Electrophysiological signs of permanent axonal loss in a follow-up study of patients with Guillain-Barré syndrome

Abstract

The neurophysiological mechanisms for persisting impairment of motor function after Guillain-Barre syndrome (GBS) were assessed in 37 unselected patients 1-13 years after diagnosis. For evaluation of reinnervation and axonal loss, macroelectromyography (macro-EMG) including measurement of fiber density (FD) was performed. Data from neuropathy symptom score, neuropathy disability score, nerve conduction studies, and quantitative sensory examination were ranked and summed to a neuropathy rank sum score (NRSS). The isokinetic muscle strength at the ankle was measured. Signs of axonal loss with increase of either macro motor unit potential (macro-MUP) amplitude or FD occurred in 76% of patients. The macro-MUP amplitude correlated with muscle strength and with NRSS. Patients with evidence of residual neuropathy had increased macro-MUP amplitude and FD as well as decreased muscle strength compared to patients without evidence of residual neuropathy. We conclude that axonal loss takes place in a substantial number of GBS patients and is associated with permanent muscle weakness caused by insufficient reinnervation. Possible patterns of pathology are discussed in relation to the macro-EMG findings.

Nerve conduction studies in relation to residual fatigue in Guillain-Barré syndrome

“…In our homogeneous group of AIDP patients, a few, most borderline, abnormal values were found. Most patients showed remarkably good recovery in motor and sensory NC, which was at least in accordance with previous findings [5,10,19].…”

“…Persisting signs of demyelination in our neurologically relatively well-recovered AIDP patients could have led to complaints of fatigue, and the aim of this study was to elucidate its possible underlying mechanisms. It was recently shown that impaired muscle strength of ankle dorsiflexion in GBS during long-term follow-up correlates with axonal damage, and that insufficient functional compensatory reinnervation is found more frequently than persisting signs of demyelination [5]. The relation between residual muscle weakness or axonal damage and complaints of fatigue, however, have not been studied before.…”

“…Based on follow-up studies, in which persisting signs of demyelination were not associated with poor recovery, we considered NC studies potentially relevant [2,5,10,16,19]. Persisting signs of demyelination in our neurologically relatively well-recovered AIDP patients could have led to complaints of fatigue, and the aim of this study was to elucidate its possible underlying mechanisms.…”

“…Little is known about long-term electrophysiological outcome, especially after good neurological recovery. Only in a recent long-term follow-up study, mean 7.0 years after the onset of GBS, was it shown that axonal loss was associated with permanent weakness of the anterior tibial muscle, caused by insufficient reinnervation [5].…”

Nerve conduction studies in Guillain-Barré syndrome: Influence of timing and value of repeated measurements

“…However, because of the evolving nature of nerve damage and possible secondary pathological changes, e.g. secondary axonal damage in AIDP [7,8] or because of critical illness [9], subtype classification can change during the disease course [10]. Furthermore, ganglioside antibodies directed against (para)nodal structures in AMAN can cause conduction failure, which either resolves rapidly or leads to secondary Wallerian-like axonal degeneration.…”