Amputation is the removal of a limb by trauma, medical illness, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventive surgery for such problems. A special case is that of congenital amputation, a congenital disorder, where fetal limbs have been cut off by constrictive bands. In some countries, judicial amputation is currently used to punish people who commit crimes. Amputation has also been used as a tactic in war and acts of terrorism; it may also occur as a war injury. In some cultures and religions, minor amputations or mutilations are considered a ritual accomplishment. When done by a person, the person executing the amputation is an amputator. The oldest evidence of this practice comes from a skeleton found buried in Liang Tebo cave, East Kalimantan, Indonesian Borneo dating back to at least 31,000 years ago, where it was done when the amputee was a young child.
In physiology, nociception, also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response.
In medicine, a prosthesis, or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through physical trauma, disease, or a condition present at birth. Prostheses are intended to restore the normal functions of the missing body part. A person who has undergone an amputation is sometimes referred to as an amputee, however, this term may be offensive. Rehabilitation for someone with an amputation is primarily coordinated by a physiatrist as part of an inter-disciplinary team consisting of physiatrists, prosthetists, nurses, physical therapists, and occupational therapists. Prostheses can be created by hand or with computer-aided design (CAD), a software interface that helps creators design and analyze the creation with computer-generated 2-D and 3-D graphics as well as analysis and optimization tools.
A phantom limb is the sensation that an amputated or missing limb is still attached. It is a chronic condition which is often resistant to treatment. When the cut ends of sensory fibres are stimulated during thigh movements, the patient feels as if the sensation is arising from the non-existent limb. Sometimes the patient might feel pain in the non-existent limb. Approximately 80–100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience painful phantom limb sensation. These sensations are relatively common in amputees and usually resolve within two to three years without treatment. Research continues to explore the underlying mechanisms of phantom limb pain (PLP) and effective treatment options.
Vilayanur Subramanian Ramachandran is an Indian-American neuroscientist. He is known for his wide-ranging experiments and theories in behavioral neurology, including the invention of the mirror box. Ramachandran is a distinguished professor in UCSD's Department of Psychology, where he is the director of the Center for Brain and Cognition.
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded receptor potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal root ganglia of the spinal cord.
Mirror therapy (MT) or mirror visual feedback (MVF) is a therapy for pain or disability that affects one side of the patient more than the other side. It was invented by Vilayanur S. Ramachandran to treat post-amputation patients who had phantom limb pain (PLP). Ramachandran created a visual illusion of two intact limbs by putting the patient's affected limb into a "mirror box," with a mirror down the center.
Phantom pain is a painful perception that an individual experiences relating to a limb or an organ that is not physically part of the body, either because it was removed or was never there in the first place.
Neuroprosthetics is a discipline related to neuroscience and biomedical engineering concerned with developing neural prostheses. They are sometimes contrasted with a brain–computer interface, which connects the brain to a computer rather than a device meant to replace missing biological functionality.
Phantom eye syndrome (PES) is a phantom pain in the eye and visual hallucinations after the removal of an eye.
Targeted reinnervation enables amputees to control motorized prosthetic devices and regain sensory feedback. The method was developed by Dr. Todd Kuiken at Northwestern University and Rehabilitation Institute of Chicago and Dr. Gregory Dumanian at Northwestern University Division of Plastic Surgery.
Body schema is an organism's internal model of its own body, including the position of its limbs. The neurologist Sir Henry Head originally defined it as a postural model of the body that actively organizes and modifies 'the impressions produced by incoming sensory impulses in such a way that the final sensation of body position, or of locality, rises into consciousness charged with a relation to something that has happened before'. As a postural model that keeps track of limb position, it plays an important role in control of action.
Proprioception is the sense of self-movement, force, and body position.
Stump socks are tubular medical or clothing accessories with a blind end that are fashioned similar to socks, usually without a heel. They are worn on amputation stumps for a number of reasons. As stump socks are typically worn on body parts that do not contain a foot, their definition is distinct from the average sock type garment.
Spinal locomotion results from intricate dynamic interactions between a central program in lower thoracolumbar spine and proprioceptive feedback from body in the absence of central control by brain as in complete spinal cord injury (SCI). Following SCI, the spinal circuitry below the lesion site does not become silent; rather, it continues to maintain active and functional neuronal properties, although in a modified manner.
During every moment of an organism's life, sensory information is being taken in by sensory receptors and processed by the nervous system. Sensory information is stored in sensory memory just long enough to be transferred to short-term memory. Humans have five traditional senses: sight, hearing, taste, smell, touch. Sensory memory (SM) allows individuals to retain impressions of sensory information after the original stimulus has ceased. A common demonstration of SM is a child's ability to write letters and make circles by twirling a sparkler at night. When the sparkler is spun fast enough, it appears to leave a trail which forms a continuous image. This "light trail" is the image that is represented in the visual sensory store known as iconic memory. The other two types of SM that have been most extensively studied are echoic memory, and haptic memory; however, it is reasonable to assume that each physiological sense has a corresponding memory store. For example, children have been shown to remember specific "sweet" tastes during incidental learning trials but the nature of this gustatory store is still unclear. However, sensory memories might be related to a region of the thalamus, which serves as a source of signals encoding past experiences in the neocortex.
A cortical implant is a subset of neuroprosthetics that is in direct connection with the cerebral cortex of the brain. By directly interfacing with different regions of the cortex, the cortical implant can provide stimulation to an immediate area and provide different benefits, depending on its design and placement. A typical cortical implant is an implantable microelectrode array, which is a small device through which a neural signal can be received or transmitted.
Gait deviations are nominally referred to as any variation of standard human gait, typically manifesting as a coping mechanism in response to an anatomical impairment. Lower-limb amputees are unable to maintain the characteristic walking patterns of an able-bodied individual due to the removal of some portion of the impaired leg. Without the anatomical structure and neuromechanical control of the removed leg segment, amputees must use alternative compensatory strategies to walk efficiently. Prosthetic limbs provide support to the user and more advanced models attempt to mimic the function of the missing anatomy, including biomechanically controlled ankle and knee joints. However, amputees still display quantifiable differences in many measures of ambulation when compared to able-bodied individuals. Several common observations are whole-body movements, slower and wider steps, shorter strides, and increased sway.
Proprioception refers to the sensory information relayed from muscles, tendons, and skin that allows for the perception of the body in space. This feedback allows for more fine control of movement. In the brain, proprioceptive integration occurs in the somatosensory cortex, and motor commands are generated in the motor cortex. In the spinal cord, sensory and motor signals are integrated and modulated by motor neuron pools called central pattern generators (CPGs). At the base level, sensory input is relayed by muscle spindles in the muscle and Golgi tendon organs (GTOs) in tendons, alongside cutaneous sensors in the skin.
Limb telescoping is the progressive shortening of a phantom limb as the cortical regions are reorganized following an amputation. During this reorganization, proximal portions of the residual limb are perceived as more distal parts of the phantom limb. Such effect is responsible for increased phantom pain due to the discrepancy between the patient’s body perception and their actual body. This effect may last from weeks up to years after post-amputation.
