Hereditary sensory motor neuropathy (HSMN)

Hereditary sensory motor neuropathy (HSMN) is a group of genetic disorders affecting the peripheral nervous system, characterized by the progressive degeneration of motor and sensory nerves.

This group of disorders includes genetic conditions such as Charcot-Marie-Tooth disease and peroneal muscular atrophy . Both disorders cause challenges for individuals that impact their daily life.

Aurora Health Care’s team of expert neurologists will help you understand the complexities of hereditary motor sensory neuropathy and create a personalized treatment plan to help you live with this condition and improve your quality of life.

What is hereditary motor sensory neuropathy?

HSMN refers to a group of inherited neurological disorders characterized by progressive damage to the peripheral nerves. There are stark differences between HSNM and peripheral neuropathy despite both conditions impacting the same nerves.

HSMN is primarily caused by genetic mutations that affect the structure or function of proteins involved in the function and maintenance of the peripheral nervous system.

The peripheral nerves are responsible for transmitting signals between the brain, spinal cord and the body's muscles and sensory organs. If you have HSMN, these nerves become unresponsive over time and cause symptoms such as muscle weakness, decreased sensation and abnormal reflexes.

The severity and specific symptoms can be different for everyone, even within families where this condition is prevalent.

Hereditary motor sensory neuropathy symptoms

Hereditary motor sensory neuropathy has a range of symptoms that affect both sensory and motor functions.

HSMN symptoms can vary in severity and presentation but generally include disturbances in sensation and movement.

Sensory symptoms

Sensory symptoms of HSMN often involve changes to feeling and perception. If you have HSMN, you may experience:

• Numbness
• Tingling sensations
• Reduced ability to feel pain or temperature changes

Sensory symptoms can affect various parts of the body, including the hands, feet and limbs.

Motor symptoms

Motor symptoms of HSMN typically manifest as weakness, muscle wasting and difficulties with coordination and balance.

Affected individuals may have trouble walking, running or performing tasks that require fine motor skills. Muscle weakness can progress over time and may lead to significant impairments in mobility.

It is important to understand that symptoms may present themselves very differently in each person with HSMN. While certain symptoms may be common, such as sensory abnormalities and muscle weakness, the severity and specific manifestations can vary widely.

Diagnosis of hereditary motor sensory neuropathy

Diagnosing HSMN involves a combination of a physical exam, review of your medical history and symptoms, and neurological tests and digital imaging.

Your provider will begin by taking a detailed medical history, including symptoms experienced and any family history of neurological and genetic disorders. During your physical exam, your provider will perform a neurological exam to assess muscle strength, sensation, reflexes and coordination.

Your provider may recommend nerve function and imaging tests to identify the type, location and extent of any nerve damage. In rare cases, a nerve biopsy may be recommended to examine a small sample of nerve tissue under a microscope.

Imaging tests

• CT scan: CT scans of the spine can show herniated discs, spinal stenosis (narrowing of the spinal canal), tumors and bone irregularities that may affect nerves.
• MRI: An MRI of the spine can reveal tumors or nerve root compression, also known as a pinched nerve, that could be causing HSMN.

Nerve function tests

• Nerve conduction studies (NCS): NCS are commonly used to assess the function of peripheral nerves. This test involves applying small electrical shocks to nerves and recording the speed and strength of the nerve signals. Abnormalities in nerve conduction can indicate nerve damage, characteristic of HSMN.
• Electromyography (EMG): An electromyography test evaluates the electrical activity of muscles. It can help differentiate between muscle disorders and nerve disorders by detecting abnormalities in muscle response to nerve stimulation.

Genetic testing

Genetic testing can confirm the presence of specific gene mutations associated with HSMN, such as mutations in genes related to Charcot-Marie-Tooth disease or peroneal muscular atrophy. Genetic testing may involve taking blood samples or other tissue samples to identify mutations.

Treatment for hereditary motor sensory neuropathy

Treatment for HMSN focuses on managing symptoms, improving function and enhancing quality of life. While there is no cure for HMSN, various interventions and therapies can help alleviate symptoms and slow disease progression.

Some common HMSN treatment options include:

• Physical therapy: Physical therapy plays a crucial role in managing HMSN by improving muscle strength, flexibility and coordination.
• Occupational therapy: Occupational therapy focuses on maximizing independence and function in daily activities.
• Using orthotic devices: Orthotic devices such as braces and splints can provide support and stability, helping to improve gait and function.
• Pain management: Pain management strategies may include over-the-counter pain medications such as ibuprofen or naproxen or prescription medications such as antidepressants or anti-seizure medications.
• Mobility aids: Assistive devices such as canes, walkers or wheelchairs may be necessary for individuals with significant mobility impairments.

Your care team will work together to address symptoms comprehensively and focus on individualized care.

Living with hereditary sensory motor neuropathy

Living with HSMN presents unique challenges, but with proper management and support, you can lead a fulfilling life.

While HSMN is a progressive condition, the long-term outlook varies depending on the specific type of HSMN you have and individual factors. Some individuals may experience mild symptoms that remain stable over time, while others may face more significant challenges with mobility and function.

Early intervention is crucial in managing HSMN effectively. A multidisciplinary approach involving various providers, including neurologists, physical therapists, occupational therapists and mental health specialists, can address your individual needs.