Case of the Month #1: Cramping and Weakness

In four months’ time the gentleman returns to the clinic with his partner. His MRI cervical spine appeared normal but his symptoms have got worse. He developed some leg weakness and was referred to neurology.  He has had a normal CT and then MRI scan of his brain and informs you he is being investigated for Amyotrophic Lateral Sclerosis. 

What is Amyotrophic Lateral Sclerosis / Motor Neuron Disease? 

Motor Neurone Disease (MND) encompasses a group of neurodegenerative disorders affecting motor neurones in the central and peripheral nervous system, leading to progressive paralysis and eventually death¹. The annual incidence of MND is 2-4/100,000 making it relatively rare and its age of onset is typically 60-70 years². 

Amyotrophic lateral sclerosis (ALS) is the most common form of MND and is characterised by the degeneration of upper and lower motor neurones. Primary lateral sclerosis (PLS) affects only the upper motor neurones (UMN), progressive muscular atrophy (PMA) affects only the lower motor neurones (LMN) and progressive bulbar palsy (PBP) affects only the bulbar muscles². 

The main clinical feature of ALS is the combination of upper and lower motor neurone signs and symptoms.  UMN findings include weakness, stiffness, slowness, hyperreflexia and spasticity. LMN findings include weakness, atrophy, cramps and fasciculations³.  Patients with ALS may often have cognitive symptoms, including behavioural and executive dysfunction³.  Patients may often present with morning headaches¹.  

Riluzole is the only medication licenced to treat ALS in the UK and delays progression rather than providing a cure. Riluzole blocks muscular acetyl choline receptors⁴.    

How does Motor Neurone Disease Present? 

Asymmetric limb weakness is the most common presentation of ALS³.  Upper limb weakness often presents as hand weakness causing patients to drop objects or have difficulty manipulating objects with one hand (such as buttons or keys).  Lower limb weakness often presents as foot drop and a tendency to trip. Dysarthria and dysphagia are the most common bulbar symptoms¹.   

How is Motor Neurone Disease Investigated? 

There is no definitive test to diagnose MND and diagnosis is usually based around clinical history and exclusion of other diseases by neurologists.  Common investigations include²: 

• Blood Tests to exclude rheumatological conditions (elevated CK may be seen in MND). 

• Electromyography (EMG) and Nerve Conduction Studies (NCS) 

• MRI to exclude CNS pathologies (neoplasm / stroke) and nerve entrapment 

• Transcranial Magnetic Stimulation (TMS) to assess activity of Upper Motor Neurones 

• CSF Sample to assess infection / inflammation / autoimmune 

• Muscle/Nerve Tissue Biopsy  

How does MND Cause Pain? 

MND is commonly painless on presentation, however up to 85% of patients with MND experience pain and it becomes more common as the ability to move reduces⁵. This can be attributed to a variety of sources including: 

• Reduced mobility – leading to skin breakdown, musculoskeletal pain, oedema and constipation. 

• Muscle Cramps and spasticity  

• Joint pain – muscle weakness leads to increased mechanical stresses on joints 

• Comorbid conditions 

• Respiratory symptoms and interventions – such as pressure from masks 

• Neuropathic pain including paraesthesia and hyperalgesia  

How can Pain be Managed in MND?

A multidisciplinary team approach is required for MND patients6 including: 

Physiotherapy 

• Careful positioning to relieve pressure and discomfort and regular posture review 

• Passive exercise programme to ensure muscle mobility / prevent stiffness / spasm. 

• Passive massage / stretches 

• Maintenance of joint mobility 

Occupational Therapy 

• To maintain independence which can improve mental health 

• To advise on equipment to assist with mobility, manual handling, bathing and pressure care. 

Other Therapies 

• Psychological therapies to help patients cope and adjust to terminal diagnosis 

• Support groups – to offer further emotional support and practical advice 

• TENS 

• Wheel chair therapist 

• Complimentary therapies such as acupuncture and reflexology  

• Massage and heat 

Medication 

The management of pain in MND is primarily based around symptomatic management, however late in the disease palliative care approaches are often warranted⁷.