Studies have shown that exposure to rotational motions in a virtual environment can cause significant increases in nausea and other symptoms of motion sickness.In a study conducted by the U.S. Army Research Institute for the Behavioral and Social Sciences in a report published May 1995 titled "Technical Report 1027 – Simulator Sickness in Virtual Environments", out of 742 pilot exposures from 11 military flight simulators, "approximately half of the pilots (334) reported post-effects of some kind: 250 (34%) reported that symptoms dissipated in less than one hour, 44 (6%) reported that symptoms lasted longer than four hours, and 28 (4%) reported that symptoms lasted longer than six hours. There were also four (1%) reported cases of spontaneously occurring flashbacks." Motion that is seen and felt
When moving within a rotating reference frame such as in a centrifuge or environment where gravity is simulated with centrifugal force, the coriolis effect causes a sense of motion in the vestibular system that does not match the motion that is seen. Pathophysiology
There are various hypotheses that attempt to explain the cause of the condition. Sensory conflict theory
Contemporary sensory conflict theory, referring to "a discontinuity between either visual, proprioceptive, and somatosensory input, or semicircular canal and otolith input", is probably the most thoroughly studied. According to this theory, when the brain presents the mind with two incongruous states of motion; the result is often nausea and other symptoms of disorientation known as motion sickness.
There is a risk of premature death in affected individuals due to deep vein thrombosis and pulmonary embolism caused by the vessel malformations that are associated with this disorder. Because of carrying excess weight and enlarged limbs, arthritis and muscle pain may also be symptoms. Further risks may occur due to the mass of extra tissue.The disorder itself does not uniformly cause learning impairments: the distribution of intelligence deficits among those with Proteus syndrome appears higher than that of the general population, although this is difficult to determine with statistical significance. In addition, the presence of visible deformity may have a negative effect on the social experiences of the affected individual, causing cognitive and social deficits.Affected individuals are at increased risk for developing certain tumors including unilateral ovarian cystadenomas, testicular tumors, meningiomas, and monomorphic adenomas of the parotid gland.Hemimegalencephaly is often found to be associated. Orthopaedic features
The musculoskeletal manifestations of Proteus syndrome are frequent and recognizable. Patients tend to demonstrate a unique pattern of skeletal abnormalities. The orthopaedic features are usually bilateral, asymmetrical, progressive and involving all four limbs and spine. Affected patients usually have localized periarticular limb distortions, limb length discrepancy, and spine deformity. Patients with Proteus syndrome can have regular bone configuration and contours despite the bone enlargement. Patients can also exhibit deformation of the skull in the form of dolichocephaly or elongated skull and facial abnormalities. Because of the rarity of the syndrome and the variability of signs, the orthopaedic management should be individualized. Genetics
In 2011 researchers determined the cause of Proteus syndrome.