Isaacs Mertens Syndrome, also known as Isaacs syndrome or neuromyotonia, is a rare neurological disorder characterized by muscle stiffness, continuous muscle activity, and spontaneous muscle contractions or twitching. This disorder is named after Isaac Edward Mertens, a British neurologist who first described it in the late 1950s.
Individuals with Isaacs Mertens Syndrome often experience muscle stiffness or cramps that typically occur in the limbs, face, or tongue. These symptoms result from the excessive and involuntary firing of the muscles' peripheral nerves, leading to continuous muscle contractions. Muscle twitching or rippling movements may also be observed. These symptoms are frequently noticeable during rest and become more pronounced with physical activity or stress.
Other common features associated with Isaacs Mertens Syndrome include muscle stiffness or myotonia immediately after muscle contraction, delayed muscle relaxation after the contractions, and reduced or absent reflexes. Some individuals with this syndrome may also develop muscle weakness over time.
The underlying cause of Isaacs Mertens Syndrome is often associated with autoimmune disorders, such as neuromyotonia associated with Morvan syndrome, or certain genetic mutations. Diagnosis is typically made based on the presence of characteristic clinical symptoms and supported by various specialized tests, including electromyography (EMG), nerve conduction studies, and genetic testing.
Management of Isaacs Mertens Syndrome aims to alleviate symptoms and improve the overall quality of life for patients. Treatment options may include medications to suppress muscle activity, such as anticonvulsant drugs, immunosuppressants, or plasma exchange in cases of autoimmune-related syndromes. Physical therapy and other supportive measures may also be recommended to address muscle stiffness and weakness while enhancing mobility and function.
