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Transient neurologic syndromes: A diagnostic approach

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Release date: February 1, 2018
Expiration date: January 31, 2019
Estimated time of completion: 1 hour

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ABSTRACT

Clinicians are often confronted with patients who have transient neurologic symptoms lasting seconds to hours. In many of these patients, their symptoms have gone away or returned to baseline by the time of evaluation, making the diagnosis even more challenging. Elements such as correlation of symptoms with vascular territory, prodromes, triggers, motor symptoms, confusion, and sleep behavior can guide the diagnostic workup.

KEY POINTS

  • Transient ischemic attack, migraine aura, and partial seizures are common and often can be differentiated by their distinctive symptoms.
  • Episodes of confusion in a patient with diabetes raise the possibility of hypoglycemic encephalopathy; other possibilities include hyperventilation syndrome and transient global amnesia.
  • Daytime sleepiness in a young patient may be due to narcolepsy or parasomnias.


 

References

Many patients present to their primary care physicians, urgent care centers, and emergency rooms because of neurologic symptoms lasting seconds to hours. Their problems can be a cause for concern and a challenge to diagnose, as in many cases their symptoms have returned to baseline by the time of evaluation. Referral to a neurologist may not be practical for all of them, particularly given that a consultation may take a long time to obtain.

Understanding the causes of transient neurologic syndromes and their phenomenology may help the clinician diagnose, triage, and treat such conditions effectively.

Here, we outline several transient neurologic syndromes—transient ischemic attack (TIA), migraine with aura, partial seizures, hypoglycemic encephalopathy, hyperventilation syndrome, transient global amnesia, narcolepsy, parasomnias, and some rarer conditions— focusing on their diagnostic elements. Others, such as drug-induced transient neurologic syndromes, vertigo, and dizziness, have been well discussed elsewhere. 1–3

THE BIG 3: TIA, MIGRAINE, SEIZURES

A 45-year-old woman with a history of tobacco use and headaches presents to the emergency department with a 4-month history of episodic numbness and tingling of her right arm and face. She reports a prodromal state of anxiety and irritability 24 to 48 hours before symptom onset.

The sensory symptoms begin on her face and gradually progress down the arm and eventually to her fingers. They fully resolve within 2 hours without sequelae. Family members have noted some “slurred speech” during the episodes, and the episodes are occasionally preceded by a unilateral, throbbing headache that improves with rest.

What are the possible causes of her symptoms?

Transient ischemic attack

If a patient reports transient neurologic symptoms and has vascular risk factors, TIA is often the default diagnostic consideration. The risk of stroke is 9.9% in the 2 days after a TIA, 13.4% at 30 days, and 17.3% at 90 days. 4 Rapid recognition offers a crucial period to minimize the possibility of permanent impairment. Interventions include modifying risk factors (hypertension, diabetes, and smoking) and starting an antiplatelet drug, an anticoagulant drug, or both, and possibly a statin.

It can be difficult to determine if this workup needs to be completed in the inpatient or outpatient setting. There is no clear consensus, but the ultimate goal is timely evaluation (within 24 to 48 hours). The ABCD2 ( Age, Blood pressure, Clinical features, Duration of symptoms, and Diabetes) risk factor calculator was developed to help triage patients, though it has limitations. 5,6

One should assess a patient’s history of a possible TIA in a stepwise fashion. First, analyze the patient’s age and demographics for known vascular risk factors or central embolic sources (eg, atrial fibrillation). Then consider the symptoms. TIA symptoms have rapid onset, usually within seconds 7; symptoms with a more gradual crescendo suggest a nonvascular cause. 8 TIA manifestations should resolve within 1 hour, and most studies suggest symptom resolution within 10 minutes is specific for a TIA. 9–11 TIA symptoms are negative neurologic phenomena that denote a loss of function, such as loss of vision, motor weakness, or sensory numbness.

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