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In this letter we comment on the publication of Yuki and Hirata who postulate a possible relation between critical illness polyneuropathy and axonal Guillain-Barré syndrome.1 The authors mentioned a nosological relation, which at that time still had to be demonstrated by the presence of antiganglioside antibodies in the serum of patients with critical illness polyneuropathy. Critical illness polyneuropathy is a neuromuscular disorder that has been recognised in critically ill patients.2 The clinical picture consists of difficulty in weaning from the artificial respirator, tetraparesis, and muscle wasting of the limbs. The tendon reflexes are mostly decreased or absent. The neurophysiological examination shows an axonal polyneuropathy and sometimes myopathic altered motor unit potentials. The morphological features in the nerve point to a primarily distal axonal degeneration of motor and sensory fibres. Muscle biopsy shows scattered atrophic fibres in acute denervation and grouped atrophy in chronic denervation. Also, necrotic muscle fibres can be found suggesting the contribution of a myopathy or a primary myopathy.3 On clinical and electrodiagnostic grounds neuromuscular complications in the critically ill patients may be due to a polyneuropathy or myopathy. Because it is not always possible to differentiate between an axonal motor neuropathy and myopathy, we prefer to use the descriptive term critical illness polyneuropathy and myopathy (CIPNM).
To test the hypothesis of Yuki and Hirata we studied the serum of eight patients obtained during the acute phase of CIPNM and from two controls, which were patients that were also on the artificial respirator and critically ill. In all 10 patients sepsis or systemic inflammatory response syndrome occurred. The serum samples were tested for IgG and IgM reactivity against gangliosides GM1 and GD1a. In none of these samples could any reactivity be detected. Therefore, it is unlikely that in these Dutch patients with CIPNM, axonal damage is mediated through anti-GM1 or anti-GD1a antibodies as was suggested by the authors.
To distinguish CIPNM from the acute motor axonal variant of Guillain-Barré syndrome the following characteristics may be useful:
Guillain-Barré syndrome is the primary neurological reason of admission on the intensive care unit; CIPNM on the other hand develops during a patient's stay on the intensive care unit for another reason
Infectious symptoms such as fever and diarrhoea have usually subsided before the clinical features of Guillain-Barré syndrome appear
The characteristic alterations in the CSF of patients with Guillain-Barré syndrome, with a raised protein and normal to slightly increased cell count
The possibility of detecting IgG anti-bodies against GM1, GM1b, GD1a, and Ga1Nac-GD1a as immunological markers in the serum of patients with axonal Guillain-Barré syndrome.
Electrodiagnostic changes in Guillain-Barré syndrome occur in both sensory and motor nerves in about 80% of the patients in the western world. In CIPNM there is a predominantly motor dysfunction in both the clinical and electrodiagnostic evaluations.
During the progression of Guillain-Barré syndrome the demyelinating features of the nerve conduction study may change into a secondary axonal pattern. In axonal Guillain-Barré syndrome slow nerve conduction velocity remains in some patients and the initial needle EMG study lacks spontaneous activity.4 In CIPNM phrenic nerve conduction studies usually show no significantly prolonged latencies.5
Severe autonomic disturbances are more common in patients with Guillain-Barré syndrome after the polyneuropathy has developed than in patients with CIPNM.5
Critical illness polyneuropathy, a complication of sepsis and multiple organ failure, may be a common cause of the difficulty of weaning patients in critical care units from the ventilator.1-1 Its aetiology has yet to be determined and needs to be clarified to treat such patients more effectively. Critical illness polyneuropathy and Guillain-Barré syndrome are both monophasic illnesses of acute onset, characterised by limb weakness and areflexia. Whereas classic pathological studies of Guillain-Barré syndrome show demyelination and inflammatory infiltrates in peripheral nerves, electrophysiological and pathological studies of critical illness polyneuropathy show the presence of primary axonal degeneration of the peripheral nerves but no evidence of inflammation. The two types of polyneuropathies, therefore, have been considered separate entities, but recent pathological studies have established that there is a primary axonal form of Guillain-Barré syndrome. We mentioned that axonal Guillain-Barré syndrome should be the diagnosis for some patients with critical illness polyneuropathy, and that investigation of the presence of serum IgG antibodies against GM1, GM1b, GD1a, or GalNAc-GD1a (possible immunological markers for axonal Guillain-Barré syndrome) in patients with critical illness polyneuropathy should help test this hypothesis.1-2
I deeply appreciate de Letter et alfor testing our hypothesis. Some patients with Guillain-Barré syndrome who do carry either anti-GM1 or anti-GD1a IgG antibodies, however, have anti-GM1b, anti-GalNAc-GD1a antibodies, or both.1-3 1-4 I am willing to investigate anti-GM1b and anti-GalNAc-GD1a IgG antibodies in their patients with critical illness polyneuropathy. Further examinations using many more serum samples as well as the additional markers are necessary to reject our hypothesis. If some patients with critical illness polyneuropathy do have those autoantibodies, they would benefit from intravenous immunoglobulin therapy,1-5 which is also useful for treating the sepsis associated with critical illness polyneuropathy.
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