The nervous system is made up of neurons which pass messages electrically through the brain, spine and peripheral nervous system. The central nervous system (CNS) is compromised of the brain and spinal cord. The peripheral nervous system (PNS) is made of any nerves which branch out from that toward the peripheries. The nervous system has 3 main functional divisions; motor, sensory and reflexive. The motor pathway receives and sends messages which give us control over our movement. In a physical exam this is tested via co-ordination tests and palpation for muscle bulk and tone. The sensory pathway sends and receives sensations. Pain, temperature and crude touch travel up the spinothalamic tract and the posterior column takes vibration, soft touch and position sense. The sensory pathway is tested by touching the patient with soft objects, painful ones and vibrating ones whilst their eyes are closed. They are also given objects to describe by feeling them in their hands and numbers are written on the hand using something with a point (stereognosis). The reflexes by-pass the brain and travel through a reflex arc. They are tested by tapping the reflexive tendon with a patella hammer.
Physical examination
It is best with this exam to perform it firstly on the top half of the body and then the lower half after. This prevents the patient from having to completely remove their clothes at any given point. There are 4 parts to this examination; motor, sensory, co-ordination and reflexes.
Begin by observing the patients gait. Have them walk up and down the room normally then on their heels followed by their toes then small steps touching the heel to the toe each time (pigeon steps). Have the patient hop on one leg then crouch on one leg (perform on both sides and make sure you can catch any falls).
Have the patient remove their top if you cannot see their arms and shoulders. Feel for bulk in the hands arms and shoulders a loss of muscle bulk may be due to polio, paralysis or injury. Move the arm around feeling for tone hypertonia (high tone) may indicate an upper motor neuron lesion, hyperthyroidism or amphetamine use. Hypotonia (low tone) may indicate a low motor neuron lesion or hypothyroidism. Test the strength of each muscle groups, fingers (grip, thumb opposition and finger abduction), wrists, bicep, tricep, abduction & adduction of arms, shrug the shoulders and turn the head. All of these must be performed against resistance and one must try to overcome the strength of the patient and push them to their limits or else it is very difficult to observe any asymmetry in muscle strength.
The peripheral senses are tested by touching the patient on certain dermatomes with a soft thing or a sharp thing, the patient has their eyes closed and must identify the sensation. If there is a problem feeling these one must perform a hot or cold test (temperature). Ask the patient to close their eyes and place a vibrating tuning fork on their thumb knuckle (or big toe) and ask them to identify the sensation. If this is achieved most distally it is not necessary to go more proximal. A common cause of sensation loss is glove and stocking syndrome caused by alcoholism or diabetes this spreads evenly up the arm from the peripheries toward the heart. If the patient can feel pain and temperature their spinothalamic tract is intact and if they feel vibration and soft touch their posterior column is unaffected. It is hard to say what may cause damage to these columns so it is best to describe harm as a ‘lesion’ to these areas so I specialist can make a diagnosis. Position sense is tested by moving the fingers (or toes) up and down with the patients eyes closed; this is disturbed in posterior column lesions. Then place an object in the patients hand to identify followed by writing a number in the patient hands with a pointed object; this is difficult for those with glove and stocking syndrome, co-ordination difficulties such as Parkinson’s, or numbness caused by stroke, trauma, alcoholism or multiple sclerosis.
To test co-ordination in the upper body ask the patient to rapidly turn their hands over on their lap. When a patient cannot do this it is called dysdiadochokinesis (lack of co-ordination) and can indicate cerebellar disease. Have them touch their nose then your finger as quickly as possible then begin to move your finger so they have to stretch to reach it (this is the only way an intentional tremor is noticed; a sign of multiple sclerosis and Wilsons disease). Have the patient stand up with their feet together and eyes closed for at least 30 seconds (this is called Romberg’s test) a positive one i.e. falling over or uneasiness indicates a loss of position sense. Follow this by having the patient stand with their hands out and palms up watching they do not drift from one point, then push the hands down and see if the patient corrects their position correctly (this is called pronator drift).
There are 3 reflexes for both the upper and the lower part of the nervous system exam. For the upper body there is the ulnar, bicep and tricep reflexes and for the lower there is the knee, ankle and plantar reflexes. Hyperreflexia can indicate hyperthyroidism, brain damage through amphetamine use, upper motor neuron damage, multiple sclerosis and alcoholism. Hyporeflexia is quite normal but can indicate hypothyroidism, lower motor neuron damage, guillaine-barre syndrome, polio. Pendular reflexes may indicate cerebellar disease.
Nervous System Pathologies
Alcoholism (the bodies dependence on alcohol) can cause great damage including liver failure, liver cirrhosis, pancreatitis, epilepsy, polyneuropathy, alcoholic dementia, heart disease, nutritional deficiencies, chronic gastritis, diabetes (type 2), anaemia, cancer (mouth, trachea and oesophagus), ataxia (loss of balance), cravings, panic, anxiety, psychosis, hallucinations, delusions and sleep disorders.
Stroke is caused by an embolism which stops blood supply to some part of the brain. It causes different symptoms depending where in the brain is being affected. It may produce pronator drift, face weakness, abnormal speech, sometimes numbness, reduction in sensory or vibratory sensation, loss of coordination and it may affect the senses.
Parkinson’s is a degenerative disease affecting the central nervous system. It is due to an under activity of the basal ganglia stimulating the motor cortex and under production of dopamine. It can cause cogwheel rigidity, a resting tremor (pill rolling), bradykinesia, akinesia, postural instability and small steps when walking.
Meningitis is inflammation of the brain meninges caused by infection. It causes a severe headache, nuchal rigidity, high fever, photophobia (sensitivity to light), phonophobia (sensitivity to sound) and a rash. A positive Brudzinsky or Kernig’s sign (painful rigid raising of either the head or legs when the opposite is raised) may indicate meningitis.
Multiple sclerosis (MS) is caused by demyelination and scarring of the myelin sheaths surrounding the axons in the brain and spinal cord. It causes fatigue, cognitive impairment, depression, mood swings, nystagmus, optic neuritis, diplopia, dysarthia, dysphagia, muscle weakness, spasms, constipation, diarrhoea, and constipation, frequency of urination or retention of urine.
Epilepsy is characterised by seizures caused by synchronous neuronal activity in the brain. Usually it is seen in young children or patients over 65.
Myasthenia Gravis has a prevalence of 4 in 100,000 and is twice as prevalent in women as men. The cause is unknown. It presents with fatigability, proximal limb muscles, extra ocular muscles, mastication, speech and facial expression muscles are the first to become affected.
Depression is theorised to be caused by low levels of 5-HT (serotonin); a neurotransmitter. In the case of SAD (seasonal affective disorder) this is caused by low levels of melatonin (a hormone) being produced by the pineal gland which helps trigger serotonin. Serotonin does not just govern our mood either, it also is found in the GIT where it contributes to our rate of bowel movements, nausea and vomiting reflexes. This is probably why appetite alters with depression. It may cause anorexia, weight gain, and weight loss, loss of libido, insomnia, fatigue and low mood.
Herbs for the Nervous System
Centella asciatica has an affinity for the brain as does Gingko biloba.
Hypericum perforatum is well known for its affects of serotonin levels.
Zingiber officinalis is a less well known herb for its affect on serotonin but this may be the mechanism by which it helps in nausea and vomiting in pregnancy.
No comments:
Post a Comment