Neuro Lect 9
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When the function of both cerebral hemispheres or the brainstem reticular activating system is compromised.
- loss of consciousness (LOC)
- Note : episodic dysfunction produces transient, and often recurrent LOC
What are the two major causes of loss of consciousness?
- Note: may be due to injury to reticular activating system or significant damage to cerebral hemispheres as well
Disorders characterized by excessive or over-synchronized discharges of cerebral neurons.
Loss of consciousness due to reduced blood supply to the cerebral hemisphere or brainstem resulting in flaccid unresponsiveness that lasts for <15 secs with no postictal confusion.
Episode of altered consciousness characterized by excessive or over-synchronized discharges of cerebral neurons.
Brief symptoms that may precede the onset of some seizures.
A group of disorders characterized by recurrent seizures.
A shift in the normal balance of excitation and inhibition that results in a "short-circuit" involving different parts of the brain, and is defined by the part of the brain involved and whether it affects consciousness or not.
What are the primary generalized (both hemispheres) seizures?
- atypical absence
What are the partial seizures (one hemisphere)?
- simple partial
- complex partial
- secondarily generalized
Who can get seizures?
Transient disturbances of cerebral function caused by electrical hypersynchronization of neuronal networks in the cerebral cortex with a lifetime probability of occurrence at approximately 3%. Affects approximately 1% of the population.
- seizure disorders
- Note: diagnosis is often made retrospectively since most episodes occur outside the medical setting
What are the key features of a seizure disorder?
- aura "usually"
- postictal state
What is the etiology for most seizures?
- primary CNS dysfunction
- underlying systemic disease
- drug induced
What are some conditions that can cause seizures in anyone?
- hypoglycemia: increased risk with serum glucose <30 mg/dl, or if levels drop too quickly
- hyponatremia: serum levels <120 meq/L, or a quick decrease in level (dehydration as pt who did a ruck march with hydroxycut)
- hyperosmolar states: non ketotic hyperglycemia, hypernatremia
- hypocalcemia: serum level <9.2 with/without tetany type seizure
- uremia: especially with rapid decline in kidney function
What are important things to focus on when evaluating a patient who has had a seizure as far as the history is concerned?
- was it a real seizure
- are there any risk factors (predisposition/epileptogenic factors like head trauma, stroke, tumor, AVM)
- are there any precipitating factors (sleep deprivation, drugs, alcohol)
What needs to be looked for/addressed as part of the physical exam on a patient who has had a seizure?
- signs of infection
- signs of systemic illness
- complete neuro exam
- labs (glucose, calcium, FTA-ABS, electrolytes, CBC, ESR, BuN, Cr, LFTs)
What is the confirmatory test used to identify seizures? How is it performed?
- EEG (confirms if positive but doesn't rule out if negative)
- conduct EEG under physiologic stress (sleep deprivation)
What are the subtle findings that make MRI superior to CT when neuroimaging patients with seizures?
- small tumors
- vascular deformities
In the ER, what neuroimaging on a patient presenting with seizures may be all that is necessary to rule out infection, masses or bleeding?
- noncontrast CT
- Note: pts with typical recurrent seizures do not require emergent or urgent imaging
Sometimes called petit mal seizures that cause short bouts of staring and a lack of awareness, and is most common in children.
absence seizures (non-convulsive disorder)
Type of seizure with no loss of consciousness/awareness that may produce abnormal sensations like a funny feeling/aura, unpleasant smell, or body movement like jerking of the arm.
simple partial seizures
Type of seizure that can cause loss of awareness, confusion, staring and motor symptoms such as hand rubbing, lip smacking, army positioning, uncontrolled shouting or swallowing.
complex partial seizures
Sometimes called grand mal seizures that can cause a fall to the ground followed by jerking movements. The patient will lose awareness during the episode and may or may not lose control of bowel or bladder. Episodes are usually preceded by an aura.
generalized tonic clonic seizures
Phase during a generalized seizure in which the body is extended (opisthotonos) that lasts about 30 seconds and possibly occurs with apnea.
Phase during a generalized seizure in which there is alternating muscle contraction and relaxation that lasts for 30-60 seconds or more. Patient may bite their tongue, and will have sphincter relaxation.
What is the recovery phase of a generalized tonic-clonic seizure?
- normal neuro exam
- postictal confusion up to 30 minutes
- todd paralysis (transient unilateral weakness in the postictal period)
Seizures that cause sudden jerking in the muscles of the arms and legs (most often) and is linked to a gene on chromosome 6.
What is the acute management of a seizure?
- place pt in recovery position to avoid aspiration
- observe (chance of recurrence ~30%)
- consider initiation of medical therapy (drugs)
- check drug levels periodically, esp if pt is having recurrent seizures
What are the medications used to initiate medical therapy in ACUTE management of a seizure?
- phenobarbital 60mg po BID/TID
- phenytoin 100mg po TID
- carbamazepine 200mg po BID
These seizures may involve clonic movements of a single muscle group in the face, limbs, or pharynx that may or may not spread (jacksonian march). An aura often precedes and consciousness may be preserved during the episode.
simple partial seizures
What are the most common type of seizures that affect six out of every ten people with epilepsy and can be difficult to control?
What are some of the physical/clinical features that can be observed during a partial seizure?
- staring into space
- unusual movements of the mouth and tongue
- sudden fear/rage/anger/joy
What are the autonomic symptoms of a partial seizure?
These seizures involve impaired consciousness, responsiveness, and memory. Patients commonly experience olfactory hallucinations or deja vu sensations that usually originiate from the temporal lobe.
complex partial seizures
What are some of the underlying conditions that cause seizures and need to be treated themselves in order to treat the seizures?
- metabolic disease
What are the precipitating factors that should be avoided to help treat seizures?
- sleep deprivation
- bright lights
- alcohol intake
- "reflex seizures"
Condition in which seizures can be provoked habitually by an external stimulus or less commonly, internal mental processes.
What are the first line medications used to treat partial seizures?
- phenytoin (dilantin)
- carbamazepine (tegretol, equetro only in ER)
- lamotrigine (lamictal)
What are the second line medications used to treat partial seizures?
valproic acid (divalproex & valproate sodium)
What are the first and second line medications used to treat absence seizures?
- first: ethosuximide (zarontin) 250mg po BID (can cause bone marrow suppression)
- second: valproic acid 250mg po TID
What are the first and second line medications used to treat generalized tonic-clonic seizures?
- first: valproic acid (depakote)
- second: lamotrigine (lamictal, carbamazepine (tegretol), phenytoin (dilantin)
Who is routinely responsible for managing seizure medications with follow ups and ensuring compliance?
PCP, not the neurologist
Prolonged seizure activity lasting 30 minutes or more. Can be due to a continuous seizure or discrete, recurring seizures with unconsciousness during the ictal period.
- status epilepticus
- Note: medical emergency, may cause brain injury or death, mortality rate for adults with first episode is 20%
What are the common causes of status epilepticus?
- drug toxicity
- anticonvulsant withdrawal/noncompliance
- metabolic disturbances (hypoglycemia)
- CNS infection
- CNS tumors
- refractory epilepsy
- head trauma
What is the emergency management for status epilepticus?
- maintain airway (insert oral airway, recovery position)
- IV access
- ECG, respiratory, blood pressure monitoring
- emergency eval of serial seizures/status epilepticus
- rule out likely causes
What are the labs and studies used to diagnose/monitory status epilepticus?
- electrolytes, glucose, BUN, creatinine
- calcium and magnesium
- toxicology screen
- anticonvulsant drug levels
- possible LP
What is the medical therapy used to treat status epilepticus?
- thiamine 100mg IM/IV and IV glucose (50mg of 50% dextrose)
- diazepam 0.1-0.2mg/kg IV (max dose 20mg) or lorazepam 0.1mg/kg IV (max dose 8mg)
- phenytoin 20mg/kg IV (with ECG monitor) or fosphenytoin 20mg/kg IV
- Note: seizures should be controlled within 30-40 minutes, if not then use anesthesia with midazolam, propofol, or pentobarbital
How are seizures that are recurrent on drug therapy managed?
- determine serum level of drug
- MRI to rule out structural lesion
- evaluate lifestyle factors that may be contributing
- change to a second drug
- referral to neurologist if seizures are not controlled within three months
- surgical excision, vagus nerve stimulation for refractory seizures
What are some of the drugs that can be added on top of the first drug if it achieved partial control of recurrent seizures?
What are the complications/restrictions for patients with epilepsy?
- no heavy machinery/heights
- no swimming alone
- are generally undereducated & underemployed for their level of function
- require 3-18 months seizure free before they resume driving
How often should CBCs and LFTs be performed to monitor anticonvulsant side effects of hematologic or hepatic toxicity?
- 2 weeks
- 1 month
- 3 months
- 6 months
- every 6 months there after
- **drug interactions are common!**
Seizures that are typically benign that may occur with temps above 102F. Occurs more often in males than females and lasts <5 mins in 40%, and <20 mins in 75%. Only 1-2% may develop epilepsy.
Epilepsy and anticonvulsant therapy during pregnancy increases the risk of what complications?
- mental retardation
- seizure disorders
- congenital malformations (cleft lip, palate, and cardiac anomalies)
Taenia solium infection of the CNS causing seizures (most common) in 30-90% of patients that have it.
What is the treatment for neurocysticercosis?
May be confused with seizure disorders because attacks resemble an epileptic seizure. However they have purely psychological causes therefore other seizure types need to be ruled out.
Trauma induced alteration in mental status (confusion, amnesia) with/without loss of consciousness that may last from minutes to hours with the severity of trauma usually being associated with the severity of symptoms.
What is the pathophysiology for concussions?
- cortical contusion: coup countercoup
- shear forces & tensile forces: trauma
- disruption of axonal transport leading to axonal swelling: releases excitatory neurotransmitters and increases free radical production
What is the pathophysiology of a concussion with bleeding?
- contusions: localized areas of bruising, swelling and mass effect, caused by direct external contact forces (fist), which slaps the brain against the cranium
- torn vein: subdural
- torn artery: epidural, intercerebral hemorrhage
What are the clinical features of a concussion?
- loss of consciousness
What are the typical symptoms of a concussion?
- lack of awareness
- mood changes
- light/noise sensitivity
- sleep disturbance
What are the signs of a worsening concussion?
- worsening headache
- focal neurologic signs
- worsening confusion
- impaired consciousness
- Note: all these signs point to a hemorrhage
Which grade of concussion presents with transient confusion for <15 mins, no loss of consciousness, and allows pt return to activities if cleared?
Which grade of concussion presents with transient confusion, no loss of consciousness, symptoms for >15 mins, and allows patients to return to activities in a week if there are no symptoms?
- grade 2
- Note: pt needs head CT or MRI and neuro exam if symptoms persist
Which grade of concussion presents with any loss of consciousness and requires an emergent CT/MRI and thorough neuro exam, and takes patient/athletic out of competition/activity for one to two weeks?
How long must an athlete who had a concussion with confusion >15 mins, any loss of consciousness, and post traumatic amnesia be asymptomatic before returning to play?
What are the three components of the military acute concussion evaluation (MACE)?
- history and symptoms
- screening neuro exam
- cognitive screen with score
What are the four sets of circumstances that will mean an automatic post-blast-stand-down of 24 hours and evaluation with the MACE care as identified by the Army Vice Chief of Staff and Office of the Army Surgeon General?
- mounted: Soldiers in a vehicle that is damaged during a blast are to be evaluated (if there is no damage to the vehicle evaluation is not required)
- dismounted: Soldiers standing or walking within 50 feet of a blast or who where inside a building/structure that was struck by an explosive device
- anyone who sustains a direct blow to the head or suffers a loss of consciousness in an explosion
- at a commander's discretion
What is the purpose and use of the MACE?
- to eval a person when a concussion is suspected
- to confirm the diagnosis and assess current clinical status
Who should always be evaluated with the MACE?
anyone who was dazed, confused, "saw stars", or lost consciousness
How are patients with a MACE score <25, PCS present managed?
re-evaluate in 24 hrs or evac to higher echelon of care
How are patients with a MACE score of 26-27, PCS symptoms present managed?
- locally but re-evaluate, including MACE
- if re-eval shows deterioration in symptoms or MACE score, evac pt to higher echelon of care
How are patients with a MACE score of >/= 28, with no PCS symptoms managed?
consider return to duty
What are the warning signs of a concussion?
- persistent confusion
- behavioral changes
- subnormal alertness
- extreme dizziness
- focal neurologic signs
Accumulation of blood in the subdural space from a bleed in the cerebral vasculature caused by a blow from front or back or when the skull hits a fixed object (ie windshield). The bridging veins between the dura and the arachnoid are torn when the two separate.
What is the pathophysiology of a subdural hematoma?
- venous blood is lower pressure and clots faster which continues increasing the size of mass
- stretching meninges causes the headache while the increasing pressure causes contralateral weakness
- irritation of the cerebrum may cause seizures
- gradual signs of cerebral compression occur hours to days to weeks after injury
- can be fatal!
Levels of impaired responsiveness to external stimulation that may be due to injury to the reticular activating system or significant damage to the cerebral hemispheres.
A state of "unarousable unresponsiveness".
A state in which a patient is midway between alertness and coma.
Neurons originating in the pons and midbrain projecting to the thalamus and cerebral hemispheres.
reticular activating system
What are the causes of stupor and coma?
- brainstem lesion
- cerebrovascular disease (SAH)
- meningeal irritation (meningitis, encephalitis)
- intoxications (sedative-hypnotics, alcohol, opioids)
- metabolic encephalopathy
- prolonged post-ictal state
- transtentorial herniation (expanding mass lesion, subdural/epidural hematoma)
What are the signs of uncal transtentorial herniation and how is it treated?
- contralateral pupillary changes (20% of cases)
- ipsilateral eye motor changes (compression of CN III)
- treatment: bilateral decompressive trephination ("burr holes") when trephination on the expected side doesn't yield results
What are differential diagnoses for an abrupt loss of consciousness?
- subarachnoid hemorrhage
What are differential diagnoses for a gradual loss of consciousness?
- brain tumor
- chronic subdural hematoma
What are differential diagnoses for fluctuating loss of consciousness?
- recurrent seizures
- metabolic encephalopathy
What does initial hemiparesis preceding LOC suggest?
structural lesion with mass effect
What do transient visual symptoms preceding LOC suggest?
posterior circulation ischemia
When evaluating a patient with LOC, what do previous attacks of LOC suggest?
What illnesses are suggested by fever with loss of consciousness
What illnesses are suggested by an increasing headache with loss of consciousness?
- intracranial mass
A patient who experienced recent falls suggests what?
A patient who experienced recent confusion or delirium suggests what?
metabolic or toxic cause
What should the general examination of a patient with stupor or coma include?
- vital signs: hyper/hypotension, hypo/hyperthermia
- ventilatory patter: hyper/hypoventilation, cheynes-stokes
- cutaneous/mucosal abnormalities: bruising, rashes, petechiae
- signs of trauma: bruising, hemotympanum, raccoon eyes, battle's sign
- CSF fluid: rhinorrhea or otorrhea
Posturing in which there is flexion of the hands, and elbows, adduction of the arms, extension of the knees and plantar flexion.
Posturing in which there is flexion of the hands, pronation of the forearm, extension of the elbows, adduction of the arms, extension of the knees and plantar flexion.
What is the Glascow coma scale for motor response?
- 6: obey commands fully
- 5: localizes to noxious stimuli
- 4: withdraws from noxious stimuli
- 3: abnormal flexion (decorticate posture)
- 2: extensor response (decerebrate posture)
- 1: no response
What is the Glascow coma scale for verbal response?
- 5: alert and oriented
- 4: confused, yet coherent speech
- 3: inappropriate words and jumbled phrases consisting of words
- 2: incomprehensible sounds
- 1: no sounds
What is the Glascow coma scale for eye opening?
- 4: spontaneous eye opening
- 3: eyes open to speech
- 2: eyes open to pain
- 1: no eye opening
Conjugate movement of the eyes in the direction opposite to the head movement in a comatose patient.
oculocephalic (doll's eyes) response
If a comatose patient does not have a doll's eyes reflex then a lesion be present where?
- afferent/efferent loop of the reflex arc
- Note: afferent consists of the labyrinth, vestibular nerve and neck proprioceptors; efferent consists of cranial nerves III, IV, and VI along with the muscles they innervate
What maneuver is used to assess extra-ocular muscles in a comatose patient with a possible cervical spine injury?
- cold calorics
- Note: place pt's upper body and head at 30 degrees off horizontal and inject 50-100cc of cold water into an ear, eyes should deviate to the ear with the injection (same effect as turning the patient's head)
What are the labs and studies used to evaluate a patient with stupor or coma?
- serum glucose, electrolytes, BUN/Cr (chem 7), LFT, PT/PTT, CBC, ABGs
- neuroimaging (CT provides quick assessment and is the test of choice for initial eval)
- lumbar puncture
What is the initial management of a patient with stupor or coma?
- intubation for GCS </= 8
- IV NS with 25g dextrose, 100mg thiamine, 0.4-1.2mg naloxone
- Note: see table 10-1 in the book
A transitional state that rarely lasts for more than several weeks. Patients either recover or evolve into a persistent vegetative state or brain death. Prognosis depends on underlying etiology for coma and other important factors including age.
What Glascow score indicates coma? What initial score leaves patients with a >95% incidence of death or persistent vegetative state?
- glascow scale of 3-8 are considered comatose
- glascow scale of 3-4 indicates >95% incidence of death or persistent vegetative state
Irreversible loss of function of the brain, including the brainstem.
What are the causes of brain death?
- primary neurologic disease caused by severe head injury or aneurismal subarachnoid hemorrhage
- hypoxic-ischemic brain insults
- fulminate hepatic failure
The cause of brain death must be demonstrably irreversible. What are these causes of brain death and their criteria?
- evidence of acute CNS event compatible with the clinical diagnosis of brain death
- exclusion of complicating medical conditions that may confound clinical assessment
- no drug intoxication or poisoning
- core temperature >/= 32C (90F)
What are the cardinal features of brain death?
- coma/unresponsiveness: no response to painful stimuli
- absence of brainstem reflexes: pupils, oculocephalic, gag, grimacing
- apnea: no respiratory attempts even with PCO2 >/= 60mmHg
What are some conditions that may interfere with the clinical diagnosis of brain death?
- severe facial trauma
- pre-existing papillary abnormalities
- toxic levels of sedative drugs, TCAs, and many other drugs
- sleep apnea or severe pulmonary disease result in chronic CO2 retention
- locked in syndrome
- Note: PAs can declare brain death in combat but only if in remote locations (BE CAREFUL AND DOCUMENT!)
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