Prevalence of sleep apnoea and capnographic detection of nocturnal hypoventilation in amyotrophic lateral sclerosis.

OBJECTIVE: This retrospective study aimed to investigate whether overnight oxymetry and early morning blood gas analysis predict nocturnal hypoventilation (NH) as reflected by night-time hypercapnia in patients with amyotrophic lateral sclerosis (ALS). In addition, prevalence and clinical determinants of sleep apnoea in ALS were evaluated. METHODS: In 250 patients with non-ventilated ALS, transcutaneous capnometry was performed along with polysomnography or polygraphy and early morning blood gases. RESULTS: 123 patients were female, and 84 patients had bulbar-onset ALS. 40.0% showed NH, and an apnoea-hypopnoea index (AHI) >5/hour was found in 45.6%. In 22.3%, sleep apnoea and NH coincided. The obstructive apnoea index was significantly higher than the central apnoea index (p<0.0001). Both NH and sleep apnoea were significantly more common in male than in female patients. Sleep apnoea and AHI were associated with better bulbar function. Desaturation time (t<90%) and transcutaneous CO2 were negatively correlated with upright vital capacity. Early morning base excess (EMBE), bicarbonate and t<90% were independent predictors of NH. However, among 100 patients with NH, 31 were missed by t<90% >5 min and 17 were not identified when EMBE >3 mmol/L and t<90% >5 min were combined. CONCLUSION: In ALS, sleep apnoea is common and often accompanies NH. It is mainly obstructive, and central apnoea appears to be clinically irrelevant. Polygraphy or oxymetry alone are not sufficient to uncover NH. Combination of EMBE and t<90% may increase sensitivity, but transcutaneous capnography is strongly recommended for reliable detection of NH in patients with ALS.

Upper airway obstruction induced by non-invasive ventilation using an oronasal interface.

BACKGROUND: On initiation of long-term non-invasive ventilation (NIV), intermittent upper airway obstruction has rarely been described as possibly treatment-induced. Inspiratory pressure effects and the use of an oronasal interface may promote obstructive events in some patients with neuromuscular disease (NMD) and amyotrophic lateral sclerosis (ALS) in particular. METHODS: We evaluated clinical data from 212 patients in whom NIV was initiated using an oronasal mask. Treatment-induced upper airway obstruction (TAO) was defined as an AHI > 5/h along with a relative increase of the AHI in the first treatment night compared to diagnostic sleep studies. RESULTS: Prevalence of TAO was 14.2% in the entire cohort, 17.0% in patients with NMD (n = 165), 20.4% in the ALS subgroup (n = 93), and 4.3% in non-NMD patients (n = 47). Fixed expiratory positive airway pressure (EPAP, n = 192) was significantly correlated with AHI reduction (r = 0.50; p < 0.001). The inspiratory-expiratory pressure interval (∆PAP, n = 191) showed inverse correlation with the AHI change achieved in the first treatment night (r = - 0.28; p < 0.001). However, ∆PAP and the effective pressure range between EPAP and the highest inspiratory PAP achieved were not predictive of TAO. In patients with ALS, TAO was associated with better bulbar function. Study results were limited by initial EPAP being significantly lower in NMD patients reflecting that sleep apnea was less frequent and severe in this subgroup. CONCLUSIONS: Initiation of NIV using an oronasal interface may be associated with TAO in a subset of patients. Since both EPAP and ∆PAP appear to play a causative role, careful titration of ventilator settings is recommended.

Sleep disorders in Charcot-Marie-Tooth disease type 1.

INTRODUCTION: Obstructive sleep apnoea (OSA) and restless legs syndrome (RLS) have been reported in Charcot-Marie-Tooth disease (CMT) type 1A and axonal subtypes of CMT, respectively. The aim of this case-control study was to investigate both prevalence and severity of OSA, RLS and periodic limb movements in sleep (PLMS) in adult patients with genetically proven CMT1. PATIENTS AND METHODS: 61 patients with CMT1 and 61 insomnic control subjects were matched for age, sex, and Body Mass Index. Neurological disability in patients with CMT was assessed using the Functional Disability Scale (FDS). RLS diagnosis was based on a screening questionnaire and structured clinical interviews. All participants underwent overnight polysomnography. RESULTS: OSA was present in 37.7% of patients with CMT1 and 4.9% of controls (p<0.0001). The mean Apnoea Hypoponea Index (AHI) was significantly higher in patients with CMT1 than in control individuals (9.1/h vs 1.2/h). RLS was present in 40.9% of patients with CMT1 and in 16.4% of controls (p<0.001). In the CMT1 group, OSA was significantly more common in men and RLS in women. The AHI correlated with both age and the FDS score, the latter being a significant independent predictor of OSA. PLMS were found in 41.0% of patients with CMT1, but were not correlated with measures of sleep quality. CONCLUSIONS: In addition to known risk factors, CMT may predispose to OSA. RLS is highly prevalent not only in axonal subtypes of CMT but also in primarily demyelinating subforms of CMT. PLMS are common in CMT1, but do not significantly impair sleep quality.

Continuous positive airway pressure ventilation for acute ischemic stroke: a randomized feasibility study.

BACKGROUND AND PURPOSE: Sleep-related breathing disorders occur frequently after stroke. We assessed the feasibility of continuous positive airway pressure (CPAP) treatment initiated in the first night after stroke. METHODS: In this open-label, parallel-group trial, 50 patients were randomly assigned to the CPAP therapy or to the control group. All patients underwent polysomnography in the fourth night. Intervention patients received CPAP therapy for 3 nights starting the first night after stroke onset and for an additional 4 nights when polysomnography revealed an apnea-hypopnea index >10/hour. The primary end point was feasibility defined as apnea-hypopnea index reduction under CPAP treatment, nursing workload, and CPAP adherence. RESULTS: The apnea-hypopnea index under CPAP treatment was significantly reduced (32.2±25.3-9.8±6.6, P=0.0001). Nursing workload did not significantly differ between the CPAP (n=25) and the control group (n=25; P=0.741). Ten patients (40.0%) had excellent CPAP use, 14 patients (56.0%) had some use, and 1 patient (4.0%) had no use. There was a trend toward greater National Institutes of Health Stroke Scale score improvement until Day 8 in patients on CPAP (2.00 versus 1.40, P=0.092) and a significantly greater National Institutes of Health Stroke Scale score improvement in patients with excellent CPAP use when compared with control patients (2.30 versus 1.40, P=0.022). CONCLUSIONS: CPAP therapy initiated in the first night after stroke seems to be feasible and was not associated with neurological deterioration. Clinical Trial Registration- URL: www.clinicaltrials.gov. Unique identifier: NCT00151177.

Treatment for obstructive sleep apnoea: effect on peripheral nerve function.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea (OSA) is suggested to be associated with peripheral nerve damage. A case-control study was conducted to provide further support to this observation. In a longitudinal intervention study, it was examined whether treatment for OSA has a possible beneficial effect on peripheral nerve function. METHODS: Participants were 23 patients with OSA and 23 controls matched for age and body mass index (BMI), all without any known cause of peripheral nerve damage. The sensory nerve action potential (SNAP) amplitudes of both sural nerves were determined. After 6 months of treatment for OSA, treatment compliance was evaluated and nerve conduction studies were repeated. RESULTS: Patients with OSA had significantly lower mean (standard deviation) sural SNAP amplitudes than controls (6.3 (3.5) v 11.2 (5.0), p < 0.001). Multivariate regression analysis including the variables age, BMI and Apnoea-Hypopnea Index (AHI) showed that both age (p < 0.01) and AHI (p < 0.05) were inversely related to the SNAP amplitude. On follow-up, the sural SNAP showed an increase of 2.6 mV on average (p < 0.001). Multivariate regression analysis including the variables age, BMI, AHI, pretreatment SNAP and treatment compliance identified only treatment compliance as being significantly related to the SNAP increase (p < or = 0.005). CONCLUSION: OSA is an independent risk factor for axonal dysfunction of peripheral sensory nerves. Impaired neural function is at least partly reversible with treatment for sleep apnoea.

Painless legs and moving toes in a mother and her daughter.

Painful legs and moving toes (PLMT) is a rare syndrome which is characterised by involuntary movements of the toes and pain in the legs. We report on a mother and her daughter who both presented with involuntary movements of the toes similar to those seen in PLMT but without any associated pain. Neurological examination revealed intermittent 0.3 to 0.5-Hz flexion and extension of the toes and ankles of the right foot in the mother, and of both feet in the daughter. In both patients, the movements appeared during periods of rest that were uncorrelated with the time of day. Diagnostic work-up gave no evidence of radiculopathy or of focal neuropathy. Overnight polysomnography documented that movements of the toes and feet occurred only before sleep onset and during periods of nocturnal awakening or arousals. Because the movements observed in our patients were similar to those seen in patients with PLMT, we diagnosed an abortive form of this syndrome, which already has got the naming "painless legs and moving toes." The occurrence in a mother and her daughter may point to a hereditary component of this disorder.