Epilepsy See Also Chapter

Epilepsy is the chronic condition of recurrent unprovoked seizures, and can be caused by multiple etiologies that result in dysfunction of cortical neurons. SRBDs are common in individuals with epilepsy. Polysomnographic investigations by Malow (27) showed that nearly one-third of patients with medically refractory epilepsy had a respiratory disturbance index of greater than five. Although the exact cause of this increased prevalence of OSA in this population is unknown, we have speculated that this may be in part related to the underlying CNS dysfunction similar to that seen in other neurological disorders such as stroke (28). Therapeutic intervention for epilepsy also may increase the risk of sleep apnea. Valproate, viga-batrin, and gabapentin are well known to promote weight gain thus increase the likelihood for sleep apnea (29-31).

Additionally, benzodiazepines and barbiturates may cause suppression in responsiveness to carbon dioxide and oxygen desaturation and increase upper airway musculature relaxation (30). Another form of therapy for epilepsy, vagus nerve stimulation, has been reported to potentially increase airway disturbance during sleep in some patients (31). This therapy may increase airway resistance from stimulation of the recurrent laryngeal nerve or by interfering with the respiratory sensory feedback. Seizures themselves can cause respiratory disturbance and apnea (Figs. 1 and 2). It is important for clinicians to differentiate the underlying etiology of the apnea for subsequent treatment.

OSA may also increase the recurrence of seizures. Mechanisms for the apparent increase in seizures may be two-fold. OSA may increase seizures based upon sleep fragmentation, or by the repetitive oxygen desaturation (32). Both of these mechanisms may lower the seizure threshold and may be active in patients with OSA. Several studies have shown that for some patients regardless of age, treatment

FIGURE 1 Focal onset seizure and obstructive sleep apnea. Polysomnographie epoch of a patient with history of epilepsy showing the onset of a focal seizure (arrow) with bi-frontal spread obscured by muscle activity then bilateral spike and wave activity. Following the onset of the seizure an ensuing obstructive apnea (*) is followed by a central respiratory pause (#). Abbreviations: A2, right auricular (reference) electrode; C3, left central electrode; EKG, electrocardiogram; IC-EMG, intercostal electromyogram; LAT, left anterior tibialis electromyogram; LOC, left outer canthi; LUE, left upper electro-oculogram; Mvt, movement; O1, left occipital electrode; O2 Sat, oxygen saturation; P nasal, nasal pressure; RAT, right anterior tibialis electromyogram; ROC, right outer canthi; RUE, right upper electro-oculogram; Submtl EMG, submental electromyogram; Therm, thermocouple; Tachycar or Tach, tachycardia.

FIGURE 1 Focal onset seizure and obstructive sleep apnea. Polysomnographie epoch of a patient with history of epilepsy showing the onset of a focal seizure (arrow) with bi-frontal spread obscured by muscle activity then bilateral spike and wave activity. Following the onset of the seizure an ensuing obstructive apnea (*) is followed by a central respiratory pause (#). Abbreviations: A2, right auricular (reference) electrode; C3, left central electrode; EKG, electrocardiogram; IC-EMG, intercostal electromyogram; LAT, left anterior tibialis electromyogram; LOC, left outer canthi; LUE, left upper electro-oculogram; Mvt, movement; O1, left occipital electrode; O2 Sat, oxygen saturation; P nasal, nasal pressure; RAT, right anterior tibialis electromyogram; ROC, right outer canthi; RUE, right upper electro-oculogram; Submtl EMG, submental electromyogram; Therm, thermocouple; Tachycar or Tach, tachycardia.

FIGURE 2 Focal onset seizure and central sleep apnea. Polysomnography epoch of a patient showing the focal onset of seizure activity (arrow) with associated central apneas. Abbreviations: A2, right auricular (reference) electrode; C3, left central electrode; EKG, electrocardiogram; LOC, left outer canthi; Mvt, movement; O2 Sat, oxygen saturation; ROC, right outer canthi; Submtl EMG, submental electromyogram; Therm, thermocouple.

FIGURE 2 Focal onset seizure and central sleep apnea. Polysomnography epoch of a patient showing the focal onset of seizure activity (arrow) with associated central apneas. Abbreviations: A2, right auricular (reference) electrode; C3, left central electrode; EKG, electrocardiogram; LOC, left outer canthi; Mvt, movement; O2 Sat, oxygen saturation; ROC, right outer canthi; Submtl EMG, submental electromyogram; Therm, thermocouple.

of the OSA resulted in reduction of seizures in patients with focal onset seizures and generalized seizures (33-35).

Polysomnographic investigation of these patients does require additional precautions. The testing environment should be made safe for patients who may incur seizures during the testing procedure. These patients should be observed throughout the testing period and video recording should be time linked to the polysomnogram. Some patients may have events that cause them to fall out of bed. Therefore, the bed should not be near sharp edges and padding the bed rails may be helpful. Technologists should be familiar with recognizing the various types of seizures and the appropriate first aid. Physicians should also instruct the technologists on the appropriate emergency steps for prolonged seizures, status epilepticus, and airway management. Interpreting physicians should also consider expanding the number of electroencephalographic channels recorded. These channels should focus on the frontal and temporal regions, and the interpreting physician should review the electroencephalographic component with a 10-second per page window to aid in the identification of more subtle electroencephalographic features (36).

Treatment of sleep apnea in patients with epilepsy is similar to treatment of sleep apnea in the general population. Several case series have shown that treatment of OSA may improve seizure frequency (31-33). Our experience is that patients accept CPAP well. We have not had any significant patients become entangled in the tubing or injured with the device during a seizure. Patients who have postictal vomiting should not be considered candidates for oral appliances nor full-face masks because of the high potential risk of aspiration. Other investigators have promoted the use of respiratory stimulant medications such as protriptyline or acetazolamide (32,37).

Sleep Apnea

Sleep Apnea

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