It is also found in MERRF (Myoclonic Epilepsy with Ragged Red Fibers), a rare mitochondrial encephalomyopathy. Jerks of muscle groups, much of the body, or a series in rapid succession, which results in the person jerking bolt upright from a more relaxed sitting position is sometimes seen in ambulatory patients being treated with high doses of morphine, hydromorphone, and similar drugs, and is possibly a sign of high and/or rapidly increasing serum levels of these drugs. Myoclonic jerks caused by other opioids, such as tramadol and pethidine, may be less benign. Medications unrelated to opioids, such as anticholinergics, are known to cause myoclonic jerks. Pathophysiology
Most myoclonus is caused by a disturbance of the central nervous system. Some are from peripheral nervous system injury. Studies suggest several locations in the brain are involved in myoclonus. One is in the brainstem, close to structures that are responsible for the startle response, an automatic reaction to an unexpected stimulus involving rapid muscle contraction. The specific mechanisms underlying myoclonus are not yet fully understood. Scientists believe that some types of stimulus-sensitive myoclonus may involve overexcitability of the parts of the brain that control movement. These parts are interconnected in a series of feedback loops called motor pathways. These pathways facilitate and modulate communication between the brain and muscles. Key elements of this communication are chemicals known as neurotransmitters, which carry messages from one nerve cell, or neuron, to another. Neurotransmitters are released by neurons and attach themselves to receptors on parts of neighboring cells.
The walk disturbance (where a person is so worried about how they walk that they may lose balance) may appear, especially when passing a group of people. Blushing is commonly exhibited by individuals with social phobia. These visible symptoms further reinforce the anxiety in the presence of others. A 2006 study found that the area of the brain called the amygdala, part of the limbic system, is hyperactive when patients are shown threatening faces or confronted with frightening situations. They found that patients with more severe social phobia showed a correlation with increased response in their amygdalae. People with SAD may avoid looking at other people, and even their surroundings, to a greater extent than their peers, possibly to decrease the risk of eye contact, which can be interpreted as a nonverbal signal of openness to social interaction. Social aspects
People with SAD avoid situations that most people consider "normal". They may have a hard time understanding how others can handle these situations so easily. People with SAD avoid all or most social situations and hide from others, which can affect their personal relationships. Social phobia can completely remove people from social situations due to the irrational fear of these situations. People with SAD may be addicted to social media networks, have sleep deprivation, and feel good when they avoid human interactions. SAD can also lead to low self-esteem, negative thoughts, major depressive disorder, sensitivity to criticism, and poor social skills that dont improve.