Acute Motor Axonal Neuropathy
Introduction[edit | edit source]
Acute motor axonal neuropathy (AMAN) is classified as a subtype of Guillain–Barré syndrome (GBS)[1]. The disease was first discovered in China and was nicknamed 'chinese paralytic disease'[1]. AMAN is the most common cause of flaccid paralysis in China[2]. Pathology in AMAN patients are usually limited to the motor nerve, with macrophages destroying axons while myelin remains intact, a contrast to AIDP GBS (most common form of GBS) which is known as a demyelinating disease[1]. While AMAN mainly involves axonal damage to motor nerve fibres; acute inflammatory demyelinating polyradiculoneuropathy (AIDP) involves both motor and sensory nerve fibre damage due to demyelination[1].
AMAN has an estimated prevalence of 30–65% in Asia, Central and South America[3].
Aetiology[edit | edit source]
- AMAN is strongly linked to Campylobacter jejuni and Zika virus infection.[4][5]
- AMAN has some documented association with hepatitis E infection.[6]
Pathogenesis[edit | edit source]
GBS is a post-infectious disorder with two-thirds of patients presenting symptoms of a respiratory or gastrointestinal tract infection before the onset of GBS[7].
Serum antibodies against GM1a, GM1b, GD1a and GalNAc-GD1a gangliosides are noticeable in patients with AMAN[8]. Studies have also shown complement activation causing nerve degeneration at the nodes of Ranvier and at the motor nerve terminal in a mouse model of AMAN.[9]
Clinical features[edit | edit source]
AMAN presents similarly in terms of clinical features as well as CSF findings to GBS:[1]
- Weakness of limbs (earliest symptom is weakness of lower limbs)
- Weakness of respiratory muscles
- Gradual weakening and finally, absence of tendon reflexes
- Bulbar palsy in 61% of patients[1]
- Autonomic dysfunction and pain[10]
However, it generally presents without any sensory symptoms, unlike AIDP-GBS[6], although it can present with sensory symptoms[11]. A neurophysiological screen in patients with AMAN should also show no evidence of demyelination, unlike GBS[6].
Differential Diagnosis[edit | edit source]
The differential diagnosis of GBS- AMAN should rule out:
- infectious diseases
- malignancy
- disorders of the neuromuscular junction
- spinal root inflammation due to cytomegalovirus or HIV
- transverse myelitis
- Lyme disease
A lumbar puncture is recommended to rule out diagnoses other than GBS- elevated protein level and normal cell counts in the CSF (termed albuminocytological dissociation) is considered a hallmark of GBS.
EMG-NCV studies also help to diagnose GBS as well as assist in identifying the subtype of the condition (AMAN, AIDP). AMAN patients tend to show decreased motor and/or sensory amplitudes , and complex neurophysiological findings with transient conduction block or slowing, which rapidly recovers during the course of the disease—a phenomenon called reversible conduction failure.[8]
The prevalence of pain can help differ between the subtypes of GBS[12] - many patients with AMAN also experience back and neck pain[13].
Prognosis[edit | edit source]
The prognosis of AMAN is worse compared to the other subtypes of GBS[14][15].
Medical Management[edit | edit source]
Medical management for AMAN combines multidisciplinary supportive medical care and immunotherapy. IVIg and plasma exchange have pleiotropic immunomodulatory effects and are considered primary treatment measures[16].
Studies have shown that patients with AMAN had better outcomes after plasma exchange than after IVIg therapy, and that plasma exchange was also the most cost-effective option[17]. Economically challenged countries have the option of small-volume plasma exchange or exchange transfusion as a low-cost therapeutic option.[17]
Physiotherapy Management[edit | edit source]
Physical therapy has shown a lot of improvement with pain management and neuromuscular efficiency. Physical therapy modalities of massage and relaxation, proprioceptive neuromuscular facilitation have shown to have positive results. [18]
Additional Details can be found on the GBS page.
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lv J, Zhaori G. Collaborative studies of U.S.–China neurologists on acute motor axonal neuropathy Pediatric Investig. 2022 Mar 22;6(1):1-4.
- ↑ McKhann GM, Cornblath DR, Griffin JW, Ho TW, Li CY, Jiang Z, Wu HS, Zhaori G, Liu Y, Jou LP, Liu TC. Acute motor axonal neuropathy: a frequent cause of acute flaccid paralysis in China. Annals of neurology. 1993 Apr;33(4):333-42.
- ↑ Van den Berg B, Walgaard C, Drenthen J, Fokke C, Jacobs BC, Van Doorn PA. Guillain–Barré syndrome: pathogenesis, diagnosis, treatment and prognosis. Nature Reviews Neurology. 2014 Aug;10(8):469-82.
- ↑ Ho TW, Mishu B, Li CY, Gao CY, Cornblath DR, Griffin JW, Asbury AK, Blaser MJ, McKhann GM. Guillain-Barre syndrome in northern China Relationship to Campylobacter jejuni infection and anti-glycolipid antibodies. Brain. 1995 Jun 1;118(3):597-605.
- ↑ Watrin L, Ghawché F, Larre P, Neau JP, Mathis S, Fournier E. Guillain–Barré syndrome (42 cases) occurring during a Zika virus outbreak in French Polynesia. Medicine. 2016 Apr 1;95(14):e3257.
- ↑ 6.0 6.1 6.2 Al-Saffar A, Al-Fatly B. Acute Motor Axonal Neuropathy in Association with Hepatitis E. Front Neurol. 2018 Feb 9;9:62. doi: 10.3389/fneur.2018.00062. PMID: 29479336; PMCID: PMC5811470.
- ↑ Kuwabara S, Yuki N. Axonal Guillain-Barré syndrome: concepts and controversies. The Lancet Neurology. 2013 Dec 1;12(12):1180-8.
- ↑ 8.0 8.1 Kuwabara S, Yuki N. Axonal Guillain-Barré syndrome: concepts and controversies. The Lancet Neurology. 2013 Dec 1;12(12):1180-8.
- ↑ Hafer‐Macko C, Hsieh ST, Ho TW, Sheikh K, Cornblath DR, Li CY, McKhann GM, Asbury AK, Griffin JW. Acute motor axonal neuropathy: an antibody‐mediated attack on axolemma. Annals of Neurology: Official Journal of the American Neurological Association and the Child Neurology Society. 1996 Oct;40(4):635-44.
- ↑ Yuki N, Hartung HP. Guillain–barré syndrome. New England Journal of Medicine. 2012 Jun 14;366(24):2294-304.
- ↑ Sekiguchi Y, Uncini A, Yuki N, Misawa S, Notturno F, Nasu S, Kanai K, Noto YI, Fujimaki Y, Shibuya K, Ohmori S. Antiganglioside antibodies are associated with axonal Guillain–Barré syndrome: a Japanese–Italian collaborative study. Journal of Neurology, Neurosurgery & Psychiatry. 2012 Jan 1;83(1):23-8.
- ↑ Ruts L, Drenthen J, Jongen JL, Hop WC, Visser GH, Jacobs BC, Van Doorn PA, Dutch GBS Study Group. Pain in Guillain-Barre syndrome: a long-term follow-up study. Neurology. 2010 Oct 19;75(16):1439-47.
- ↑ McKhann GM, Cornblath DR, Ho T, Griffin JW, Li CY, Bai AY, Wu HS, Yei QF, Zhang WC, Zhaori Z, Jiang Z. Clinical and electrophysiological aspects of acute paralytic disease of children and young adults in northern China. The Lancet. 1991 Sep 7;338(8767):593-7.
- ↑ Zhang Y, Zhao Y, Wang Y. Prognostic factors of Guillain-Barré syndrome: a 111-case retrospective review. Chin Neurosurg J. 2018 Jun 18;4:14. doi: 10.1186/s41016-018-0122-y. PMID: 32922875; PMCID: PMC7398209.
- ↑ Seta T, Nagayama H, Katsura K, Hamamoto M, Araki T, Yokochi M, Utsumi K, Katayama Y. Factors influencing outcome in Guillain-Barré Syndrome: comparison of plasma adsorption against other treatments. Clin Neurol Neurosurg. 2005 Oct;107(6):491-6. doi: 10.1016/j.clineuro.2004.12.019. PMID: 16202823.
- ↑ Hughes RAC, Swan AV, van Doorn PA. Intravenous immunoglobulin for Guillain‐Barré syndrome. Cochrane Database of Systematic Reviews 2012, Issue 7. Art. No.: CD002063. DOI: 10.1002/14651858.CD002063.pub5. Accessed 09 May 2024.
- ↑ 17.0 17.1 Netto AB, Kulkarni GB, Taly AB, Rao GU, Periyavan S, Rao S. A comparison of immunomodulation therapies in mechanically ventilated patients with Guillain Barré syndrome. Journal of Clinical Neuroscience. 2012 Dec 1;19(12):1664-7.
- ↑ Shang P, Feng J, Wu W, Zhang HL. Intensive care and treatment of severe Guillain–Barré syndrome. Frontiers in Pharmacology. 2021 Apr 27;12:608130.
