fine motor control is impaired), though no studies have shown a correlation between morphine and gross motor abilities. In terms of cognitive abilities, one study has shown that morphine may have a negative impact on anterograde and retrograde memory, but these effects are minimal and transient. Overall, it seems that acute doses of opioids in non-tolerant subjects produce minor effects in some sensory and motor abilities, and perhaps also in attention and cognition. It is likely that the effects of morphine will be more pronounced in opioid-naive subjects than chronic opioid users. In chronic opioid users, such as those on Chronic Opioid Analgesic Therapy (COAT) for managing severe, chronic pain, behavioural testing has shown normal functioning on perception, cognition, coordination and behaviour in most cases. One 2000 study analysed COAT patients to determine whether they were able to safely operate a motor vehicle. The findings from this study suggest that stable opioid use does not significantly impair abilities inherent in driving (this includes physical, cognitive and perceptual skills). COAT patients showed rapid completion of tasks that require the speed of responding for successful performance (e.g., Rey Complex Figure Test) but made more errors than controls. COAT patients showed no deficits in visual-spatial perception and organization (as shown in the WAIS-R Block Design Test) but did show impaired immediate and short-term visual memory (as shown on the Rey Complex Figure Test – Recall). These patients showed no impairments in higher-order cognitive abilities (i.e., planning).
People are also unable to actuate standard motor responses such as withdrawal from pain; as a result, testing often requires making requests of the patient such as blinking or vertical eye movement.Brain imaging may provide additional indicators of locked-in syndrome, as brain imaging provides clues as to whether or not brain function has been lost. Additionally, an EEG can allow the observation of sleep-wake patterns indicating that the patient is not unconscious but simply unable to move. Similar conditions
Amyotrophic lateral sclerosis (ALS)
Bilateral brainstem tumors
Brain death (of the whole brain or the brain stem or other part)
Coma (deep or irreversible)
Guillain–Barré syndrome
Myasthenia gravis
Poliomyelitis
Polyneuritis
Vegetative state (chronic or otherwise)

Treatment
Neither a standard treatment nor a cure is available. Stimulation of muscle reflexes with electrodes (NMES) has been known to help patients regain some muscle function. Other courses of treatment are often symptomatic. Assistive computer interface technologies such as Dasher, combined with eye tracking, may be used to help people with LIS communicate with their environment. Prognosis
It is extremely rare for any significant motor function to return, with the majority of locked-in syndrome patients never regaining motor control. However, some people with the condition continue to live for extended periods of time, while in exceptional cases, like that of Kerry Pink, Gareth Shepherd, Jacob Haendel, Kate Allatt, and Jessica Wegbrans, a near-full recovery may be achieved with intensive physical therapy. Research
New brain–computer interfaces (BCIs) may provide future remedies. One effort in 2002 allowed a fully locked-in patient to answer yes-or-no questions.