTOLINI

INTRODUCTION
Ataxia is defined as impaired coordination of voluntary movements, usually
caused in children by cerebellar dysfunction or, less frequently, vestibular or
proprioceptive afferent dysfunction. While uncommon, acute ataxia in children is
important to recognize, because an early diagnosis may have significant
therapeutic implications. Ataxia is usually associated with other signs of
neurologic dysfunction, and the three most common causes of acute ataxia in
children are: (1) Acute postinfectious cerebellar ataxia, (2) Drug ingestion, and
(3) Guillain–Barré syndrome (GBS) and its variants (Table 15.1 ).

HOW TO DIAGNOSE ATAXIA ON NEUROLOGIC
EXAMINATION
Ataxia can manifest as abnormal timing of contraction of agonist/antagonist
muscles (dysrhythmia) and abnormal movement trajectory, resulting in frequent
overshooting and overcorrecting (dysmetria).
Symptoms and signs often relate to the anatomic location of the cerebellum
that is affected by the underlying process. Gait and truncal ataxia are observed in
diffuse processes and those involving the cerebellar vermis. Gait ataxia is the
most common presentation and consists of a wide-based gait with inability to
walk without support, especially on tandem gait. When the deficit is more evident
with the eyes closed, sensory or vestibular causes should be considered. Young
children may just refuse to ambulate.
Lesions in the cerebellar hemispheres or peduncles are associated with
ipsilateral limb ataxia. Appendicular ataxia, caused by lesions in the lateral
hemispheres of the cerebellum that leads to ataxic movements in the extremities,
can be unmasked by performing the rapid alternating movement, finger tapping,
and finger-to-nose tests, especially if the examiner’s finger is held at the extreme
of the patient’s reach and moved unpredictably. Similarly, heel-to-shin test can be

done for the lower extremities, but generally requires more cooperation and is
rarely feasible in younger patients. Overshoot can also be observed when the
patient is asked to suddenly raise his outstretched arms from their lap to the level
of the examiner’s hand. This also allows detection of postural tremor, which is
also a cerebellar sign. Examination can be affected by the presence of upper or