Acute Motor Axonal Neuropathy (AMAN), a Variant of Guillain-Barre Syndrome: A Case Study

Abstract

This case study documents a fictional description of a patient presenting with acute motor axonal neuropathy (AMAN), which is an axonal classification of Guillain-Barre Syndrome . The patient’s experience in acute care is discussed briefly, while the patients’ sub-acute and long-term rehabilitation is covered in more detail. The purpose of this case study is to highlight approaches to assessment, outcome planning, and treatment interventions in the context of a community-based rehabilitation setting during the sub-acute phase of the disease. The case study is unique as it employs an interdisciplinary approach and international classification of function, disability, and health (ICF) framework to address the pathology of the disease in a patient-specific manner.

Introduction

Acute motor axonal neuropathy (AMAN) is a variant type of Guillain-Barre Syndrome (GBS). AMAN is a non-inflammatory disease whereby axons of motor nerve cells are selectively targeted and destroyed by the body’s own immune system. The myelin sheath surrounding the axon is unaffected. Studies suggest that the body’s immune system specifically attacks the membrane surrounding the axon called the axolemma. AMAN is characterized by acute progressive motor weakness, areflexia, ataxia, oculomotor dysfunction and absence of sensory symptoms. AMAN is typically preceded by an infection from bacteria called Campylobacter jejuni or Haemophilus influenzae. Prevalence of AMAN is estimated at 5% of cases in North America and Europe, while 30-65% of cases are located in Asia, Central and South America.

While the prognosis involves two categories of patients undergoing rapid recovery or slower recovery after reaching the highest levels of unchanging symptoms and dysfunction, or plateau phase. It is proposed that recovery is achieved through mechanisms such as terminal motor nerve axonal regeneration and collateral re-innervation processes. Patients with AMAN continue to see improvements in ambulation up to four years post-diagnosis.

This brings us to the purpose of the following case study of a patient with AMAN. Physiotherapy assessment and treatment can help prevent the decline of functional status and maintain functional independence, muscle strength, posture, balance, and cardio-respiratory fitness. Moreover, it enables an individual to continue performing self-care routines and activities of daily living (ADLs). In accordance to the International Classification of Functioning, Disability and Health (ICF) framework, the primary objective of this case study is to elaborate on how physical therapy rehabilitation assessment and treatment interventions can aim to address body structure and function impairments, activity limitations, and participation restrictions in patients with AMAN. The case study further aims to focus on patient-centred care and an interdisciplinary approach to assessment and management of AMAN in a community-based rehabilitation setting.

Case Background

Trish Jones, 62 year old female, initially presented with nausea and diarrhea one week after returning home from vacation in Mexico. Due to COVID-19 travel restrictions, Trish refrained from visiting the hospital’s emergency department. Instead, Trish booked an appointment with her family doctor in two weeks’ time after her quarantine was finished. Over the next week, Trish complained of progressive muscle weakness in her hands and feet. She had difficulty grasping items with her hands and reported difficulty with climbing stairs. During the subsequent week, Trish reported decreased coordination while ambulating and unusual shortness of breath and fatigue. Prior to the visit with her family doctor, Trish lost her balance and fell while walking upstairs, which led to admission to the hospital’s emergency department.

After diagnostic investigation, Trish was diagnosed with acute motor axon neuropathy caused by Campylobacter jejuni, and was treated immediately with a high dose of intravenous immunoglobulin (IVIg) therapy. Trish spent the next two weeks in the intensive care unit (ICU), where she required mechanical ventilation due to respiratory muscle weakness. The acute health care team performed passive range of motion, splinting, airway clearance techniques, and frequent repositioning to prevent the development of contractures, deep vein thrombosis, pressure ulcers, and other complications. Prior to discharge, Trish was educated about and fitted for a 4-wheel rollator to assist in her recovery. It has been 12 weeks since she was discharged from the hospital. No other medical conditions or comorbidities have developed, and her medical status has remained stable.

The sub-acute phase of rehabilitation will be patient-specific, utilizing an ICF framework to address body function and structural impairments, activity limitations, and participation restrictions. In addition, health care providers will employ a safety-based approach to prevent patient exhaustion, and promote patient confidence in performing functional activities or tasks.

Patient Profile

Patient Profile (PP): Trish Jones, 62 year old female

Medical Diagnosis: Acute motor axonal neuropathy

Nature of the Condition: Sub-acute phase of the disease, in recovery

Primary Complaint:

• Weakness in muscles of hands, wrist, ankle, and feet,
• Fear of falling
• Decreased mobility and coordination
• Self-reported fatigue

Past Medical History (PMHx)

• Rotator Cuff Surgery 10 years ago (fully healed and no associated functional impairments)
• Campylobacter jejuni infection 12 weeks ago

Medications (Meds): High dose of intravenous immunoglobulin (IVIg) therapy as needed

Primary Reason For Referral: Recovery from AMAN

• Inability to perform certain ADLs without assistance
• Mobility levels, balance, coordination, joint range of motion, muscle strength/endurance have not returned to pre AMAN levels
• Decreased aerobic capacity contributing to feelings of fatigue
• Decreased participation in previously enjoyed leisure activities/hobbies and physical activities