QJM Advance Access originally published online on February 2, 2008
QJM 2008 101(3):245-247; doi:10.1093/qjmed/hcn005
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Respiratory muscle weakness in a patient with quiescent Crohn's disease and pneumonia
Sir,A 33-year-old woman presented with a week's history of progressive backache, weakness and dysphagia. The onset of her symptoms coincided with tapering of 4-week course of oral corticosteroids (prednisolone), which was instituted to treat a severe pneumonic illness requiring admission to intensive care and a short period of assisted ventilation. She did not have any previous history of obstructive airways or interstitial pulmonary disease. Her respiratory illness was presumed to be due to viral pneumonia but no serological or microbiological evidence for infection was identified. She was diagnosed with Crohn's disease since as a child, based on histology of her colonoscopic biopsy. The bowel disease was quiescent for many years and she was essentially asymptomatic for Crohn's disease at presentation. She also suffered from asthma, which was well controlled on regular use of inhaled steroids and beta agonists.
On this occasion, she had developed progressive muscle weakness. She could not roll over in bed, lift her arms or rise. She also noted difficulty with swallowing both liquids and solids. Clinical examination at the Accident and Emergency department showed mild bifacial weakness, dysarthria and weak cough. She was tachypnoeic with a respiratory rate of 25 breaths per minute. Limb examination revealed globally flaccid tone and profound proximal weakness (MRC 1/5). Forced vital capacity was <1 l and arterial blood gas examination showed a PaO2 on air of 8.9 kPa (11.10–14.4 kPa). She was transferred to the intensive care unit for intubation and assisted ventilation. The medical team suspected a diagnosis of acute inflammatory demyelinating polyneuropathy (Guillain–Barre syndrome).
On the following morning, when she was seen by us, she was still being ventilated but was off all sedation and muscle relaxants. She had no skin rash, keratosis or arthropathy. Examination revealed severe weakness in her neck flexors, bifacial and bulbar muscles and proximal limb muscles. Her eye movements and sensory examination were normal. The tendon reflexes were easily elicited and plantar responses were flexor. The persistence of tendon reflexes was considered to be incompatible with the severity of muscle weakness in a ventilated patient with presumed Guillain–Barre syndrome and a diagnosis of polymyositis was preferred. The clinical diagnosis of polymyositis was supported by marked elevation of her serum creatinine kinase (CK) of 3319 IU/l (normal less than 145) and ESR of 115 mm/h (normal less than 15). She was commenced on a course of intravenous methylprednisolone (1 g/day for 3 days), followed by oral prednisolone (1 mg/kg/day; total dose 80 mg daily) and alendronic acid (70 mg/week) for osteoprotection.
Subsequent investigations confirmed the clinical diagnosis of acute polymyositis. Electromyography (EMG) showed insertional activity, myopathic potentials characterized by short-duration, low-amplitude polyphasic units on voluntary activation, increased spontaneous activity with fibrillations, complex repetitive discharges and positive sharp waves, all of which were consistent with an inflammatory myopathy. There was no motor nerve conduction block, sensory studies were normal and repetitive motor nerve stimulation showed no evidence of neuromuscular junction dysfunction. Histological examination of a needle muscle biopsy taken from her left quadriceps muscle revealed evidence of lymphocytic infiltration and muscle fibre necrosis with no perifascicular muscle atrophy (Figure 1), appearances in keeping with her diagnosis of polymyositis. Cerebrospinal Fluid (CSF) biochemical and cytological examination was normal. Serum and CSF electrophoresis revealed paired oligoclonal bands, consistent with a systemic immune response. Serological screening was positive for anti-Jo-1 antibodies. An elevated serum troponin T of 1.01 g/l (less than 0.01) was found; however, electrocardiographic appearances were unremarkable apart from sinus tachycardia. Echocardiographic examination showed normal left ventricular function (Ejection Fraction >55%). Abdominal ultrasound examination showed mild fatty hepatic infiltration and normal renal anatomy.
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She experienced a rapid clinical improvement with steroid treatment. She was successfully extubated on the 4th day of high dose prednisolone given by nasogastric tube. Recovery of motor function began after 7 days of steroid treatment, accompanied by a corresponding decline in serum CK levels. Dysphagia resolved after 2 weeks. She continued to enjoy a good recovery of power and function in her limbs, and was discharged 10 weeks after initiation of steroid therapy with mild, residual proximal weakness in her lower limbs (MRC grade 4) and a marginally high serum CK (540 IU/l). Her steroids were tailed off after 3 months by 5 mg/fortnight and the treatment was successfully withdrawn without any relapse of her muscle weakness. Her follow up at the end of 12 months showed complete recovery of motor function, which was maintained at the end of 18 months without any treatment.
Discussion
We describe a patient who developed neuromuscular paralysis subacutely over days at the time of steroid withdrawal for a severe interstitial pneumonia. Clinically, a diagnosis of generalized inflammatory myopathy due to acute polymyositis was favoured over acute inflammatory demyelinating neuropathy (Guillain–Barre syndrome) because of preserved tendon reflexes despite severe muscle weakness requiring ventilatory support. Tendon reflexes may be retained in the early phase of an evolving Guillian–Barre syndrome but persistence of normal tendon reflexes in a severely paralysed limb would be highly unlikely. Modest rises of serum CK may accompany occasional cases of inflammatory neuropathy because of intramuscular nerve injury and acute muscle denervation but the high level of serum CK as observed in this case would be most unusual. The clinical diagnosis of acute polymyositis in our patient was subsequently confirmed by her EMG and muscle histology. However, it is important to emphasize that treatment decision in acute neuromuscular paralysis should not be postponed because of possible delays with electrophysiological testing in a critically ill patient.
In this case, polymyositis was probably unmasked by the withdrawal of corticosteroids to which it is widely known to be responsive.1,2 Inflammatory myopathy is a rare but recognized association of Crohn's disease,3 but there was no clinical evidence of active colitis in the patient we report. The finding of positive anti-Jo1 antibody suggests that the pneumonitis in this case was probably the initial manifestation of anti-synthetase syndrome. Anti- Jo-1 antibodies are directed against histidyl transfer ribonucleic acids (tRNA) synthetase, a cytoplasmic enzyme, which acetylates tRNA.4 It is present in 20% of patients with polymyositis 5 and is associated with intercurrent interstitial lung disease.6 Anti-synthetase syndrome was first reported by Marguerie and others in 1980 to describe a population of patients with polymyositis, interstitial lung disease and positive anti-Jo-1 antibodies in the serum.7 Other manifestations of this syndrome include mechanic's hands (hyperkeratosis on the lateral aspects of the digits), non-erosive arthropathy and sicca syndrome, which were absent in our patient.
Department of Neurology and
Department of Neuropathology
Essex Centre for Clinical Neurosciences
Queen's Hospital
Rom Valley Way
Romford
Essex RM7 0AG
UK
email: chaudhuria{at}gmail.com
References
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3. Menard DB, Haddad H, Blain JG, Beaudry R, Devroede G, Masse S. Granulomatous myositis and myopathy associated with crohn's colitis. N Engl J Med (1976) 295:818–9.[Web of Science][Medline]
4. Mathews MB, Bernstein RM. Myositis autoantibody inhibits histidyl-tRNA synthetase: a model for autoimmunity. Nature (1983) 304:177–9.[CrossRef][Medline]
5. Dalakas MC, Hohlfeld R. Polymyositis and dermatomyositis. Lancet (2003) 362:971–82.[CrossRef][Web of Science][Medline]
6. Fathi M, Dastmalchi M, Rasmussen E, Lundberg IE, Tornling G. Interstitial lung disease, a common manifestation of newly diagnosed polymyositis and dermatomyositis. Ann Rheum Dis (2004) 63:297–301.
7. Marguerie C, Bunn CC, Beynon HL, Bernstein RM, Hughes JM, So AK, et al. Polymyositis, pulmonary fibrosis and autoantibodies to aminoacyl-tRNA synthetase enzymes. Q J Med (1990) 77:1019–38.[Web of Science][Medline]
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