Spirometry is the most common test recommended to monitor respiratory dysfunction in patients of amyotrophic lateral sclerosis (ALS). However, the test depends on the patient's efforts and may be difficult to conduct in patients with faciobulbar weakness. We aimed to study the role of phrenic nerve-electrophysiological studies to predict respiratory dysfunction and correlate it with the forced vital capacity (FVC) in patients of ALS.
Forty-three unselected patients (32 male, 25 with limb-onset ALS, age 50±15 years) with clinically definite or probable ALS were included. They were evaluated at entry and after a period of 6 months with the ALS functional rating scale (ALSFRS), their respiratory subscores (ALS-FRSr), their FVC values as determined by spirometry, and phrenic nerve studies.
Six patients could not perform a satisfactory spirometry at the onset and during the course of illness. All the six patients had severe faciobulbar weakness. Respiratory abnormalities on spirometry were found in 85% of patients, whereas only 30% were symptomatic for respiratory dysfunction. In patients with severe respiratory dysfunction (FVC<60%), the phrenic nerve motor amplitudes (PNAMPs) were significantly reduced compared to those with mild-to-moderate respiratory dysfunction (FVC≥60%). The FVC value showed a significant correlation with the PN-AMP. Nine patients had a poor outcome (death or severe disability) at the end of a period of 6 months. Low levels of both FVC and PN-AMP were predictors of poor outcome for patients at the end of 6 months.
We conclude that respiratory dysfunction, as determined by spirometry, is common in patients of ALS. However, only about one-third of patients show symptoms of respiratory distress. Clinical symptoms of respiratory distress are unreliable predictors of respiratory failure in ALS. Measurement of PN-AMP at the time of presentation may be an additional tool to assess respiratory dysfunction in ALS. Reduced PN-AMP values may be indicative of low FVC and may have some role in the assessment of respiratory function in patients in whom a routine spirometry is not possible due to limitations arising from the illness. Both low FVC and reduced PN-AMP at the time of presentation are predictors of poor outcome for patients at the end of 6 months.
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- Amyotrophic lateral sclerosis.N Engl J Med. 2001; 344: 1688-1700
- Management of respiration in MND/ALS patients: an evidence based review.Amyotroph Lateral Scler. 2006; 7: 5-15
- Motor neuron disease presenting with respiratory failure.J Neurol Sci. 1996; 139 (Suppl): 117-122
- Consensus guidelines for the design and implementation of clinical trials in ALS. World Federation of Neurology committee on research.J Neurol Sci. 1999; 169: 2-12
- Practice parameter: the care of the patient with amyotrophic lateral sclerosis (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology: ALS practice parameters task force.Neurology. 1999; 52: 1311-1323
- Spirometry in amyotrophic lateral sclerosis.Arch Neurol. 1979; 36: 74-80
- Forced vital capacity (FVC) as an indicator of survival and disease progression in an ALS clinic population.J Neurol Neurosurg Psychiatry. 2006; 77: 390-392
- Respiratory muscle strength and ventilatory failure in amyotrophic lateral sclerosis.Brain. 2001; 124: 2000-2013
- Predicting respiratory insufficiency in amyotrophic lateral sclerosis: the role of phrenic nerve studies.Clin Neurophysiol. 2009; 120: 941-946
- World Federation of Neurology research group on motor neuron diseases. El Escorial revisited: revised criteria for the diagnosis of amyotrophic lateral sclerosis.Amyotroph Lateral Scler Other Motor Neuron Disord. 2000; 1: 293-299
- An evaluation of neurophysiological criteria used in the diagnosis of motor neuron disease.J Neurol Neurosurg Psychiatry. 2010; 81: 646-649
- The ALSFRS-R: a revised ALS functional rating scale that incorporates assessments of respiratory function. BDNF ALS Study Group (Phase III).J Neurol Sci. 1999; 169: 13-21
- Electrodiagnostic assessment of respiratory dysfunction in motor neuron disease.in: Eisen A. Handbook of clinical neurophysiology vol. 4. Elsevier B.V., 2004: 513-528
- Changes in the normal maximal expiratory flow-volume curve with growth and aging.Am Rev Respir Dis. 1983; 127: 725-734
- Single-breath carbon monoxide diffusing capacity (transfer factor). Recommendations for a standard technique—1995 update.Am J Respir Crit Care Med. 1995; 152: 2185-2198
- Use of respiratory function tests to predict survival in amyotrophic lateral sclerosis.Amyotroph Lateral Scler. 2010; 11: 194-202
- Pulmonary function at diagnosis of amyotrophic lateral sclerosis: rate of deterioration.Chest. 1993; 103: 508-513
- Spirometry in the supine position improves the detection of diaphragmatic weakness in patients with amyotrophic lateral sclerosis.Chest. 2002; 121: 436-442
- Amyotrophic lateral sclerosis (ALS): evaluation of respiratory function.Rev Neurol (Paris). 2006; 162 ([Article in French]): 437-444
- Assessment of pulmonary function in amyotrophic lateral sclerosis.Indian J Chest Dis Allied Sci. 2009; 51: 87-91
- The respiratory system in neuromuscular disorders.in: Macklem P.T. Roussos C. The thorax. Marcel Dekker, New York1995: 2177-2212
- Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosis.Acta Neurol Scand. 2010; 121: 400-405
- Chronic respiratory failure in patients with neuromuscular diseases: diagnosis and treatment.J Bras Pneumol. 2007; 33: 81-92
- Life satisfaction of individuals with Duchenne muscular dystrophy using long-term mechanical ventilatory support.Am J Phys Med Rehabil. 1991; 70: 129-135
- Pulmonary predictors of survival in amyotrophic lateral sclerosis: use in clinical trial design.Muscle Nerve. 2006; 33: 127-132
- Respiratory systems abnormalities and clinical milestones for patients with amyotrophic lateral sclerosis with emphasis upon survival.Amyotroph Lateral Scler. 2007; 8: 36-41
- Phrenic nerve conduction studies.Muscle Nerve. 1992; 15: 597-603
- Phrenic nerve conduction in amyotrophic lateral sclerosis.J Neurol Sci. 1995; 129 (Suppl): S35-S37
- Phrenic nerve conduction in normal subjects.Muscle Nerve. 1995; 18: 330-335
- Changes of the phrenic nerve motor response in amyotrophic lateral sclerosis: longitudinal study.Clin Neurophysiol. 2009; 120: 2082-2085
Published online: April 15, 2011
Accepted: March 24, 2011
Received in revised form: March 19, 2011
Received: November 27, 2010
© 2011 Elsevier B.V. Published by Elsevier Inc. All rights reserved.