Depressive symptoms account for differences between self-reported versus polysomnographic assessment of sleep quality in women with myofascial TMD.

Patients with temporomandibular disorder (TMD) report poor sleep quality on the Pittsburgh Sleep Quality Index (PSQI). However, polysomnographic (PSG) studies show meagre evidence of sleep disturbance on standard physiological measures. The present aim was to analyse self-reported sleep quality in TMD as a function of myofascial pain, PSG parameters and depressive symptomatology. PSQI scores from 124 women with myofascial TMD and 46 matched controls were hierarchically regressed onto TMD presence, ratings of pain intensity and pain-related disability, in-laboratory PSG variables and depressive symptoms (Symptoms Checklist-90). Relative to controls, TMD cases had higher PSQI scores, representing poorer subjective sleep and more depressive symptoms (both P < 0·001). Higher PSQI scores were strongly predicted by more depressive symptoms (P < 0·001, R2 = 26%). Of 19 PSG variables, two had modest contributions to higher PSQI scores: longer rapid eye movement latency in TMD cases (P = 0·01, R2 = 3%) and more awakenings in all participants (P = 0·03, R2 = 2%). After accounting for these factors, TMD presence and pain ratings were not significantly related to PSQI scores. These results show that reported poor sleep quality in TMD is better explained by depressive symptoms than by PSG-assessed sleep disturbances or myofascial pain. As TMD cases lacked typical PSG features of clinical depression, the results suggest a negative cognitive bias in TMD and caution against interpreting self-report sleep measures as accurate indicators of PSG sleep disturbance. Future investigations should take account of depressive symptomatology when interpreting reports of poor sleep.

Validity of self-reported sleep bruxism among myofascial temporomandibular disorder patients and controls.

Sleep bruxism (SB), primarily involving rhythmic grinding of the teeth during sleep, has been advanced as a causal or maintenance factor for a variety of oro-facial problems, including temporomandibular disorders (TMD). As laboratory polysomnographic (PSG) assessment is extremely expensive and time-consuming, most research testing this belief has relied on patient self-report of SB. The current case-control study examined the accuracy of those self-reports relative to laboratory-based PSG assessment of SB in a large sample of women suffering from chronic myofascial TMD (n = 124) and a demographically matched control group without TMD (n = 46). A clinical research coordinator administered a structured questionnaire to assess self-reported SB. Participants then spent two consecutive nights in a sleep laboratory. Audiovisual and electromyographic data from the second night were scored to assess whether participants met criteria for the presence of 2 or more (2+) rhythmic masticatory muscle activity episodes accompanied by grinding sounds, moderate SB, or severe SB, using previously validated research scoring standards. Contingency tables were constructed to assess positive and negative predictive values, sensitivity and specificity, and 95% confidence intervals surrounding the point estimates. Results showed that self-report significantly predicted 2+ grinding sounds during sleep for TMD cases. However, self-reported SB failed to significantly predict the presence or absence of either moderate or severe SB as assessed by PSG, for both cases and controls. These data show that self-report of tooth grinding awareness is highly unlikely to be a valid indicator of true SB. Studies relying on self-report to assess SB must be viewed with extreme caution.

Masticatory muscle sleep background electromyographic activity is elevated in myofascial temporomandibular disorder patients.

Despite theoretical speculation and strong clinical belief, recent research using laboratory polysomnographic (PSG) recording has provided new evidence that frequency of sleep bruxism (SB) masseter muscle events, including grinding or clenching of the teeth during sleep, is not increased for women with chronic myofascial temporomandibular disorder (TMD). The current case-control study compares a large sample of women suffering from chronic myofascial TMD (n = 124) with a demographically matched control group without TMD (n = 46) on sleep background electromyography (EMG) during a laboratory PSG study. Background EMG activity was measured as EMG root mean square (RMS) from the right masseter muscle after lights out. Sleep background EMG activity was defined as EMG RMS remaining after activity attributable to SB, other orofacial activity, other oromotor activity and movement artefacts were removed. Results indicated that median background EMG during these non-SB event periods was significantly higher (P < 0·01) for women with myofascial TMD (median = 3·31 µV and mean = 4·98 µV) than for control women (median = 2·83 µV and mean = 3·88 µV) with median activity in 72% of cases exceeding control activity. Moreover, for TMD cases, background EMG was positively associated and SB event-related EMG was negatively associated with pain intensity ratings (0-10 numerical scale) on post-sleep waking. These data provide the foundation for a new focus on small, but persistent, elevations in sleep EMG activity over the course of the night as a mechanism of pain induction or maintenance.

Classification of sleep-disordered breathing.

Increasing recognition of sleep-disordered breathing (SDB) and its morbidity have prompted reevaluation of techniques to identify respiratory events during sleep. The present study was designed to evaluate the utility of various metrics of SDB and to identify the optimal respiratory metric that objectively correlates to symptoms of excessive daytime somnolence (EDS). Metrics were derived from combinations of conventional apnea/hypopnea, flow limitation events (transient elevated upper airway resistance identified by characteristic flattening on the flow/time tracing, using a noninvasive nasal cannula technique), desaturation, and arousal. A total of 137 subjects underwent clinical evaluation and nocturnal polysomnogram. In 34 randomly selected subjects, the best metrics for discriminating between 13 subjects with no EDS/snoring and 21 patients with EDS and snoring were identified by receiver operator curve analysis. Of the metrics and cut points tested, a total respiratory disturbance index (RDI(Total), sum of apneas, hypopnea, and flow limitation events) of 18 events/h was found to have the best discriminant ability (100% sensitivity and 96% specificity). Prospective testing of this metric was then performed with the remaining 103 subjects (14 nonsnoring non-EDS, 21 snoring non-EDS, 68 snoring with EDS). Using this cutoff of 18 events/h, we obtained 71% sensitivity and 60% specificity for identifying subjects with EDS. We conclude that, in subjects with upper airway dysfunction, an index that incorporates all respiratory events provides the best quantitative physiological correlate to EDS.

Non-Invasive detection of respiratory effort-related arousals (REras) by a nasal cannula/pressure transducer system.

STUDY OBJECTIVES: The published AASM guidelines approve use of a nasal cannula/pressure transducer to detect apneas/hypopneas, but require esophageal manometry for Respiratory Effort-Related Arousals (RERAs). However, esophageal manometry may be poorly tolerated by many subjects. We have shown that the shape of the inspiratory flow signal from a nasal cannula identifies flow limitation and elevated upper-airway resistance. This study tests the hypothesis that detection of flow limitation events using the nasal cannula provides a non-invasive means to identify RERAs. DESIGN: N/A. SETTING: N/A. PATIENTS: 10 UARS/OSAS and 5 normal subjects INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: All subjects underwent full NPSG. Two scorers identified events from the nasal cannula signal as apneas, hypopneas, and flow limitation events. Two additional scorers identified events from esophageal manometry. Arousals were scored in a separate pass. Interscorer reliability and intersignal agreement were assessed both without and with regard to arousal. The total number of respiratory events identified by the two scorers of the nasal cannula was similar with an Intraclass Correlation (ICC) =0.96, and was essentially identical to the agreement for the two scorers of esophageal manometry (ICC=0.96). There was good agreement between the number of events detected by the two techniques with a slight bias towards the nasal cannula (4.5 events/hr). There was no statistically significant difference (bias 0.9/hr, 95%CI -0.3-2.0) between the number of nasal cannula flow limitation events terminated by arousal and manometry events terminated by arousal (RERAs). CONCLUSION: The nasal cannula/pressure transducer provides a non-invasive reproducible detector of all events in sleep disordered breathing; in particular, it detects the same events as esophageal manometry (RERAs).

Nonconvulsive status epilepticus in theophylline toxicity.

CASE REPORT: A 53-year-old cocaine user was on chronic therapy with theophylline, albuterol, and ipratropium for asthma and nifedipine for hypertension. Acute asthma treatment that increased the serum theophylline to 35 micrograms/mL was associated with tonic clonic seizures followed by bizarre, lateralized posturing. Electroencephalogram seizure activity lasting 10 days was consistent with nonconvulsive status epilepticus, Complex Partial, type II. Theophylline was considered the probable instigator of this underdiagnosed neurologic disorder.