Posted in Psychology & Medicine

Gait

In medicine, a person’s way of walking is termed gait. By analysing a person’s gait, a trained professional can gain insight into what pathologies the person may be suffering from. For example, just from the way the patient limps, the doctor may discover that the patient has an incurable degenerative brain disease.

The most common gait abnormality is the antalgic gait, or limping due to pain. Most people would have experienced the difficulty of walking with a sprained or broken ankle, muscle ache or knee problems. This is easy to spot as the patient quickly switches to the other feet when leaning on the affected leg due to the pain. Therefore, the side that stays on the ground less than the other is the affected leg.

Sometimes, you can see a person “waddling” along as they swing from one side to the other. This may be a waddling gait, also known as Trendelenburg’s gait, caused by a weakness in the hip muscles that support the pelvic girdle, either due to muscle or nerve damage. As the patient cannot support their weight on the affected side, their pelvis tilts towards the opposite side. To avoid falling over, the patient lurches their body towards the other side, causing them to waddle. Looking at the tilt and lurch gives insight into what side is affected.
Another rather common gait is the steppage gait, where the person lifts one leg higher than the other, while their foot drags on the ground. This is caused by nerve damage leading to the loss of ability to lift the foot up (termed foot drop).

As the brain controls the motor system, damage to the brain also leads to motor dysfunction. A common example is a stroke.
If the stroke damages a significant part of the motor cortex, the patient suffers from hemiparesis/hemiplegia, or weakness/paralysis of one half of the body. This causes the limbs on the affected side to stiffen, as seen by an extended leg pointing inwards and retracted arm. The patient has to swing the affected leg around while they walk as they cannot flex the hip, known as a hemiplegic gait.
If the cerebellum is damaged, balancing becomes an issue. This causes the patient to suffer from ataxia, where they cannot coordinate their movements and are prone to toppling over. These patients tend to sway violently from side to side as they try to walk in a straight line.

Lastly, degenerative brain diseases can also affect gait. There are two main examples.
In Parkinson’s disease, the patient suffers from what is called hypokinesia and bradykinesia – reduced and slow movement. This leads to a shuffling gait where the patient walks slowly by shuffling their feet in small steps. They are also stooped over and are often seen with a pill-rolling tremor of their hands – a cardinal symptom of the disease.
In Huntington’s chorea, the opposite (hyperkinesia) occurs. This causes flailing as the muscles contract in an uncoordinated manner, including both the arms and legs. Ergo, their gait is quite jerky and interrupted by bouts of flailing, termed choreiform gait, but their balance is fine so walking in a straight line is still possible.

Knowledge of these disorders may help one appreciate the suffering a patient walking along the street has to undergo everyday of their life.

(Video demonstrations: http://stanford25.wordpress.com/gait-abnormalities/)

Posted in Psychology & Medicine

Sleep Paralysis

Sometimes just before you fall asleep, or just after you wake up, it is impossible to move any muscles. The panic caused by this sudden paralysis is soon followed by a sense of impending doom and unknown horror. When trying to look around to figure out what is happening, you see a ghost or demon sitting on your chest, pinning you down.
This is a typical scenario of sleep paralysis. It occurs when the mind wakes up before the body (in loose terms) and is experienced by everyone at least once throughout their life. 

Sleep is divided into two phases: REM (rapid eye movement) sleep and non-REM sleep. These two phases cycle to make up sleep at a 1:3 ratio (i.e. about 90 minutes non-REM, 30 minutes REM, repeat). NREM sleep is often thought of as “shallow sleep”, but this is incorrect as the third phase of NREM is literally “deep sleep”. This is followed by REM sleep, characterised by relaxation of muscle tone and the eyes darting in all directions (rapid eye movements). The brain cuts off motor signals to the body during REM sleep to prevent it acting out the movements in a dream (without this, many people would injure themselves or others during sleep). For example, patients suffering from diseases such as Parkinson’s disease with REM sleep disorder show vigorous movements during sleep, often hitting their partners in the process.

The problem occurs when the onset of REM atonia (relaxation) comes before the person fully falls asleep, or fails to disappear after waking up. As the motor system has been shut down, the muscles cannot be moved yet the person has regained consciousness. The more frightening thing is that sleep paralysis is usually accompanied by an intense visual and auditory hallucination, which is almost always related the person’s worst nightmares and fears. This explains why so many cultures associate it with demons and ghosts, and it is also possibly the cause of alien abduction experiences and ghost sightings. Reason being, the hallucination is so vivid the person easily believes that it actually happened.

Sleep paralysis can be caused by excessive drinking, stress or the induction of lucid dreams, but tend to be spontaneous and can happen to you on any day.

Posted in Science & Nature

Parkinson’s Law

Parkinson’s Law states that the bigger a company grows, the more inefficient workers it will hire while paying out more wages. The reason for this is simple: those in power like to stay in power, and the best way to ensure this is to eliminate competition.

Hiring skilled workers brings upon the chance of a strong competitor that can over throw the bureaucrats, which is undesirable. Therefore, by hiring useless people, the bureaucrats are able to keep their seat of power.

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(from The Encyclopaedia of Relative and Absolute Knowledge by Bernard Werber)