From the Guidelines
Tonic posturing in nocturnal frontal lobe epilepsy is characterized by sustained, asymmetric limb extension or contraction that typically occurs during sleep, involving abnormal stiffening of the body, often with one arm extended outward in a fencing-like position. This phenomenon is distinct from other forms of epilepsy and sleep disorders, and its characteristics can help differentiate it from conditions such as syncope, which may present with loss of consciousness and movements, but typically involves asynchronous and limited movements, rather than the forceful extension of extremities seen in tonic posturing 1. Some key features of tonic posturing in NFLE include:
- Sustained, asymmetric limb extension or contraction
- Abnormal stiffening of the body, often with one arm extended outward
- Vocalizations such as grunting or moaning
- Brief or no post-ictal confusion, allowing patients to quickly return to sleep
- Occurrence primarily during non-REM sleep
- Preservation of consciousness during many of these seizures The underlying cause of tonic posturing in NFLE is abnormal electrical discharges in the frontal lobe, particularly in the supplementary motor area or premotor cortex, which control voluntary movement planning and execution 1. Treatment for NFLE typically involves antiepileptic medications, which can help reduce the frequency and severity of tonic posturing episodes, and improve overall quality of life for patients with this condition.
From the Research
Description of Tonic Posturing in Nocturnal Frontal Lobe Epilepsy
- Tonic posturing in nocturnal frontal lobe epilepsy (NFLE) is characterized by sustained dystonic posturing, which is a type of complex motor behavior that occurs during sleep 2.
- This condition is also known as Sleep-Related Hypermotor Epilepsy (SHE), which is a focal epilepsy with seizures arising mainly during sleep and characterized by complex, often bizarre, motor behavior or sustained dystonic posturing 2.
- The seizures in NFLE can range from brief, stereotyped, sudden arousals to more complex dystonic-dyskinetic seizures and to prolonged "somnambulic" behavior, and can include tonic posturing 3.
- Tonic posturing is one of the seizure semiologies that can occur in NFLE, and it is often difficult to distinguish from other non-epileptic nocturnal paroxysmal events, such as parasomnias 2.
Clinical Characteristics
- NFLE affects both sexes, with a higher prevalence in men, and is frequently cryptogenetic with a strong familial trait for parasomnias and epilepsy 3.
- Seizures in NFLE can occur at any age, but tend to increase in frequency during life, and often appear more frequently between 14 and 20 years of age 3.
- Interictal and ictal scalp electroencephalography (EEG) are often normal, but the use of sphenoidal leads may be helpful in diagnosing NFLE 3.
- Videopolysomnography is mandatory to confirm the diagnosis of NFLE, and can help to distinguish it from other non-epileptic nocturnal paroxysmal events 3.
Treatment Options
- Carbamazepine is often effective at low doses for seizure control in NFLE, but a third of patients are resistant to anti-epileptic drugs (AED) treatment 3.
- Other treatment options for NFLE include oxcarbazepine, topiramate, and fenofibrate, which have been shown to be effective in reducing seizure frequency in some patients 4, 5, 6.