Difference between revisions of "Tremors and Movement Disorders (Nervous System) - Pathology"
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− | + | {{review}} | |
+ | |||
+ | {{toplink | ||
+ | |backcolour = E0EEEE | ||
+ | |linkpage = Nervous System - Pathology | ||
+ | |linktext =Nervous System | ||
+ | |maplink = Nervous System (Content Map) - Pathology | ||
+ | |pagetype =Pathology | ||
+ | }} | ||
+ | <br> | ||
+ | ==Tetanus== | ||
+ | |||
+ | * In a pathological context, '''"tetanus" is an infectious disease caused by the bacterium [[Clostridium tetani|''Clostridium tetani'']]'''. | ||
+ | ** Physiologically, the term "tetanus" refers to continuous sustained muscle contraction. | ||
+ | *** The disease caused by [[Clostridium tetani|''Clostridium tetani'']] is characterised by this feature. | ||
+ | |||
+ | ===Pathogenesis=== | ||
+ | |||
+ | * [[Clostridium tetani|''Clostridium tetani'']] generally cause infection via wound contamination. | ||
+ | ** Cuts or deep puncture wounds are most commonly infected. | ||
+ | * [[Clostridium tetani|''Clostridium tetani'']] produces tetanospasmin, a neurotoxin. | ||
+ | ** Tetanospasmin inhibits the release of the neurotransmitters GABA and glycine from interneurons in the spinal cord and brain. | ||
+ | * Without the usual inhibitory influence of glycine and GABA, there is increased excitation of the brainstem and motor neurons. | ||
+ | ** This leads to unopposed muscle contraction. | ||
+ | *** The frequency of action potentials at the neuromuscular junctions increases above a threshold. | ||
+ | *** Above this threshold, muscle fibres enter a state of tetanus. | ||
+ | **** Muscle spasm is initially present in the muscles of the jaw. | ||
+ | **** This is followed by a difficulty in [[Deglutition|swallowing]]. | ||
+ | **** General muscle stiffness and spasms then develop in other parts of the body. | ||
+ | ** Other effects may include: | ||
+ | *** Seizures | ||
+ | *** Effects on the autonomic nervous system | ||
+ | |||
+ | ===Diagnosis=== | ||
+ | |||
+ | * Diagnosis is made by taking into account the animal's: | ||
+ | ** History | ||
+ | ** Clinical signs | ||
+ | * Very rarely a wound where the bacteria may have entered may be seen. | ||
+ | |||
+ | ===Treatment=== | ||
+ | |||
+ | * Wound debridement | ||
+ | ** Surgical removal of dead and infected tissue from the wound. | ||
+ | * Antibiotic treatment. | ||
+ | ** Metronidazole | ||
+ | *** Treatment with metronidazole decreases the number of bacteria but has no effect on the bacterial toxin. | ||
+ | *** Metronidazole is particularly active against anaerobic bacteria, and so is a good choice for use against [[Clostridium tetani|''C. tetani'']] | ||
+ | ** Penicillin | ||
+ | *** Penicillin is becoming a less favoured treatment for tetanus, since there is a theoretical risk of increased spasms. | ||
+ | * Muscle relaxants | ||
+ | ** Diazepam | ||
+ | ** Midazolam | ||
+ | * Supportive therapy, for example: | ||
+ | ** Administering fluids | ||
+ | ** Providing appropriate nutrition | ||
+ | ** Maintaining a quiet environment with dimmed light. | ||
+ | * Remission take several weeks to months | ||
+ | |||
+ | ==Tetany== | ||
+ | |||
+ | * Tetany is variable intermittent muscle contraction. | ||
+ | |||
+ | ===Causes=== | ||
+ | |||
+ | * Stricnine poisoning. | ||
+ | * Hypocalcemia | ||
+ | ** For example, due to: | ||
+ | *** Parturition | ||
+ | *** Hypothyroidism | ||
+ | * Glycine disorders, in: | ||
+ | ** Humans | ||
+ | *** Knowns as startle disease or hyperexplexia. | ||
+ | *** Causes sudden contraction of primarily antigravity muscles | ||
+ | ** Arabian horses | ||
+ | |||
+ | ==Myoclonus== | ||
+ | |||
+ | * Myoclonus is sudden contraction of muscle followed by relaxation. | ||
+ | * There are several different types of myoclonus. | ||
+ | ** Sporadic | ||
+ | ** Repetitive | ||
+ | ** Constant | ||
+ | ** Action related | ||
+ | *** Congenital | ||
+ | *** Acquired | ||
+ | ** Postural | ||
+ | ** Episodic | ||
+ | ** Resting | ||
+ | |||
+ | ===Sporadic Myoclonus=== | ||
+ | |||
+ | * Sporadic myoclonus occurs as a reflex response. | ||
+ | ** A sudden response to an auditory stimulus. | ||
+ | |||
+ | ===Repetitive Myoclonus=== | ||
+ | |||
+ | * In repetitive myoclonus, contractions and relaxations are rhythmic. | ||
+ | ** They occur one to two seconds apart. | ||
+ | ** May occur when the animal is at rest or during movement. | ||
+ | * Repetitive myoclonus may be due to a functional disturbance of lower motor neurons. | ||
+ | ** This may be caused, for example, by distemper or another encephalomyelitis. | ||
+ | |||
+ | ===Action-Related Myoclonus=== | ||
+ | |||
+ | * Tremors are induced by movement. | ||
+ | ** Myoclonus disappears when the patient is relaxed or sleeping. | ||
+ | * May be caused by: | ||
+ | ** Cerebellar conditions | ||
+ | ** Myelin defects | ||
+ | ** Toxic insult | ||
+ | ** Problems with neurons | ||
+ | |||
+ | ====Congenital==== | ||
+ | |||
+ | * Results from: | ||
+ | ** Hypo- or dys-myelination | ||
+ | ** Storage diseases | ||
+ | * Samoyeds, springer spaniels and dalmations are predisposed. | ||
+ | |||
+ | ====Acquired==== | ||
+ | |||
+ | * Maltese terrtiers and West Highland white terriers are predisposed. | ||
+ | ** Gives rise to the name "white shakers" for the sufferers. | ||
+ | * Caused by meningoencephalitis. | ||
+ | ** Toxicosis is a common cause of meningoencephalitis, for example: | ||
+ | *** Metaldehyde | ||
+ | *** Pyrethrins | ||
+ | *** Hexachlorophene | ||
+ | *** Organophosphate | ||
+ | *** Food born mycotoxins | ||
+ | *** Macadamia nuts | ||
+ | * Takes the form of postural repetitive myoclonus. | ||
+ | ** Postural muscles are affected while they are supporting weight. | ||
+ | * The young and old are differentially affected. | ||
+ | ** Young animals | ||
+ | *** The head and neck are affected. | ||
+ | **** Gives head bobbing, which stops when the animal is distracted. | ||
+ | *** Most common in Dobermans, English Bulldogs and Boxers. | ||
+ | ** Aged dogs | ||
+ | *** Pelvic limbs are affected, although only when standing. | ||
+ | **** Orthostatic tremors | ||
+ | *** Whole muscles are affected. | ||
+ | *** Most common in Great Danes. | ||
+ | * Aquired action-related myoclonus is responsive to steroid or immunosuppressive drugs. | ||
+ | |||
+ | ===Other Conditions Giving Myoclonus=== | ||
+ | |||
+ | * Scottie cramp | ||
+ | * Cavalier King Charles Spaniel hypertonicity | ||
+ | * Norwich terriers have a predisposition. |
Revision as of 11:27, 12 May 2010
This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing. |
|
Tetanus
- In a pathological context, "tetanus" is an infectious disease caused by the bacterium Clostridium tetani.
- Physiologically, the term "tetanus" refers to continuous sustained muscle contraction.
- The disease caused by Clostridium tetani is characterised by this feature.
- Physiologically, the term "tetanus" refers to continuous sustained muscle contraction.
Pathogenesis
- Clostridium tetani generally cause infection via wound contamination.
- Cuts or deep puncture wounds are most commonly infected.
- Clostridium tetani produces tetanospasmin, a neurotoxin.
- Tetanospasmin inhibits the release of the neurotransmitters GABA and glycine from interneurons in the spinal cord and brain.
- Without the usual inhibitory influence of glycine and GABA, there is increased excitation of the brainstem and motor neurons.
- This leads to unopposed muscle contraction.
- The frequency of action potentials at the neuromuscular junctions increases above a threshold.
- Above this threshold, muscle fibres enter a state of tetanus.
- Muscle spasm is initially present in the muscles of the jaw.
- This is followed by a difficulty in swallowing.
- General muscle stiffness and spasms then develop in other parts of the body.
- Other effects may include:
- Seizures
- Effects on the autonomic nervous system
- This leads to unopposed muscle contraction.
Diagnosis
- Diagnosis is made by taking into account the animal's:
- History
- Clinical signs
- Very rarely a wound where the bacteria may have entered may be seen.
Treatment
- Wound debridement
- Surgical removal of dead and infected tissue from the wound.
- Antibiotic treatment.
- Metronidazole
- Treatment with metronidazole decreases the number of bacteria but has no effect on the bacterial toxin.
- Metronidazole is particularly active against anaerobic bacteria, and so is a good choice for use against C. tetani
- Penicillin
- Penicillin is becoming a less favoured treatment for tetanus, since there is a theoretical risk of increased spasms.
- Metronidazole
- Muscle relaxants
- Diazepam
- Midazolam
- Supportive therapy, for example:
- Administering fluids
- Providing appropriate nutrition
- Maintaining a quiet environment with dimmed light.
- Remission take several weeks to months
Tetany
- Tetany is variable intermittent muscle contraction.
Causes
- Stricnine poisoning.
- Hypocalcemia
- For example, due to:
- Parturition
- Hypothyroidism
- For example, due to:
- Glycine disorders, in:
- Humans
- Knowns as startle disease or hyperexplexia.
- Causes sudden contraction of primarily antigravity muscles
- Arabian horses
- Humans
Myoclonus
- Myoclonus is sudden contraction of muscle followed by relaxation.
- There are several different types of myoclonus.
- Sporadic
- Repetitive
- Constant
- Action related
- Congenital
- Acquired
- Postural
- Episodic
- Resting
Sporadic Myoclonus
- Sporadic myoclonus occurs as a reflex response.
- A sudden response to an auditory stimulus.
Repetitive Myoclonus
- In repetitive myoclonus, contractions and relaxations are rhythmic.
- They occur one to two seconds apart.
- May occur when the animal is at rest or during movement.
- Repetitive myoclonus may be due to a functional disturbance of lower motor neurons.
- This may be caused, for example, by distemper or another encephalomyelitis.
Action-Related Myoclonus
- Tremors are induced by movement.
- Myoclonus disappears when the patient is relaxed or sleeping.
- May be caused by:
- Cerebellar conditions
- Myelin defects
- Toxic insult
- Problems with neurons
Congenital
- Results from:
- Hypo- or dys-myelination
- Storage diseases
- Samoyeds, springer spaniels and dalmations are predisposed.
Acquired
- Maltese terrtiers and West Highland white terriers are predisposed.
- Gives rise to the name "white shakers" for the sufferers.
- Caused by meningoencephalitis.
- Toxicosis is a common cause of meningoencephalitis, for example:
- Metaldehyde
- Pyrethrins
- Hexachlorophene
- Organophosphate
- Food born mycotoxins
- Macadamia nuts
- Toxicosis is a common cause of meningoencephalitis, for example:
- Takes the form of postural repetitive myoclonus.
- Postural muscles are affected while they are supporting weight.
- The young and old are differentially affected.
- Young animals
- The head and neck are affected.
- Gives head bobbing, which stops when the animal is distracted.
- Most common in Dobermans, English Bulldogs and Boxers.
- The head and neck are affected.
- Aged dogs
- Pelvic limbs are affected, although only when standing.
- Orthostatic tremors
- Whole muscles are affected.
- Most common in Great Danes.
- Pelvic limbs are affected, although only when standing.
- Young animals
- Aquired action-related myoclonus is responsive to steroid or immunosuppressive drugs.
Other Conditions Giving Myoclonus
- Scottie cramp
- Cavalier King Charles Spaniel hypertonicity
- Norwich terriers have a predisposition.