Phantom Limbs Essay

p.483 The cell bodies of primary-order neurons or pain-transmitting neurons reside in the dorsal root ganglia just lateral to the spine along the sensory pathways that penetrate the posterior part of the cord. The second order neurons are found in the dorsal horn (p.484) Most nociceptive information tranvels by means of ascending columns in the lateral spinothalamic tract (also called the anterolateral funiculus). The principal target for nociceptive afferents is the thalamus (the major relay station of sensory information in general) Third order neurons project to portions of the CNS involved in the processing and interpretation of pain, the chief areas being the reticular and limbic systems and cerebral cortex. (p 484)

When a body part is lost the corresponding part of the brain is not able to handle the loss and rewires its circuitry to make up for the signals it was no longer receiving from the missing digit. The rewiring might occur in one of two ways. Perhaps nerve impulses in the sensory cortex begin to course down previously untraveled pathways. The second theory is that neighboring neurons in the cortex may actually invade the territory left fallow because sensations are no longer received from the missing limb.

Kathy, a 20-year-old woman, awakens one morning to a tingling, numb sensation covering both of her feet. This has happened to her a number of times throughout the year. In the past, when experiencing this sensation, within a couple of days to a week the numbness would subside, and so she is not too concerned. About a week later, she

These receptors record on a extensive form of sensory modalities including changes in temperature, stress, touch, sound, mild, style, odor, physique and limb actions, and even blood pressure and chemistry. Scientists have recognized for nearly a hundred thirty years that distinct afferent nerve fibers of the peripheral nervous procedure are in contact with specialized non neural receptive buildings which realize and transmit sensory knowledge from the periphery to the Central Nervous System. The non neural receptive structure in conjunction with its afferent nerve fiber is mainly called a

The phantom limb pain the woman is experiencing is described as a painful condition of the amputated limb after the stump has completely healed. It is a chronic pain that occurs in more than 80% of amputees especially those who suffered pain in the limb before the amputation. Theories suggest that phantom limb pain results from redevelopment or hyperactivity of cut peripheral nerves, scar tissue or neuroma formation in the cut peripheral nerves, spinal cord deafferentation, and alterations in the thalamus and cortex. More so, the CNS integration, which involves reorganization and plastic modifications of the somatosensory cortex, effects the receptors in perceiving the pain of the amputated limb despite of the limb itself being absent. In addition,

Also, many drugs have been used post surgery in treating PLP with success, particularly oral morphine. An inexpensive and easy drug-free therapy to follow, which its’ success in reducing PLP has been replicated in many studies, is mirror therapy. Mirror therapy also has the added benefit of being able to be done at home by the patient at his or her own pace. Finally, there are many novel therapies that have been very promising in treating PLP including cryoablation therapy of the affected nerve and/or neuroma, and EMDR therapy, which can simultaneously treat PTSD and similar

Even if an individual does not experience any obvious structural changes, alterations in cerebral blood flow, neuronal activity, and neurotransmitters can still be apparent.1

The earliest hypothesis regarding the cause of phantom limbs and pain was that of neuromas. These were thought to be nodules comprised of remaining nerves located at the end of the stump. These neuromas presumably continued to generate impulses that traveled up the spinal cord to portions of the thalamus and somatosensory domains of the cortex. As a result, treatment involved cutting the nerves just above the neuroma in an attempt to interrupt signaling at each somatosensory level (5). This and other related theories were deemed unsatisfactory because of the fact the phantom pain always returned, indicating that there was a more complex reason.

Chapter three, The Disembodied Lady, tells the story of a women named Christina who loses her entire sense of proprioception, otherwise known as “sixth sense”. At the age of twenty-seven, she was hospitalized to have her gallbladder removed. The day before her surgery, Christina had a nightmare that she could not stop her body from flailing about and hardly felt anything. Later the next day, all the symptoms came true from her dream. She said that she couldn’t feel her body and even feeling disembodied from it. Oliver Sacks examined Christina and found that she lost all proprioception and was diagnosed with polyneuritis. She had no sense of familiarity with her body, though could feel superficial sensations like wind on her body. To compensate, she’d used her senses to regain a sense of her body like using her vision to control how she moves and hearing to vocalize her tone and volume. She had to relearn basic behaviors, making her question her question her sense of connection to her own body. Even after years of working around proprioception, she still felt disembodied from her own body. In the Postscript, Sacks mentions other patient who lost their proprioception due to taking large amounts of vitamin B6.

The CNS contains the brain and spinal cord. Its main functions include: processing, integrating, and coordinating sensory information and motor instructions. The sensory data conducts information that is being processed from internal and external conditions the body is experiencing. Motor commands regulate and control peripheral organs (skeletal muscles). The brain functions under memory, emotions, learning, and intelligence. The PNS consist of the neural tissue found outside of the CNS. It functions in sending data to the CNS which motor commands are than carried out to the peripheral tissues/systems. Multiple nerve fibers send sensory data and motor commands in the PNS. The nerves that assist with transmitting data include the cranial nerves and spinal nerve. However, the PNS can be divided into afferent (to bring in) and efferent (to bring out) divisions of transferring data. The afferent division functions in bringing in sensory data to the CNS. Sensory structures are receptors that detect internal/external environmental change and adjusting accordingly. The efferent division functions in carrying out motor commands from the CNS to glands, muscles, and adipose tissue. The efferent division contains somatic

Sacks discussed the ideas behind the phantom limb and how they affected many peoples live. The most interesting story was about a sailor that accidentally cut off his index finger. For forty years he thought he would poke himself in the eye whenever he moved his hand to his face. One day he lost the feeling in his entire hand including his phantom finger and his problem was cured (Sacks 66-67). Up to 70 percent of amputees confirmed that they still feel or still thought a missing limb was there. They often feel that they can reach out and grab something. Some won't sleep in a certain way because they feel the missing limb between them and the mattress. The sensations felt stem from the activity of the sensory axons

An extensive matrix of neurons in the brain gives us the sense of our own bodies and body parts. Pain results when this matrix produces an abnormal pattern of activity, as a result of memories, emotions, expectations or signals from various brain centres and not just from signals from peripheral nerves. Because of the lack of sensory stimulation or a person’s efforts to move a nonexistent limb, abnormal patterns may arise, resulting in phantom pain.

The human skeleton has 6 main functions that provide the body with good health. They are as follows:

Phantom limb pain is a painful sensation experienced in a body part which is no longer part of the body, often due to amputation.(3) Individuals also reported that tingling as well as various types of pain have occurred, and these sensations may eventually disappear or may persist as cramping, shooting, burning or crushing

The neurons in the brain tissue communicate with each other via electrical signals, generating measurable action potential activity. Electrophysiological techniques have been developed to measure this electrical activity. Electrophysiological techniques are some of the classic methods of brain research, partly because they are very sensitive and accurate. They provide quite a number of insights into the subject’s mind as well as allow for study of how the brain works. They can be used during brain surgery as well as when the patient is awake and conscious, as the brain itself does not sense pain during the measurements. Although electrophysiology has been around for close to half a century, it has attained appreciable advances only in the last two decades. These advances have revolutionized the study of brain structure and functions, allowing neurophysiologists to monitor the brain’s activities directly during experiments (Sutler et al., 1999). Even with its significant impact in neurology, however, its presence has been so commonplace that many people no longer realize its ubiquity. This essay explores three electrophysiological techniques namely patch clamp, sharp electrodes, and brain slice recording. It describes how each of these techniques works as well as how advances in the techniques have