What Is Dejerine-Sottas Syndrome

Dejerine-Sottas Syndrome (DSS) is a rare neurological condition that causes the weakening of muscles in the limbs due to damage to the nerves. DSS is characterised by moderate to severe weakness and loss of sensation in the arms and legs. The condition is genetic and caused by a mutation in the PMP22 gene.

Overview

Dejerine-Sottas Syndrome is a rare genetic condition that affects the peripheral nervous system. This type of condition is often referred to as peripheral neuropathy or just neuropathy for short. Peripheral nerves exist outside the brain and spinal cord, and they transmit impulses to the muscles causing them to contract, resulting in movement. DSS is characterised by a gradual weakening of muscles in the limbs, particularly the fingers, hands, toes and feet (the distal extremities). DSS primarily affects both motor (movement) and sensory (feeling and touch) nerves. Damage to the nerves causes progressive muscle wasting and sensory loss.

DSS is a type of Charcot-Marie-Tooth Disease and is caused by mutations in genes such as the PMP22, MPZ, and EGR2 genes.¹ DSS is one of the demyelinating Charcot-Marie-Tooth Disease cases that present early, often existing from birth or infancy.² In DSS, genetic mutations mess with a protective insulation layer around the nerves called myelin. When these genes undergo mutations, it disrupts the production of myelin, leaving nerves vulnerable and causing the symptoms observed in DSS. This myelin layer helps nerve signals travel swiftly and accurately between your brain and the rest of your body. 

Clinical presentation

The onset of DSS is usually in infancy, between 1 and 2 years old, and is described as progressive weakness of the upper and lower extremities (arms and legs), as well as loss of sensation, deformed feet and difficulty in walking.⁴ Less common symptoms include hearing loss and nystagmus (involuntary movement of the eye). DSS will affect people in different ways, the most characteristic symptoms include:

• Pain
• Altered sensations
• Muscle weakness and atrophy
• Delay of physical milestones in infancy
• Inability to walk
• Lack of coordination of movement and balance, known as ataxia
• Hand and foot deformities
• Scoliosis
• Contractures
• Muscle cramps
• Hearing loss

Diagnosis

Manifestation of the disease at a young age and a positive familial history should give rise to the suspicion of a hereditary nerve disorder. Early diagnosis and appropriate interventions can significantly influence the course of the condition. Diagnosis of DSS requires a combination of clinical evaluation, specialised tests, and genetic investigations.³ Criteria for a clinical diagnosis include:

1. Symptoms began by age two with delayed motor milestones
2. Severe motor and sensory impact
3. The speed of motor nerve conduction (muscle response) is reduced.
4. Nerve biopsy shows loss of myelin

A detailed medical history and a physical examination are the first steps in evaluation.

Clinical evaluation by a neurologist or specialist typically looks for signs like muscle weakness, abnormal reflexes, and sensory issues.

Electrophysiological tests, such as nerve conduction studies and electromyography (EMG), are used to measure the electrical activity in nerves and muscles. In DSS, these tests often show slow nerve conduction and irregular electrical patterns.

Genetic testing is essential to confirm the diagnosis and pinpoint the specific genetic mutations causing DSS. This step helps not only with diagnosis but also with understanding the inheritance pattern, which is crucial for genetic counselling within families.

Treatment and management 

Currently, there is no known cure. However, early diagnosis and appropriate interventions can significantly improve the lives of individuals with DSS. Ongoing research offers hope for better treatments and outcomes in the future. 

Medications

While medications cannot cure Dejerine-Sottas Syndrome, they can help manage specific symptoms. Pain medications can be used to alleviate discomfort and muscle spasms. Chronic pain is a common challenge in DSS, and these medications offer some much-needed relief. Muscle pain can be treated with painkillers such as paracetamol or nonsteroidal anti-inflammatory medications. Nerve pain can be reduced using a form of antidepressant called tricyclic antidepressants or other medications such as carbamazepine or gabapentin. Muscle relaxants can help with muscle stiffness and spasms. They aim to improve mobility and reduce discomfort.

Physiotherapy treatment

Physiotherapy is one of the most important treatment methods for relieving the symptoms and slowing the progression of Dejerine-Sottas Syndrome. A physiotherapist will conduct a thorough assessment and devise an individual treatment plan aimed at helping maintain as much movement and functional independence as possible. Physiotherapy treatment for Dejerine-Sottas Syndrome often focuses on improving sitting and standing balance to assist in walking as well as treating any changes in muscle tone by encouraging the active movement of the affected limbs. Physiotherapy also includes exercises to increase the strength of the muscles in the affected limbs, which helps increase muscle control. Stretching exercises help maintain and improve the normal range of joint movement and reduce muscle stiffness. Physiotherapists can advise on the use of walking aids to assist with walking difficulty. The use of a walking aid can reduce accidents such as falls and help increase functional independence and safety.

Occupational therapy

Occupational therapists focus on daily living skills. They help individuals find new ways to perform tasks like dressing, eating, and grooming, which may become challenging due to muscle weakness or sensory disturbances.

Orthopaedic interventions

Over time, Dejerine-Sottas Syndrome can lead to skeletal deformities. Orthopaedic surgeons may be involved in addressing these issues, which can include procedures to correct joint or bone abnormalities.

Conclusion

Dejerine-Sottas Syndrome can be defined as a rare genetic motor and sensory nerve disorder. It often leads to progressive muscle weakness, sensory loss, and other neurological impairments. The effects of the disease are caused by damage to the protective insulation around the nerves, leading to impairment in nerve impulse conduction. Genetic testing and nerve conduction studies are often necessary for a definitive diagnosis. There is no cure, so management of the disease focuses on alleviating symptoms and improving the quality of life. This may include physical therapy, orthopaedic interventions, and medications to relieve pain and discomfort. Dejerine-Sottas Syndrome remains a challenging and rare neurological disorder, but ongoing research in genetics and neurology offers hope for better understanding and potential treatments. Early diagnosis and a multidisciplinary approach to care are essential in helping individuals and improving their quality of life.