Essential Myoclonus: This condition is characterized by sudden, brief, shock-like jerks of a muscle or a group of muscles, often involving the arms and legs. It is usually benign and can be inherited. The intermittent nature of the jerky movements fits well with essential myoclonus, making it a strong candidate for the single most likely diagnosis.

Tardive Dyskinesia: This is a side effect of long-term use of neuroleptic drugs, characterized by repetitive, involuntary, purposeless movements. While it more commonly affects the face, it can also involve the limbs, presenting as jerky movements.
Anxiety or Stress-induced Movement Disorder: Stress and anxiety can sometimes manifest as movement disorders, including intermittent jerky movements of the arms and legs. This is often seen in individuals with a history of anxiety disorders.
Huntington's Disease: An inherited disorder that causes progressive damage to the brain, leading to cognitive, motor, and psychiatric disturbances. Early signs can include subtle movement disturbances, such as jerky movements.

Creutzfeldt-Jakob Disease: A rare, degenerative, fatal brain disorder that can cause a variety of neurological symptoms, including myoclonus (sudden, involuntary jerks). Given its fatal nature and the importance of early diagnosis for potential treatment and isolation, it's crucial not to miss this diagnosis.
Subacute Sclerosing Panencephalitis (SSPE): A rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection with the measles virus. It can present with myoclonus among other neurological symptoms.
Wilson's Disease: An inherited disorder that causes too much copper to accumulate in the body, particularly in the liver, brain, and other vital organs. Neurological symptoms can include tremors and involuntary movements.

Dopa-Responsive Dystonia: A rare genetic disorder characterized by progressive dystonia (involuntary muscle contractions) that typically starts in childhood. While it primarily affects the legs, it can also involve other parts of the body and may present with jerky movements.
Neurodegeneration with Brain Iron Accumulation (NBIA): A group of rare, inherited disorders characterized by progressive neurological deterioration and excessive iron accumulation in the brain. Some forms can present with dystonia and involuntary movements.
Mitochondrial Myopathies: A group of disorders caused by mutations in the mitochondria, which affect muscle and nerve cells. Some types can present with myoclonus and other movement disorders.