A Neurological Cause of Recurrent Choking During Sleep

Abstract

We describe a case of nocturnal choking episodes caused by insular seizures. Recurrent choking spells from sleep showed no response to treatment for sleep apnea or gastroesophageal reflux. Laryngoscopy revealed no abnormalities. Although continuous EEG monitoring during events was normal, ictal SPECT imaging showed increased radiotracer uptake in the left insular region, an area involved in sensation of the upper gastrointestinal tract. The episodes remitted after initiation of an antiepileptic drug. Obstructive sleep apnea is the most common cause for presentation to a sleep center, but seizures should remain in the differential diagnosis of nocturnal choking episodes.

Citation:

Davis KA; Cantor C; Maus D; Herman ST. A neurological cause of recurrent choking during sleep. J Clin Sleep Med 2008;4(6):586–587.

A 34-year-old man was referred to the neurology service from the sleep center for further evaluation of recurrent stereotyped episodes of choking for four years beginning in 2002. Initially, these episodes occurred only at night, lasting 15 to 45 seconds, causing the patient to awaken with a sense of anxiety and on occasion to jump out of bed. The patient was initially diagnosed with obstructive sleep apnea (OSA) at an outside hospital after polysomnogram demonstrated an apnea-hypopnea index of 6 events per hour. Treatment of OSA with weight loss, CPAP, and upper airway surgery produced no improvement in symptoms. Esophageal pH monitoring was normal and treatment for gastroesophageal reflux was unsuccessful. Laryngoscopy showed no vocal cord abnormalities.

The patient's choking spells increased in frequency from once per month to 4 to 5 per night in 2006. In addition, he had 4 nocturnal episodes in 2006 suggestive of generalized seizures, with witnessed generalized shaking and postictal confusion. A prolactin level drawn after an episode with loss of consciousness was more than 100. Six months prior to presentation, the patient began having daytime episodes of a choking sensation lasting 10 to 15 seconds, without alteration of consciousness. Prior to referral to our center, EEG and 72-hour ambulatory EEG were normal. Head CT was unremarkable. MRI was not performed because of metal in the patient's cheek.

The patient was admitted to the Epilepsy Monitoring Unit for continuous video-EEG monitoring for further classification of these events. Several typical events were recorded, but ictal EEG showed no abnormalities. Ictal single photon emission computed tomography (SPECT) showed increased radiotracer uptake in the left insular region (Figure 1), consistent with simple partial insular seizures. After treatment with the antiepileptic drug oxcarbazepine, daytime episodes remitted, and nocturnal episodes markedly improved in frequency and severity.

Figure 1.

Ictal SPECT showed increased uptake in the left insular region (see arrows).

DISCUSSION

Given the prevalence of sleep disordered breathing and current referral patterns, the majority of patients presenting to a sleep center for evaluation of nocturnal dyspnea will have obstructive sleep apnea. In addition to apnea, however, the differential diagnosis of nocturnal choking episodes includes nocturnal panic attacks, laryngospasm, gastroesophageal reflux, and seizure. In the current case, focal seizures appeared to arise from the left insular region, with occasional secondary generalization. Insular seizures presenting with symptoms of upper airway obstruction have previously been described.¹

Confirming a diagnosis of insular seizures can be difficult, especially if only simple partial (no loss of awareness) seizures occur. Interictal EEG may not be diagnostic; spike frequency can be very low or even absent in extratemporal epilepsies. Because of the deep location of the insula, ictal scalp EEG is usually also unrevealing; only 20% to 30% of simple partial seizures show an ictal correlate on surface EEG.² Prolactin levels may be elevated following complex partial or secondarily generalized seizures, but can also be high after syncope.³ As in this case, focal increases in perfusion can sometimes be seen on ictal SPECT, but regions of hyperperfusion may be large and preclude exact seizure localization.⁴

The insula is believed to have multiple functions subserving movement, sensation, emotion and memory, including a patterned involvement in general and special visceral sensation of the gastrointestinal tract from the tongue extending at least to the esophagus.⁵ Electrical stimulation of the insular cortex in epilepsy patients undergoing stereotactic depth electrode recordings can evoke pharyngeal or laryngeal sensations of constriction ranging from breathing discomfort to a sensation of strangulation.⁶ Insular seizures often show early clinical symptoms of unpleasant sensations in the throat of variable intensity, followed by facial paresthesias, loss of awareness, and oroalimentary automatisms as seizures spread to mesial temporal regions.⁶

This case demonstrates that insular seizures can present with choking episodes which may be erroneously attributed to obstructive sleep apnea or reflux. When such episodes are stereotyped and do not resolve with CPAP or treatment for reflux, consideration should be given to the possibility of focal seizures even in the absence of EEG abnormalities.

DISCLOSURE STATEMENT

This was not an industry supported study. The authors have indicated no financial conflicts of interest.