Christian W. Hess

Early prognosis in coma after cardiac arrest: a prospective clinical, electrophysiological, and biochemical study of 60 patients.

BACKGROUND: The univariate study of clinical, electrophysiological, or biochemical variables has been shown to predict the outcome in postanoxic coma in about 50% of patients for each type of variable. Previous studies did not, however, consider the prognostic accuracy of a multivariate approach. METHODS: Sixty patients in coma for more than six hours after cardiac arrest were prospectively examined by means of repeated clinical examinations (including Glasgow coma score (GCS)), EEG, and medianus nerve somatosensory evoked potentials (SEPs). In 16 patients, the early concentrations of serum neuron specific enolase and ionised calcium were also measured. RESULTS: Within the first year after cardiac arrest, 20% of patients made a good neurological recovery; 80% remained in a vegetative state or died. Clinical examination correctly predicted outcome in 58% of patients, SEP in 59%, and EEG in 41%. The combination of clinical examination, SEP, and EEG raised the percentage of correct predictions to 82%, without false pessimistic predictions. Concentrations of serum neuron specific enolase and ionised calcium were of no additional prognostic help. Multivariate regression analysis identified the association of GCS < 8 at 48 hours with abnormal or absent early cortical SEPs as highly predictive of a bad outcome (risk = 97%, 95% confidence interval = 86-99%). CONCLUSION: The combination of GCS at 48 hours, SEP, and if these are non-conclusive, EEG, permits a more reliable prediction of outcome in postanoxic coma than clinical examination alone.

High prevalence of glaucoma in patients with sleep apnea syndrome.

OBJECTIVE To determine the prevalence of glaucoma in sleep apnea syndrome (SAS), an entity characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of cardiovascular and neurologic sequelae. DESIGN Cross-sectional study. PARTICIPANTS A total of 114 white patients consecutively referred for polysomnographic evaluation of suspected SAS. INTERVENTION Complete ophthalmologic examination, including computerized perimetry and simultaneous stereoscopic optic disc photographs. MAIN OUTCOME MEASURES Spearman rank correlations between the respiratory disturbance index during night sleep (RDI), a value used to diagnose and grade SAS, and visual acuity, intraocular pressure (IOP), visual field indices, presence or absence of glaucomatous optic disc changes, and diagnosis of glaucoma. Each correlation was controlled for age and body mass index. To compare proportions of patients harboring glaucoma, the binomial test was used. RESULTS Sixty-nine (60.5%) of the 114 patients had an RDI > or =10, which indicates SAS. Three patients had primary open-angle glaucoma, and two had normal-tension glaucoma. All patients with glaucoma had SAS. The observed prevalence of glaucoma in patients with SAS (5 of 69, 7.2%) was significantly higher than expected in a white population (2%) (P = 0.01). The RDI correlated positively with IOP (P = 0.025), visual field loss variance (P = 0.03), glaucomatous optic disc changes (P = 0.001), and diagnosis of glaucoma (P = 0.01). CONCLUSIONS Patients with SAS constitute a high-risk population for glaucoma and should therefore be screened for glaucoma.

Restless Legs Syndrome: A Clinical Study of 55 Patients

Background: Restless legs syndrome (RLS) is a common sleep disorder. In 1995, clinical criteria for the diagnosis of RLS were defined. Objective: To describe the clinical spectrum in a series of unselected RLS patients meeting the new diagnostic criteria. Methods: We prospectively assessed by questionnaire and clinical assessment the characteristics of 55 consecutive RLS patients (35 women, 20 men; mean age = 62 ± 16 years). Results: In 27% of the patients, RLS started before the age of 20 years (early-onset RLS). Sensory disturbances were painful in 56% of patients and felt in legs (98%), arms (35%), and ‘internally’ (45%). Motor disturbances included ‘dyskinesias while awake’ (36%). Insomnia (58%) was commoner than hypersomnia (24%). In 67% of the patients, no etiology of RLS was found (idiopathic RLS). Early-onset RLS was more commonly familial (p = 0.01) and associated with ‘growing pains’ (p = 0.005) than late-onset RLS. Patients with RLS and hypersomnia were younger (p = 0.01) and less commonly had painful sensations (p = 0.04) than patients with RLS and insomnia. Patients with idiopathic RLS were younger (p = 0.004), and less commonly had insomnia (p = 0.01) than patients with symptomatic RLS. Conclusions: RLS is a clinically pleomorphic syndrome, reflecting the contribution of multiple genetic and acquired factors in the pathogenesis of RLS.

Different Ipsilateral Representations for Distal and Proximal Movements in the Sensorimotor Cortex: Activation and Deactivation Patterns

Each hemisphere is known to be also involved in controlling the ipsilateral arm, but with an asymmetry favoring the dominant hemisphere. However, the relative role of primary and secondary motor areas in ipsilateral control is not well defined. We used whole brain functional magnetic resonance imaging in healthy human subjects to differentiate between contributions from primary and secondary areas during discrete unilateral distal finger and proximal shoulder movements. It was found that ipsilateral distal movements activated secondary areas only, while sparing or even significantly deactivating the primary sensorimotor cortex. Ipsilateral proximal movements substantially activated both SM1 and secondary areas. A newly defined small territory within the precentral gyrus, extending from the premotor cortex and intruding toward SM1, showed an activation pattern corresponding to secondary motor areas. Finally, the effects of hemispheric dominance were confirmed, but attributed exclusively to secondary areas. These new imaging findings agree well with functional requirements as well as established anatomical and neurophysiological data.

One Session of Repeated Parietal Theta Burst Stimulation Trains Induces Long-Lasting Improvement of Visual Neglect

Background and Purpose— Visual neglect is a frequent disability in stroke and adversely affects mobility, discharge destination, and length of hospital stay. It is assumed that its severity is enhanced by a released interhemispheric inhibition from the unaffected toward the affected hemisphere. Continuous theta burst transcranial magnetic stimulation (TBS) is a new inhibitory brain stimulation protocol which has the potential to induce behavioral effects outlasting stimulation. We aimed to test whether parietal TBS over the unaffected hemisphere can induce a long-lasting improvement of visual neglect by reducing the interhemispheric inhibition. Methods— Eleven patients with left-sided visual neglect attributable to right hemispheric stroke were tested in a visual perception task. To evaluate the specificity of the TBS effect, 3 conditions were tested: 2 TBS trains over the left contralesional posterior parietal cortex, 2 trains of sham stimulation over the contralesional posterior parietal cortex, and a control condition without any intervention. To evaluate the lifetime of repeated trains of TBS in 1 session, 4 trains were applied over the contralesional posterior parietal cortex. Results— Two TBS trains significantly increased the number of perceived left visual targets for up to 8 hours as compared to baseline. No significant improvement was found with sham stimulation or in the control condition without any intervention. The application of 4 TBS trains significantly increased the number of perceived left targets up to 32 hours. Conclusions— The new approach of repeating TBS at the same day may be promising for therapy of neglect.

Repetitive transcranial magnetic stimulation: a putative add-on treatment for major depression in elderly patients

Repetitive transcranial magnetic stimulation (rTMS) is a recent putative treatment for affective disorders. Several studies have demonstrated antidepressant effects of rTMS in younger patients; we aimed to assess its effect in older outpatients with treatment-resistant major depression. Twenty-four outpatients (mean age=62 years, S.D.=12) with major depression were randomized for sham or real stimulation and received 10 daily rTMS sessions (20 Hz, 2-s trains, 28-s intertrain intervals, 100% of motor threshold) in addition to the antidepressant medication. For sham stimulation, the coil was tilted 90 degrees. Depression severity was assessed using the Hamilton Depression Rating Scale, the Beck Depression Inventory, items from the NIMH self-rated symptom scale, and a visual analog depression scale. Mini-Mental Status Examination performance, memory, and executive and attentional functions were measured to control for cognitive side effects. Depression ratings revealed significant antidepressant effects within 2 weeks in both sham and real stimulation groups; however, there were no between-group differences. Treatment with rTMS was safe; adverse events were rare and not more prevalent in either group, and cognitive assessment did not show any deterioration. We were unable to demonstrate any additional antidepressant effects of real stimulation in elderly patients with treatment-resistant major depression. Therapeutic effects of rTMS in this clinically challenging patient group remain to be demonstrated.

Repetitive TMS over the human oculomotor cortex: Comparison of 1-Hz and theta burst stimulation

The aim of the study was to compare the effect duration of two different protocols of repetitive transcranial magnetic stimulation (rTMS) on saccade triggering. In four experiments, two regions (right frontal eye field (FEF) and vertex) were stimulated using a 1-Hz and a theta burst protocol (three 30Hz pulses repeated at intervals of 100ms). The same number of TMS pulses (600 pulses) was applied with stimulation strength of 80% of the resting motor threshold for hand muscles. Following stimulation the subjects repeatedly performed an oculomotor task using a modified overlap paradigm, and saccade latencies were measured over a period of 60min. The results show that both 1-Hz and theta burst stimulation had inhibitory effects on saccade triggering when applied over the FEF, but not over the vertex. One-hertz rTMS significantly increased saccade latencies over a period of about 8min. After theta burst rTMS, this effect lasted up to 30min. Furthermore, the decay of rTMS effects was protocol-specific: After 1-Hz stimulation, saccade latencies returned to a baseline level much faster than after theta burst stimulation. We speculate that these time course differences represent distinct physiological mechanisms of how TMS interacts with brain function.

Normal-tension glaucoma is associated with sleep apnea syndrome

Introduction: In normal-tension glaucoma, optic nerve damage occurs without elevated intraocular pressures, hence vascular and pathogenic mechanisms other than intraocular pressure effects have been postulated. However, the exact cause(s) remain unknown. We have looked for an association between normal-tension glaucoma and sleep apnea syndrome, a disease characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of late cardiovascular and neurological sequelae. Methods: We performed overnight polysomnography in 16 consecutive Caucasian patients with normal-tension glaucoma. The respiratory disturbance index (RDI) during night sleep was used to diagnose and grade obstructive sleep apnea. Patients with an RDI of 10 or more were diagnosed as having obstructive sleep apnea. Results: We observed the following prevalences of obstructive sleep apnea in normal-tension glaucoma patients: 0% (0 of 2) for the group of patients younger than 45 years, 50% (3 of 6) for the age group 45–64 years, and 63% (5 of 8) for the group older than 64 years. Prevalences in the middle and older age group were significantly higher than in a historic control group (p < 0.025 for both, binomial test). Conclusion: Normal-tension glaucoma patients constitute a high-risk population for sleep apnea syndrome. Therefore, they should be screened for sleep apnea syndrome, and, if necessary, be treated to avoid late cardiovascular and neurological sequelae.

Primary open-angle glaucoma is associated with sleep apnea syndrome.

Introduction: The etiology of primary open-angle glaucoma remains unclear. Various risk factors, including vascular abnormalities, have been associated with this disease. Sleep-associated diseases, like sleep apnea syndrome, might also represent a risk factor. Sleep apnea syndrome is characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption with the risk of cardiovascular and neurological sequelae. In this study, we determined the prevalence of sleep apnea syndrome in primary open-angle glaucoma patients. Methods: Overnight transcutaneous finger oximetry was performed in 30 consecutive patients having primary open-angle glaucoma. We assessed the oximetry disturbance index during night sleep, a parameter used to diagnose sleep apnea syndrome and to grade its severity. Results: Sleep apnea syndrome was more prevalent among primary open-angle glaucoma patients compared to normal historic controls of the same age and sex distribution (χ2 = 9.35, d.f. = 3, p < 0.025). The oximetry disturbance index grade was significantly larger in the primary open-angle glaucoma group compared to normal controls (U = 3,352, p = 0.01). According to the oximetry disturbance index, 20% (6/30) of primary open-angle glaucoma patients had sleep apnea syndrome. Conclusion: Primary open-angle glaucoma is associated with sleep apnea syndrome. Early recognition and treatment of sleep apnea syndrome are important to avoid cardiovascular and neurological complications.

Extending lifetime of plastic changes in the human brain

The ability of the brain to adjust to changing environments and to recover from damage rests on its remarkable capacity to adapt through plastic changes of underlying neural networks. We show here with an eye movement paradigm that a lifetime of plastic changes can be extended to several hours by repeated applications of theta burst transcranial magnetic stimulation to the frontal eye field of the human cortex. The results suggest that repeated application of the same stimulation protocol consolidates short‐lived plasticity into long‐lasting changes.