Pediatric emergency medicine trisk 103

ADEM is an immune-mediated demyelinating condition, generally
monophasic, which often occurs postinfectiously, predominantly in school-age
children. It is usually associated with focal neurologic deficits, often including
ataxia and various degrees of encephalopathy, but also cranial nerve
abnormalities, pyramidal signs, and speech impairment. Maximal severity is
usually observed within 2 to 5 days from onset of symptoms. MRI usually shows
reversible, ill-defined white matter lesions with frequent involvement of brain
(including cortical and subcortical structures such as thalami and basal ganglia)
and spinal cord. CSF often shows lymphocytic pleocytosis and increased protein.
Acute cerebellitis is defined as an acute cerebellar syndrome usually in the
context of a nonspecific recent infection, accompanied by altered mental status
and cerebellar edema on brain imaging.
TABLE 15.1
COMMON CAUSES OF ACUTE ATAXIA
Acute cerebellar ataxia
Drug ingestion
Guillain–Barré syndrome a
a Indicates

weakness or vertigo that may mimic ataxia.

Toxic ingestions (Table 15.3 ) are a common problem in the pediatric
population, and should always be considered among other medical etiologies. A
detailed history including available drugs in the child’s home, or the home of any
caregivers, can be critical in making this diagnosis. Benzodiazepines cause
lethargy, altered mental status, and ataxia. Antiepileptic drugs (AEDs),
particularly phenytoin and carbamazepine, are also causes of ataxia in the
pediatric population. Ingestions of these medications can often present with
nystagmus with ataxia. Dextromethorphan, a primary ingredient in many overthe-counter cough suppressants, is also an important drug to consider in an ataxic
patient. At lower doses, this can cause euphoria, which leads to its abuse,
particularly among adolescents; however, in higher doses it can cause ataxia.

Ethanol is a common substance of abuse among adolescents, but must also be
considered in younger children as ethanol is prevalent in many homes in the form
of beverages, cough syrups, and mouthwash and can lead to ataxia from
cerebellar dysfunction. Marijuana and synthetic cannabinoids are other common
substances of abuse that can lead to ataxia along with their myriad of symptoms,
and should be considered in a patient presenting with associated tachycardia or


mydriasis. Testing with urine drug screen, serum ethanol level, and antiepilepsy
drug levels, when applicable, should be considered in the workup for ataxia.


TABLE 15.2
DIFFERENTIAL DIAGNOSIS OF ACUTE OR RECURRENT ATAXIA,
INCLUDING LESS COMMON CAUSES
Infectious and immune mediated
Acute cerebellitis
Acute disseminated encephalomyelitis (ADEM)
Multiple sclerosis exacerbation
Tick paralysis a
Meningitis
Benign peripheral
Benign paroxysmal vertigo a
Labyrinthitis a
Cerebrovascular
Ischemic or hemorrhagic posterior circulation stroke
Cerebral sinovenous thrombosis
Vasculitis
Headache related
Migraine

Postconcussion syndrome
Conversion disorder
Genetic/metabolic diseases
Hartnup disease
Wilson disease
Maple syrup urine disease
Pyruvate decarboxylase deficiency
Episodic ataxia type 1 (paroxysmal ataxia and myokymia)
Episodic ataxia type 2 (acetazolamide-responsive ataxia)
Posterior fossa pathology
Acute hydrocephalus
Posterior fossa tumors
a Indicates

weakness or vertigo that may mimic ataxia.


TABLE 15.3
DRUGS AND TOXINS THAT MAY CAUSE ATAXIA
Benzodiazepines
Alcohol
Dextromethorphan
Marijuana and synthetic cannabinoids
Phenytoin
Carbamazepine
Tricyclic antidepressants
Antihistamines
Lead
5-Fluorouracil
Ethylene glycol

Primidone
Phenothiazines
Topiramate
Risperidone
Gabapentin
Phenobarbital
GBS is a postinfectious polyneuropathy with a peak incidence at ages 5 to 6
years that can cause ataxia, and must be considered in a patient presenting with
areflexia and weakness, particularly the classic presentation of ascending
paralysis and weakness. CSF analysis, particularly assessing for elevated protein
in the CSF, is key in diagnosing GBS. The clinician must also consider Miller
Fisher variant, which has more severe and more rapid onset than GBS, and
classically presents with ataxia, areflexia, and ophthalmoplegia. CSF pleocytosis
can also be seen with this illness; however, for definitive testing and diagnosis,
neurology consultation should be considered.
A rare but severe cause for acute ataxia is stroke , either hemorrhagic or
ischemic. Cerebellar bleeding in children can be associated with arteriovenous
malformations or cavernous hemangiomas and often presents with severe
headache and signs of increased intracranial pressure (ICP). Posterior circulation