Tag: alpha EEG

Periodic K-alpha sleep EEG activity and periodic limb movements during sleep: comparisons of clinical features and sleep parameters

Abstract:

The K-alpha sleep electroencephalographic (EEG) phenomenon is characterized by periodic (approximately 20-40 seconds) K-complexes, immediately followed by alpha-EEG activity (7.5-11 Hz) of 0.5- to 5.0-second duration. A group of 14 subjects with the periodic K-alpha anomaly was found to have a similar distribution pattern of interevent intervals as compared with previously published data for sleep-related periodic limb movements during sleep (PLMS). Sleep parameters and somatic symptoms of 30 patients with K-alpha were compared with 30 patients with PLMS. The periodic K-alpha group was predominantly female, younger, exhibiting more slow-wave sleep, gastrointestinal symptoms and muscular complaints and fewer movement arousals on overnight polysomnography. The K-alpha group presented uniformly with complaints of unrefreshing sleep, often associated with fibromyalgia and chronic fatigue syndrome. The PLMS group was predominantly male, showed greater sleep disruption and presented with a variety of sleep-related symptoms.

 

Source: MacFarlane JG, Shahal B, Mously C, Moldofsky H. Periodic K-alpha sleep EEG activity and periodic limb movements during sleep: comparisons of clinical features and sleep parameters. Sleep. 1996 Apr;19(3):200-4. http://www.ncbi.nlm.nih.gov/pubmed/8723376

 

Determination of observer-rated alpha activity during sleep

Abstract:

Patients suffering from chronic fatigue syndrome (CFS) have been described as having alpha intrusion into sleep. In a separate study of the relationship between depression and CFS, we investigated the sleep of CFS patients.

We could not detect any observable alpha anomaly in our group of CFS patients. It is possible that there is a subgroup of CFS patients in whom no alpha anomaly is present. However, the sleep electroencephalogram (EEG) montage used in our study was different to that employed by previous researchers.

This paper investigates the influence of electrode derivations on the outcome of observable alpha ratings. We compared simultaneous recordings of sleep EEG using three commonly employed montages.

Our results indicate that use of the mastoid reference (montage 1) results in the highest observer-related alpha. This may suggest that data regarding alpha intrusion should always be collected using montage 1.

However, there is a possibility that the mastoid electrode is not electrically silent and is contaminating the data of the referenced channels. The implications of these findings are discussed in relation to the validity of alpha intrusion measurement of CFS and fibromyalgia.

 

Source: Flanigan MJ, Morehouse RL, Shapiro CM. Determination of observer-rated alpha activity during sleep. Sleep. 1995 Oct;18(8):702-6. http://www.ncbi.nlm.nih.gov/pubmed/8560138

 

Sleep and symptoms in fibrositis syndrome after a febrile illness

Abstract:

Sleep physiology and symptoms of 9 patients with fibrositis syndrome secondary to a febrile illness were compared to 9 patients with fibrositis syndrome who did not attribute their symptoms to a febrile illness and to 10 healthy controls.

Both patient groups showed an alpha EEG (7.5 to 11 Hz) nonrapid eye movement sleep anomaly, had similar observed tender points, and self-ratings of musculoskeletal pain.

These findings suggest that patients with postfebrile fibrositis have a nonrestorative sleep disorder characteristic of patients with fibrositis syndrome and share similar symptoms with patients who have a “chronic fatigue syndrome.”

 

Source: Moldofsky H, Saskin P, Lue FA. Sleep and symptoms in fibrositis syndrome after a febrile illness. J Rheumatol. 1988 Nov;15(11):1701-4. http://www.ncbi.nlm.nih.gov/pubmed/3236304