Neurobiology
Hypokinetic symptoms arise from damage to the basal ganglia, which plays a role in producing force and computing the effort necessary to make a movement. Two possible neural pathways enable the basal ganglia to produce movement. When activated, the direct pathway sends sensory and motor information from the cerebral cortex to the first structure of the basal ganglia, the putamen. That information directly inhibits the globus pallidus internal and allows free movement. The indirect pathway, traveling through the putamen, globus pallidus external, and subthalamic nucleus, activates the globus pallidus internal threshold and inhibits the thalamus from communicating with the motor cortex, producing hypokinetic symptoms. When levels of dopamine decrease, the normal wave-firing pattern of basal ganglia neural oscillations changes and the tendency for oscillations increases, particularly in the beta wave of the basal ganglia. Recent research indicates, when oscillations fire simultaneously, processing is disrupted at the thalamus and cortex, affecting activities such as motor planning and sequence learning, as well as causing hypokinetic tremors. Treatments
Dopaminergic drugs
Dopaminergic drugs are commonly used in the early stages of the hypokinesia to treat patients. With increased intake, though, they can become ineffective because of the development of noradrenergic lesions. While initially the dopaminergic drugs may be effective, these noradrenergic lesions are associated with hypokinesic gait disorder development later on.Some Parkinsons patients are unable to move during sleep, prompting the diagnosis of "nocturnal hypokinesia". Physicians have experienced success treating this sleep disorder with slow-release or night-time dopaminergic drugs, and in some cases, continuous stimulation by the dopamine agonist rotigotine.
The phenomenon can occur over water, when cold arctic air passes over relatively warm water. Intensity and damage
The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. The Enhanced Fujita (EF) Scale was an update to the older Fujita scale, by expert elicitation, using engineered wind estimates and better damage descriptions. The EF Scale was designed so that a tornado rated on the Fujita scale would receive the same numerical rating, and was implemented starting in the United States in 2007. An EF0 tornado will probably damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler weather radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating. Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track tornadoes tend to be stronger. In the case of violent tornadoes, only a small portion of the path is of violent intensity, most of the higher intensity from subvortices.In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes. The rate of occurrence drops off quickly with increasing strength—less than 1% are violent tornadoes (EF4, T8 or stronger).