PSYC 444 Lecture Notes - Lecture 9: Suprachiasmatic Nucleus, Glasgow Coma Scale, Traumatic Brain Injury
14 May 2018
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PSYC 444 – LECTURE 9
When patients are admitted into the ICU, the primary concern is to ensure that the patient survives and has an optimal recovery. However, sleep is rarely considered
to be an integral part of that recovery, despite it being central for cognitive health.
Traumatic brain injury often comes with extensive damage to both the brain itself and its connections. Thus, it must be regenerated.
TRAUMATIC BRAIN INJURY (TBI)
TBI: an alteration in brain function, or other evidence of brain pathology, caused by an external force
• Brief period of confusion or loss of consciousness
• Brain pathology: neuroimaging confirmation of brain damage
• Movement that causes brain to hit the inside of the skull, followed by a counterblow
Primary insult (biomechanical forces)
• Focal lesions
• Diffuse axonal injury
Secondary insult (biomolecular and physiological changes)
• Elevated intracranial pressure
• Production of free radicals
• Inflammatory cascade
Secondary insult onset may be hours to days after TBI induced by primary insult.
TBI SEVERITY
Moderate and severe TBI patients must be put in the intensive care unit in order to recover from their injuries. This is the primary difference from mild TBI.
• 90% confirmation using neuroimaging
• Includes post-traumatic amnesia (PTA), which is a state of confusion, agitation and disorientation
o Patients with PTA cannot make new memories, and often do not know where he/she is
o PTA compromises recovery
Glasgow Coma Scale (GCS): assesses severity of TBI using verbal, ocular and motor response measures.
• Maximum score of 15, minimum score of 3 (comatose patients)
TBI CONSCIOUSNESS
TBI typically alters consciousness, but what is consciousness?
Consciousness generally constitutes of two major aspects (on a spectrum)
1. Wakefulness: ability to wake up
2. Awareness: ability to integrate stimuli from own body and environment
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Locked-in syndrome: patients are fully aware and awake but because of a disconnection between the brain and body, they cannot move voluntarily (trapped in body)
General anesthesia: there are some cases of patients remembering bits of surgical procedure or emotions during the procedure. Thus, cannot be sure that awareness
is fully suspended under anesthesia.
Unresponsive wake syndrome (vegetative state): sleep-wake cycles are present but patients are not focused on anything; they are non-responsive to the
environment
Minimally conscious state (MCS): patients have more awareness and are able to talk. However, they are not integrating information and lack functional use of
objects. For example, patients would use a fork as a brush.
Moderate and severe TBI begin as a state of coma or induced coma, which is an artificial comatose state induced using sedatives (ensures that intracranial pressures
remain low). Over time, patients become more medically stable and transition through stages, eventually reaching normal consciousness. There are individual
differences: some patients may take longer to reach normal consciousness; some patients may skip stages, etc.
Generally, most patients eventually return to normal level of consciousness.
ACUTE PHASE OF TBI
Over time, patients emerge from continuous sedation and achieve medical stability, waking up on their own.
Once stabilized, they are moved to the neurological unit.
• At the neurological unit, patients undergo physical and occupational therapy to re-learn basic skills.
• May be in a state of post-traumatic amnesia, which can last well into the rehab period post discharge.
ACUTE RECOVERY
The acute phase (first six months) of TBI is crucial to the recovery process. If there is something hindering recovery during this period, it will most likely hinder life-
long recovery. This is because most of recovery primarily occurs during this period.
• Example: ability to regain certain abilities, including functional
Even though moderate and severe TBI represents only 10% of all TBI, they are a major cause of disability in industrialized countries.
• Many patients with moderate and severe TBI never return to school/work
Long term:
• Functional and cognitive deficits
• Behavioral and psychological changes
• Risk of psychiatric and neurodegenerative disorders
TBI AND SLEEP-WAKE DISTURBANCES
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Sleep-wake disturbances last several years after the TBI. Up to 50% patients in chronic phase will have trouble sleeping at night and staying awake during the day.
• Excessively tired, fatigued
• Must take multiple naps to remain awake throughout the day
• Impossible to return to prior work and school schedule
However, the origin, impact on recovery, and manifestation in earlier phases of recovery are all unknown.
For the brain to repair itself after TBI, sleep is essential!
SLEEP
Sleep: a reversible state with structural organization (sleep architecture).
• Stages: consists of measurable behavioral and physiological traits
• REM sleep: paradoxical sleep consisting of rapid-eye movements
• NREM: N1, N2 and N3
Polysomnography (PSG) is somewhat invasive, and patients must be collaborative
• Electrodes must be kept on throughout the night
• This is challenging with TBI patients
ACTIGRAPHY
Actigraphy: indirect measure of the sleep-wake cycle through rest-activity cycle (physical motion)
• Non-invasive, inexpensive alternative to PSG that is much easier to measure
• The actigraphy watch is worn on the non-dominant wrist for up to months, in order to see how sleep cycles evolve over time
Blue = night; yellow = day
Black lines: quantity of movement per minute
Each row is a separate day
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Document Summary
When patients are admitted into the icu, the primary concern is to ensure that the patient survives and has an optimal recovery. However, sleep is rarely considered to be an integral part of that recovery, despite it being central for cognitive health. Traumatic brain injury often comes with extensive damage to both the brain itself and its connections. Tbi: an alteration in brain function, or other evidence of brain pathology, caused by an external force. Brief period of confusion or loss of consciousness. Brain pathology: neuroimaging confirmation of brain damage: movement that causes brain to hit the inside of the skull, followed by a counterblow. Secondary insult onset may be hours to days after tbi induced by primary insult. Moderate and severe tbi patients must be put in the intensive care unit in order to recover from their injuries. This is the primary difference from mild tbi. Includes post-traumatic amnesia (pta), which is a state of confusion, agitation and disorientation.
