No, this edition of Briefs was not an excuse to use a tongue twister as the title. It is however viral season. An viruses can cause (through some undetermined mechanism) a condition called acute cerebellar ataxia which generally occurs in children less than 5 years of age. It manifests in a wobble (or per the parents “drunk”) gait. Dysmetria, nystagmus and dysarthria may also occur, but are more rare. If the diagnosis is suspected on history and exam, and the child’s mental status is normal they can either be discharged home, or admitted to an inpatient service if the child’s gait is significantly abnormal as to risk injury.
Let’s circle back to ataxia in general shall we? It is important to remember that ataxia is a disorder of intentional movement. That is, it only manifests itself when the patient decides to move/do something. You can see it effect the trunk and/or extremities. Many parts of the nervous system can be involved include the peripheral nerves, spinal cord, cerebellum or cerebrum. Systemic/metabolic disorders and drug intoxication – notably phenytoin and ethanol – can cause it as well. You exam can help you focus on the potential location of the defect in the following ways.
If it is the cerebellum…
You will see nystagmus, staggering, and a wide-based gait
If it is the spinal cord…
You will see ataxic symptoms when the patient stands with their eyes closed (Romberg’s sign)
If possible you should also get the patient to perform hell to shin, rapid alternating hand movements – like when you play patty-cake with a toddler (an abnormal test her indicates dysdiadochokinesis – which is fun to spell), heel to to walking, and tandem gait. You’ll also certainly want to find out the length of symptoms. ACUTE ataxia has an onset of <24 hours. Drug toxicity (anticonvulsants, alcohol & sedative-hypnotics), acute metabolic processes (hypoglycemia), and CNS infections. The aforementioned acute cerebellar ataxia fits into this bucket. It is generally self-limited and improves within a few days. If you have an infant with chaotic, rapid conjugate eye movements (opsoclonus) you should worry about neuroblastoma.
Chronic intermittent ataxia‘s most common cause is a basilar migraine. If you are the first provider to see this patient you still need to rule out acute infection, ingestion or mass lesion. This means that you should strongly consider labs (including LP) and imaging as warranted.
Chronic progressive ataxia can be debilitating, and often progresses over weeks to months in an insidious fashion. Causes include brain tumors, hydrocephalus and neurodegenerative disorders. Ataxia, headache and irritability in a child under 6 years of age is classic for the diagnosis of a medulloblastoma. When the cerebral ventricles swell in hydrocephalus the frontopontocerebellar fibers are stretched. They do not like to be stretched, and respond by causing headache, vomiting and ataxia. If you suspect any of these call your favorite neurosurgeon and/or oncologist as the situation warrants.
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