1 April 2003
The Lancet Neurology
Volume 2, Number 4
Figure. Left: T2-weighted MRI showing demyelination at the level of the obex (black arrow) at the medulla oblongata. Right: schematic drawing of the lower brainstem showing the region of demyelinisation (gray area). Nucleus tractus solitarius (NTS), dorsal motor nucleus (DMN), hypoglossal nucleus (XII), trigeminal nucleus (V), medial longitudinal fasciculus (MLF), medial lemniscus (ML), cortical spinal tract (CST), inferior olivary complex (IOC), nucleus ambiguus (NA), inferior cerebellar peduncle (ICP), accessory cuneate nucleus (NC).
2 weeks later she came to the hospital with a similar episode of acute dyspnoea. She recovered, this time after 1 day of invasive ventilation. We gave her methylprednisolone (1g) twice daily. Neurological examination revealed dysarthria, nystagmus, right-sided hemidysaesthesia, and bilateral limb ataxia. T2 MRI showed a slight increase in the size of the brainstem lesion. Exercise and rest myocardial-perfusion imaging showed that perfusion, left ventricular function and volumes, and normal wall motion were normal. A third echocardiogram after stabilisation was completely normal.
This unfortunate young woman with established MS had acute pulmonary oedema. Acute pulmonary oedema can have many causes, including a neurogenic basis.  Neurogenic pulmonary oedema is characterised by acute dyspnoea without concomitant signs of primary lung or cardiac disease. On chest radiography, diffuse alveolar infiltrates are seen, and laboratory analysis often shows lactic acidosis.  For a diagnosis, other possible causes of lung oedema must be excluded, as was done in this case.
Neurogenic pulmonary oedema has been associated with different neurological disorders. Given her medical history, a relapse of MS was thought to be the most likely cause. No other cause for the mild cardiac abnormalities could be found than cerebral or brainstem dysfunction. Indeed, neuroimaging revealed a new lesion corresponding to the site of the nucleus tractus solitarius in the brainstem. Neurogenic pulmonary oedema due to a demyelinating lesion in the caudal part of the brainstem has been recognised before.[3–5]
The pathogenesis of neurogenic pulmonary oedema is uncertain.  Cerebral damage can lead to sympathetic stimulation, resulting in systemic and pulmonary hypertension and cardiac dysfunction with secondary neurogenic pulmonary oedema. Other theories focus on distinct neuroanatomical pathways specifically regulating cardiac function, systemic blood pressure, and pulmonary hydrostatic pressure. The caudal part of the nucleus tractus solitarius, the dorsal motor nucleus of the vagal nerve, and the medial reticular formation are believed to have a role in this system. These nuclei regulate the sympathetic tone of their target organs in response to signals from afferent glossopharyngeal and vagal fibres. Lesions of the nucleus tractus solitarius can lead to high pulmonary pressure with lung oedema. 
This report illustrates that acute pulmonary oedema may be secondary to a lesion of the brainstem. If the diagnostic work-up reveals no underlying pulmonary or cardiac cause, a neurological origin should be considered. Depending on the underlying cause, neurogenic pulmonary oedema can be managed successfully.
1 Samuels MA. Cardiopulmonary aspects of acute neurologic diseases. In: Ropper A.H. (Ed.) 1993; Neurological and neurosurgical internsive care 3rd edn. pp. 103-19. New York: Raven Press
2 Simon RP. Neurogenic pulmonary oedema. Neurol Clin 1993; 11: 309-23. [PubMed]
3 Crawley F, Saddeh I, Barker S, Katifi H. Acute pulmonary ooedema: presenting symptom of multiple sclerosis. Mult Scler 2001; 7: 71-72. [PubMed]
4 Gentiloni N, Schiavino D, Della CF, Ricci E, Colosimo C. Neurogenic pulmonary oedema: a presenting symptom in multiple sclerosis. Ital J Neurol Sci 1992; 13: 435-38. [PubMed]
5 Simon RP, Gean-Marton AD, Sander JE. Medullary lesion inducing pulmonary oedema: a magnetic resonance imaging study. Ann Neurol 1991; 30: 727-30. [PubMed]
MTvdB, WT, and CJV are at the Department of Neurology,
Medical Centre The Hague, The Netherlands. RFV is at the Department of
Cardiology, Medical Centre The Hague, The Netherlands.
© Copyright 2003, Lancet Neurology