Posted in Psychology & Medicine

Phantom Limb Pain

In up to 80% cases of amputations, a strange phenomenon occurs where the amputee reports sensation or even severe pain where the limb has been amputated. It was noticed in field hospitals during wars when a soldier would wake up and ask someone to scratch his leg – which was no longer attached to his body. The sensation can be so powerful that victims actively believe that their phantom limb can interact with real objects. For example, there have been case reports of patients trying to pick up a cup with an amputated arm and becoming frustrated with their inability to.

Phantom limb pain may persist even after the amputee realises the limb is no longer there. The basis for phantom limb pain is a neurological system called the cortical homunculus. The cortical homunculus is a concept that the part of the brain responsible for sensation and movement is mapped out so that each part corresponds to a part of the body (see picture). For example, the top of the primary somatosensory and motor cortices (said parts of the brain) is responsible for foot sensation and movement while the side receives information from and sends signals to the face. It lets the brain construct an image of what the body looks like from sensory information it collates from various body parts. It is suggested that phantom limb pain is caused by a remapping of the cortical homunculus, fooling the brain to think that the limb is there even if it has been physically cut off. This also explains a similar condition called supernumerary phantom limb, where the brain believes there is an extra limb (e.g. a third arm).

As the homunculus concept is a recent idea, treatment options had not advanced much until the late 1990s. In 1998, a neuroscientist called Dr. Vilayanur S. Ramachandran devised a method called the mirror box treatment. He noticed that victims of phantom limb pain (PLP) had paralysis or pain in the limb just before the amputation (such as tightly gripping something before the arm got blown up by a mine), suggesting that PLP may be a form of learned paralysis. This means that the brain believes that the arm is still paralysed and any movement causes an uncomfortable sensation as the brain thinks the limb is contorted into a painful position. To fix this problem, Dr. Ramachandran invented a box with two holes, each going into a separate compartment. One compartment is for the good arm while the other has a mirror positioned on an angle to reflect the other arm (instead of seeing the stub they put in the hole). He would then instruct the patient to perform symmetric movements with both hands while looking at the reflected arm. For example, he would tell the patient to squeeze their “fists” tightly as possible and then let go. Through this procedure, the brain is retrained to let go of the perceived paralysis and pain as it is tricked in to thinking that the arm is healthy again. The mirror box therapy drastically improved the outcome and quality of life of PLP patients through the power of illusions.


Posted in Psychology & Medicine


Diabetes is a common and serious disease that is caused by the body being unable to control the blood sugar (glucose) level, leading to severe organ damage. For example, blood vessel damage can lead to blindness, renal failure, heart attacks or strokes. Diabetes is divided into Type 1, caused by the destruction of pancreatic β-cells (that produces insulin) leading to insulin deficiency, and Type 2 diabetes, where insulin resistance renders the hormone useless. Thus, diabetes is a disease related to insulin. So what is insulin?

Insulin is a hormone that lowers blood glucose. It has the important function of controlling blood glucose levels after a meal. Therefore, a diabetes patient has high blood glucose, which has a toxic effect.
As type 1 diabetics cannot produce insulin, they require daily insulin injections. Some type 2 patients also need insulin. But this hormone that saves the lives of diabetics also has a deadly dark side.

Too much insulin leads to hypoglycaemia due to its blood glucose lowering properties. This is the opposite of what happens in diabetes, but is even more dangerous. Although there are in-built autonomic defence mechanisms to prevent this from happening, a high level of insulin can overcome this to cause blood glucose to plummet. 
A hypoglycaemic patient initially suffers cognitive dysfunction, then sweating and tremors. As blood glucose falls further, the patient begins to convulse, until they fall into a coma and eventually die. This is because the brain heavily relies on glucose for its functions, and a disruption of glucose supply causes it to shut down.
Because blood glucose fluctuates much like blood pressure, it is hard to control. This leads to many diabetics accidentally falling into hypoglycaemia, or even losing their lives. Furthermore, insulin is sometimes used by people to cause hypoglycaemia as a means of suicide.

If you see a person convulsing, check around for any hypodermic needles or bottles of insulin. A diabetic patient would have a medic alert bracelet, and if it is a suicide attempt they would have recently injected themselves with insulin. If you think it is hypoglycaemia, you must immediately treat the patient as severe complications can occur in a very short time. The emergency treatment is quite simple – raise the blood glucose. For example, dissolving a spoon of white sugar in the patient’s mouth or making them drink a sugary drink such as apple juice can cause a spike in blood glucose, causing the symptoms to disappear. If their consciousness does not return, you may need to repeat the process until their blood glucose is high enough.

Knowing even a little about insulin and hypoglycaemia may lead to you saving a person’s life someday.