Week 7: The Nervous System Part 2 Flashcards
Loss of consciousness
Describe how it occurs
-Fainting/ syncope (means the same thing)
-feeling faint without LOC = pre syncope
-occurs due to reduced global cerebral perfusion (rucked blood supply to the brain!)
2 common types:
A) vasovagal syncope (most common)
-peripheral vascular resistance reduction secondary to autonomic activity
B) cardiac syncope
-reduced cardiac output secondary to mechanical outflow obstruction, pump failure, harmony amicably significant arrhythmias, or aortic stenosis
What are the common motor/ sensory disorders?
Loss of consciousness / Syncope
Seizures & Epilepsy
Weakness:
Motor Neuron Disorders
Multiple Sclerosis
Other: incl. Muscular Dystrophies
Sensory changes:
Peripheral neuropathy
Spinal Nerve entrapment
Demyelinating disorders (MS)
Peripheral neuropathy & Diabetes mellitus
Parkinson’s disease
Stroke:
CVA and TIA
Seizures
Definition
Causes
Definition:
A seizure is a sudden disruption of the brain’s normal electrical activity accompanied by altered consciousness and/or other neurological and behavioral manifestations.
Causes:
A rapidly increasing fever (febrile convulsion) – common in infants/children
Severe hypoglycaemia eg. in Diabetes
Head injury or SOL
Alcohol or drug withdrawal
Infection (eg. meningitis or encephalitis; parasitic)
Epilepsy
What is it? What happens?
Causes?
What are the most common types of epilepsy are there?
Epilepsy is a recurrent tendency to have spontaneous, abnormal electrical activity in part of the brain, manifesting as seizures
Not all seizures are epilepsy!
Prevalence of epilepsy is around 1%
Diagnosis is very dependent on description of the “fits”
Causes of Epilepsy:
Idiopathic – some predisposition is genetic
Same as for seizures, EXCEPT fever, hypoglycaemia & infection (structural rather than temporary, metabolic causes) – however, alcohol and drug withdrawal can be a cause – due to permanent damage??
More Common Types of Epilepsy:
Absence Seizures (Petit Mal)➡ usually less than 20 seconds, sudden onset and termination, many are unaware they had an episode, most susceptible are children, difficult to detect, can have 50-100 times a day (just looks like their not paying attention)
Complex Partial Seizures ➡ normally occur in children, however they are th most common type of seizures in adults
- at beginning they may have a strange smell, taste, sound, or visual disturbance, and unexplained fear of anxiety or fear, or perhaps dejavu.
- changes the persons level of consciousness, person may appear awake but may not respond to anything, the person usually stares into space.
- seizures may include involuntary movements such as lip-smacking, chewing, picking, swallowing
- lasts 30 secs to 2 minutes.
Generalized T onic-Clonic Seizures (Grand Mal seizures)
- have vision, taste, smell, or sensory changes, hallucinations, or dizziness before the seizure (called an aura).
- usually involves muscle rigidity, followed by violent muscle contractions, and loss of alertness (consciousness)
- may bite cheek or tongue, clench teeth or jaw, loss of urine control, difficulty or stopped breathing, blue skin colour
- Post-ictal drowsiness occurs
What are causes of weakness?
Remember that UMN and LMN disorders result in weakness
- Mononeuropathy (LMN)
- Polyneuropathy (LMN)
Guillain-Barre Syndrome:
- an acute inflammatory demyelinating polyneuropathy (AIDP), an autoimmune disorder affecting the peripheral nervous system, usually triggered by an acute infectious process
Diabetic Polyneuropathy (to be discussed)
-neuropathy means nerve damage. Diabetes is most common cause. Feet usually go numb, there is no cure, treatment aims to ease symptoms and reduce risk of further complications
Myopathic disorders
➡ Muscular Dystrophy:
◦ a group of genetic, hereditary muscle diseases leading to progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue (necrosis)
◦ 9 different types, most common being Duchenne’s Muscular Dystrophy
◦ Progression of muscle weakness that tends to occur in a proximal-to-distal direction in most forms.
Remember Myasthenia Gravis? (previous self-study)
-autoimmune disease characterised by muscular weakness. The symptoms are caused by the immune system interfering with the transmission of messages from the nerves to the muscles. Cause not known, no cure
-symptoms: weak muscles, visual disturbances, droopy eyelids, fatigue, swallowing difficulties, breathing issues, shortness of breath
View slide 10
Multiple sclerosis
What is it, what’s its symptoms?
A relapsing & remitting disorder of plaques of demyelination (and axon loss)
Does not affect the peripheral nerves
Focal disruption of the blood-brain barrier associated with inflammatory response & myelin damage
Lifetime risk is around 1/1000, various per region of the world
Prognosis poor if:
◦ Numerous occurrences of relapse
◦ Motor signs first
◦ Male
Symptoms:
Typically, episodes occur months or years apart and affect different anatomic locations.
Eg. a patient may present with paresthesias of a hand that resolve, followed a few months later by weakness in a leg or visual disturbances (eg, diplopia).
The duration of the attack should be longer than 24 hours.
Other classic symptoms include:
Muscle cramping secondary to muscle hypertonicity
Bladder, bowel, and sexual dysfunction (autonomic NS)
Trigeminal neuralgia or Bell’s Palsy
Constitutional symptoms - especially fatigue (which occurs in 70% of cases) and dizziness
Diabetic Polyneuropathy
Sensory symptoms (A) Insidious (gradual) onset of bilateral parasthesias or nubmness in a glove-and-stocking distribution in the distal extremities.
Motor symptoms (B) Upper and lower limb bilateral weakness may occur, though usually minimal. May be noticed in proximal leg muscles eg. walking down stairs and shoulders Loss of vibration sense is common (bilaterally)
Motor neurone disease: (MND)
Group of diseases caused by the degeneration of the motor neurones in the motor cortex, cranial nerve nuclei & anterior horn cells
Some are hereditary, others occur spontaneously
UMNL and/or LMNL (ant horn cells)
NO sensory loss or sphincter dysfunction
Around 7/1000 incidence
Incurable
Amyotrophic Lateral Sclerosis
also known as “Lou Gehrig disease”
5-10% inherited
characterized by progressive skeletal muscle weakness and atrophy, spasticity, and fasciculations as a result of degeneration of the UMNs and LMNs, culminating in respiratory paralysis.
Parkinson's disease: Disorder of what? What increases your risk? Average age of onset? Ratio of men: women?
What are the 3 cardinal signs of Parkinson’s disease?
Disorder of the Basal Ganglia 10% are genetic Exposure to environmental toxins increases risk Average age of onset = 60 years Men 1.5: 1 Women
3 Cardinal Signs of Parkinson’s Disease:
- Tremor:
At rest, reduces with movement – (resting (static) tremor)
Known as a “Pill rolling tremor” - Rigidity:
Resistance to passive stretch throughout range of motion (lead pipe rigidity)
Tone may be broken by tremor (cog-wheel rigidity)
Differentiate from spasticity - Bradykinesia:
Slowness of movement
Difficulty initiating movement Monotonous speech
Shuffling gait
Cerebellar disease:
What if you get cerebellar lesions?
What are the signs of cerebellar disease?
Function of Cerebellum is to co-ordinate all movement and help maintain upright posture
Cerebellar “lesions”:
Stroke
SOL (tumour)
VANISH DDT:
Vertigo
Ataxia
Nystagmus
Intention tremor (though static (postural) tremors also occur)
Staccato speech ( a form of dysarthria)
Hypotonia
Dysdiadochokinesia (reduced rapid-alternating movements)
Dysmetria (past pointing – difficulty with point-to-point movements)
Titubation
Stroke Results from? Causes? Risk factors? Warning signs?
Cerebrovascular Accident (CVA)
Results from infarction or bleeding into part of the brain, manifest by rapid onset (over minutes) of focal neurological signs & symptoms
Increased risk with age, incidence 1.5/1000
Causes:
◦ Thrombosis in situ
◦ Heart emboli
◦ Arteriothromboembolism
◦ CNS bleed (trauma, aneurysm rupture) – haemorrhagic stroke
The cost burden of stroke in Australia is estimated to be around $2.14 billion a year!²
Risk factors:
Hypertension
Hypercholesterolemia
Smoking
Diabetes
Obesity
Exercise (reduces risk!)
Heavy alcohol consumption
Warning signs:
Sudden:
Numbness or weakness of the face, arm or leg
Confusion, slurred speech
Ataxia, dizziness, loss of co-ordination
Visual loss or diplopia
Severe headache
TIA (transient ischaemic attach)
What is it?
Sudden onset of focal CNS signs or symptoms due to temporary occlusion, usually by emboli, of part of the cerebral circulation (duration usually s may be caused by arterial vasospasm
TIA is like Angina is to a Myocardial Infarction!
Often a precursor to Stroke
Signs & Symptoms
◦ Single or many attacks
◦ Weakness, dysphasia, dysarthria, hemianopia (temporary)
◦ Hemiparesis, hemisensory loss (temporary)
Further research:
B12 Polyneuropathy
Neurological dysfunction due to dietary insufficiency of vitamin B complex
- deficiency damages the myelin sheath surrounding nerves= cessation of function
- lack of coordination, pain, numbness, sensory loss and weakness
- increase B12 in diet, injections
Further research:
Guillian-Barre Syndrome
Guillain-Barrè syndrome is an autoimmune condition. It is a form of nerve inflammation resulting in a spreading paralysis.
-antibodies and lymphocytes attack peripheral nerves= weakness. Paralysis + abnormal sensation of pain
-occurs rapidly
-no cure
The cause is unknown, but the trigger seems to be certain acute viral or bacterial infections. Most people recover, but it may take two years or more. There is no cure. Treatments such as plasmapheresis and gammaglobulin infusions can help recovery.
Neurofibromatosis
Growth of tumorus on nerve tissue
Types:
NFI (tumor on nerve tissue)
NFII (mutation on chromosome 22 affecting protein that stops tumour growth
-removal of tumours through surgery
Summary
Neurofibromatosis describes two different genetic conditions. NF1 (also called von Recklinghausen’s disease) is the most common. The two types are caused by variations (mutations) in different genes, which may be inherited or may have occurred at conception. Signs and symptoms may include neurofibromas or lumps anywhere on the body, learning difficulties, scoliosis and hearing loss.
