Movement disorders are a group of neurological conditions that cause abnormal
movements. They could be increased movement (like spasms, jerking or shaking)
and/or decreased or slow movement. They can affect actions you choose to make
(voluntary) or cause uncontrolled (involuntary) movements.
Every body movement you make, from lifting your leg to moving your jaw and tongue
to talk, involves complex communication between your:
      Central nervous system (your brain and spinal cord).
      Motor nerves.
      Skeletal muscles.
Damage to or malfunction of the areas of your brain that control movement results in
a movement disorder.
There are several different movement disorders, and they vary in severity. Some
only affect one area of your body, while others can affect most of your body. Some
may interfere with certain tasks, like writing, while others can lead to issues with
walking and mobility.
Abnormal movements may be the only part of a condition, such as in essential
tremor. Or they can be one of several symptoms or syndromes, like in Parkinson’s
disease (PD). In addition, certain movement disorders can be both a condition by
themselves and a symptom of other conditions, like myoclonus.
It’s important to note that conditions that result in a lack of movement (like paralysis)
or weakened muscles (such as muscular dystrophy) aren’t considered movement
disorders even though they affect mobility. Movement disorders cause abnormal,
unwanted movements.
What are the types of abnormal movements?
There are two main types of abnormal movements:
      Hyperkinetic movement.
      Hypokinetic movement.
A movement disorder can have both of these or just one.
Hyperkinetic movement
Hyperkinetic movement disorders involve increased movement. “Hyper” means
“over” or “beyond,” and “kinetic” means “motion.” It can affect voluntary movement
(actions you choose to take) or cause involuntary movement (actions that are out of
your control).
Types of hyperkinetic movement include:
      Akathisia: Akathisia makes it difficult to sit or remain still due to inner
       restlessness. Akathisia is associated with the use of certain types of
       medications, especially antipsychotic (neuroleptic) medications.
      Ataxia: Ataxia is when you have a problem with coordination, causing you to
       move in an uncertain, awkward or even clumsy way. Ataxia can be a condition
       or a symptom of another condition. It’s much more common as a symptom.
      Chorea, athetosis and ballism: Chorea is a movement disorder that causes
       involuntary, unpredictable muscle movements. The disorder can make you
       look like you’re dancing, restless or fidgety. It’s common in Huntington’s
       disease. Athetosis is a continuous stream of slow, twisting or squirming-like
       motions usually involving your hands and feet. Ballism usually involves more
       intense movements, such as forceful flinging of one arm or leg.
      Dystonia: Dystonia is sustained or intermittent muscle contractions causing
       abnormal, often repetitive movements or postures. Dystonia is a common
       symptom of cerebral palsy and several neurodegenerative conditions.
      Myoclonus: Myoclonus is brief, involuntary muscle twitching or jerking.
       People who experience myoclonic twitches or jerks have muscles that
       unexpectedly tighten (positive myoclonus) or relax (negative myoclonus).
      Spasticity: Spasticity is a disruption in muscle movement patterns that
       causes certain muscles to contract all at once when you try to move or even
       at rest. It interferes with movement and can also affect your speech and how
       you walk (gait).
      Stereotypies (stereotypic movements): Stereotypies are complex and
       usually bilateral (both sides of your body) movements. They’re patterned and
       look the same or very similar each time. Examples include rocking, hand
       flapping, pacing and body clenching. Stereotypies can be a feature of many
       conditions, including autism spectrum disorder and Rett syndrome.
      Tics: Tics are patterned, repetitive, nonrhythmic movements. Simple tics are
       brief and involve a small cluster of muscles. Examples include blinking, face
       scrunching, head jerking, throat clearing and grunting. Complex tics may last
       longer and involve more muscles. Examples include hopping and saying
       certain words or phrases. Tics are a part of Tourette’s syndrome but can be
       present in other conditions.
      Tremor: Tremor involves involuntary trembling or shaking movements. The
       movements may be in one or more parts of your body. Tremors happen when
       your muscles repeatedly contract and relax.
Hypokinetic movement
Hypokinetic movement disorders involve decreased or slow movement. “Hypo”
means “below” or “beneath.” It generally affects voluntary movement.
Parkinsonism is the main type of hypokinetic movement. It’s an umbrella term that
refers to brain conditions that cause slowed movements, rigidity (stiffness), tremor or
balance trouble.
Neurodegenerative parkinsonism most commonly happens with Parkinson’s disease,
but it can also be a feature of the following conditions:
      Multiple system atrophy.
      Corticobasal degeneration.
      Progressive supranuclear palsy.
      Lewy body dementia.
Parkinsonism can also develop due to repeated head injuries, toxic substances, use
of psychiatric medications and a lack of blood flow to certain areas of your brain.
Bradykinesia is another hypokinetic movement. It involves slowness of movement
and speed or progressive hesitations or halts as you continue movements. It’s one of
the main signs of Parkinson’s disease.
What are the types of movement disorders?
There are several movement disorders. Some include:
      Essential tremor: Essential tremor causes parts of your body to shake
       uncontrollably. It usually affects your hands and arms but can also affect your
       head, voice and other body parts.
      Huntington’s disease : Huntington’s disease is a genetic condition that
       affects your brain, causing unsteady and uncontrollable movements (chorea)
       in your hands, feet and face. Symptoms get worse over time.
      Multiple system atrophy (MSA) : MSA is a rare condition that causes certain
       brain areas to deteriorate. It may cause ataxia and parkinsonism.
      Parkinson’s disease : Parkinson’s disease is a brain disorder that causes
       unintended or uncontrollable movements and difficulty with balance and
       coordination. It also causes cognitive (mental) decline.
      Periodic limb movement disorder (PLMD) : PLMD involves repetitive limb
       movements that occur during sleep and may cause sleep disruption. The limb
       movements usually involve your lower extremities, consisting of extension of
       your big toe and flexion of your ankle, knee and hip.
      Progressive supranuclear palsy (PSP) : PSP is a rare neurodegenerative
       disorder that damages certain areas of your brain. It affects how you walk,
       think, swallow and move your eyes.
      Restless leg syndrome (RLS) : RLS is a sleep disorder that causes an
       intense, often irresistible urge to move your legs (and even your arms or
       body). It occurs along with other sensations in your limbs like pulling,
       creeping, tugging, throbbing, itching, aching, burning or crawling.
      Rett syndrome: Rett syndrome is a rare genetic condition that affects
       speech, purposeful hand use and coordination.
      Tardive dyskinesia: Tardive dyskinesia can result from taking antipsychotic
       (neuroleptic) medications for many years. It can cause involuntary facial tics.
       It can also cause uncontrollable movements like lip-smacking.
      Tourette syndrome: Tourette syndrome is a neurological disorder that affects
       your brain and nerves. It causes you to make sudden movements or sounds
       (tics) and is accompanied by anxiety, ADHD and often obsessive-compulsive
       disorder.
      Wilson disease: Wilson disease is a rare genetic condition that happens
       when your body accumulates too much copper, especially in your liver and
       brain. It can cause stiff muscles, tremors and uncontrolled movements.
What is the most common movement disorder?
The two most common movement disorders are Parkinson’s disease and essential
tremor.
Symptoms and Causes
What are the symptoms of movement disorders?
The symptoms of movement disorders vary widely. All movement disorders cause
abnormal movements. Some movement disorders have other symptoms, such as
thinking and mood changes. The symptoms can range in severity from barely
noticeable to disruptive.
In general, signs and symptoms of movement disorders include:
      Episodes of uncontrolled movement, like twitches, spasms, tremors, jerks,
       twisting and shaking.
      Problems with coordination and balance.
      Trouble with certain movement tasks, such as writing, swallowing or speaking.
      Difficulty walking or changes to your gait.
      Stiffness or rigidity of your limbs and trunk.
Abnormal movements can affect one or more of several parts of your body, including
your:
      Limbs.
      Hands and fingers.
      Feet and toes.
      Facial muscles.
      Head and neck.
      Trunk and posture.
      Voice.