Short paper Diaphragm thickness and inspiratory strength in patients with Duchenne muscular dystrophy

muscle groups. Recently, high resolution ultrasound scanning has been used to assess diaBackground – There is little information on the morphometric characteristics of phragm thickness during tidal breathing and during relaxation in normal subjects. 6 Using the diaphragm in patients with Duchenne muscular dystrophy. B mode ultrasonography we have imaged the costal portion of the diaphragm both at rest Methods – The thickness of the diaphragm was measured at the zone of apposition and during maximum voluntary contractions in normal subjects. In this paper we have made using B mode ultrasonography in 10 boys with Duchenne muscular dystrophy of ultrasonographic measurements of diaphragm thickness in young patients with Duchenne mean (SD) age 10.3 (1.3) years and 12 normal controls of mean (SD) age 11.3 muscular dystrophy and age matched normal boys. (2.0) years during relaxation (DiTrelax) and during maximum effort inspiratory manoeuvres (DiTPmax) at functional residual capacity. Methods Results – DiTrelax was greater in the  patients with Duchenne muscular dysTen boys with Duchenne muscular dystrophy trophy (1.74 (0.21) mm) than in controls (mean age 10.3, range 7–12 years, mean body (1.48 (0.20) mm), mean difference (95% weight 103.4% of ideal, mean height 97.3% of CI) 0.26 (0.08 to 0.44), despite considerable predicted values) who regularly attended the impairment of maximum effort inHammersmith Hospital Muscle Clinic took spiratory mouth pressure (Pmax) part in the study. The upper age limit was set (patients with Duchenne muscular dyson the basis of preliminary ultrasound studies trophy −37 (8) cm H2O, controls −80 carried out in four boys aged 14–17 years with (33) cm H2O), mean difference (95% CI) Duchenne muscular dystrophy which allowed 43 (65 to 20). During a Pmax manoeuvre, no clear visualisation of the diaphragm (see compared with measurements taken durdiscussion). All patients had progressive, preing relaxation, the diaphragm thickened dominantly proximal, muscular weakness with1.6 times in patients with Duchenne musout sensory abnormalities which had developed cular dystrophy and 2.3 times in controls before the age of five and enlarged calves or (DiTPmax 2.62 (0.7) mm and 3.5 Achilles tendon contractures, or both. Two (0.85) mm, respectively), mean difference boys were confined to a wheel chair. They all (95% CI) −0.88 (−1.58 to −0.18). had serum creatine kinase levels, electroConclusions – Resting diaphragm thickDepartments of myographic and muscle biopsy findings Medicine and ness is increased in young patients with consistent with the diagnosis of Duchenne Paediatrics, Royal Duchenne muscular dystrophy with immuscular dystrophy, and had no respiratory Postgraduate Medical paired respiratory muscle force. This School, Hammersmith symptoms. Twelve normal boys (mean age Hospital, London finding could be analogous to the pseudo11.3, range 6–12 years, mean body weight W12 0NN, UK hypertrophy that is observed in some limb 103.0% of ideal, mean height 98.6% of preP F De Bruin muscle groups. dicted values) were studied as controls. J Ueki A Bush (Thorax 1997;52:472–475) Y Khan A Watson