Concussions and TBI After a Car Accident

The Bottom Line

Traumatic brain injuries are among the most serious and most underdiagnosed injuries from car accidents. A concussion is a "mild" TBI by medical classification, but there is nothing mild about months of headaches, memory problems, vestibular dysfunction, and cognitive fog that can follow. The biggest challenge with TBI claims in North Carolina is that standard imaging often looks normal even when the injury is real, giving insurance companies an opening to deny or minimize your claim. Early diagnosis, specialized evaluation, and thorough documentation are essential.

Understanding Concussions and Traumatic Brain Injuries

A traumatic brain injury (TBI) occurs when an external force disrupts the normal function of the brain. In a car accident, this can happen in two ways:

• Impact injury -- your head strikes the steering wheel, window, dashboard, headrest, or airbag
• Acceleration/deceleration injury -- the sudden change in speed causes your brain to shift and rotate inside the skull, bruising brain tissue against the inner walls of the skull

This second mechanism is critical to understand. You do not have to hit your head to sustain a brain injury. The violent forces in a car accident can cause a concussion purely through the rapid movement of the brain inside the skull. This is the same mechanism that causes concussions in football -- the brain moves faster than the skull can protect it.

When the brain impacts the inside of the skull, it causes bruising, swelling, and disruption of the neural connections that allow normal brain function. In more severe cases, blood vessels can tear, causing bleeding inside or around the brain.

The Glasgow Coma Scale: How TBI Severity Is Classified

Doctors use the Glasgow Coma Scale (GCS) to classify the initial severity of a traumatic brain injury. The GCS measures three things: eye opening, verbal response, and motor response. The total score ranges from 3 to 15.

The vast majority of car accident TBIs are classified as mild (GCS 13-15). This is where the label becomes dangerously misleading.

Why "Mild TBI" Is a Misleading Label

The word "mild" in "mild traumatic brain injury" refers to the initial severity classification, not the long-term impact on your life. This distinction is one of the most important things to understand about brain injuries.

A person with a "mild" TBI can experience:

• Persistent headaches that do not respond to over-the-counter medication
• Difficulty concentrating -- inability to focus at work, trouble reading, losing track of conversations
• Memory problems -- forgetting appointments, repeating questions, difficulty learning new information
• Cognitive fatigue -- becoming mentally exhausted much faster than before the injury
• Personality changes -- increased irritability, emotional outbursts, depression, anxiety
• Sensitivity to light and noise -- making normal environments overwhelming
• Sleep disturbances -- insomnia, excessive sleepiness, or disrupted sleep patterns
• Dizziness and balance problems -- unsteadiness, vertigo, difficulty with coordination

These symptoms can persist for weeks, months, or in some cases permanently. There is nothing "mild" about being unable to perform your job, remember conversations, or regulate your emotions.

Delayed Symptoms: The Hidden Danger of Brain Injuries

Like whiplash, traumatic brain injuries frequently have delayed symptoms. You may feel dazed or confused at the scene of the accident, but the full range of symptoms may not develop for hours or days.

Common timeline for TBI symptom onset:

• Immediate -- confusion, disorientation, brief loss of consciousness, headache
• Hours after the accident -- worsening headache, nausea, dizziness, difficulty remembering the accident
• 24 to 72 hours -- sensitivity to light and noise, sleep problems, irritability, difficulty concentrating
• Days to weeks -- cognitive difficulties become more apparent, memory problems emerge in daily life, mood changes develop
• Weeks to months -- if symptoms persist beyond 4 weeks, post-concussion syndrome may be developing

Post-Concussion Syndrome

Post-concussion syndrome is a significant complication because it extends the duration and impact of the injury far beyond what insurance companies expect for a "mild" TBI. It can prevent you from working, caring for your family, and living your normal life for an extended period.

The Imaging Problem: Why CT Scans and MRIs Miss Concussions

One of the biggest challenges with mild TBI claims is the limitation of standard medical imaging.

CT Scans

A CT scan is typically the first imaging study ordered after a head injury. CT scans are excellent at detecting skull fractures, brain bleeding, and large areas of swelling -- the life-threatening complications of a brain injury. However, CT scans cannot detect concussions. The microscopic damage to neural connections that causes concussion symptoms is far too small to appear on a CT.

This means that in the vast majority of car accident concussions, the CT scan comes back "normal." The insurance company will later use this result to argue: "The CT was negative, so there is no brain injury."

Standard MRI

A standard MRI is more detailed than a CT scan and can detect smaller abnormalities. However, like CT scans, standard MRI sequences often appear normal in mild TBI cases. The damage occurs at a microscopic level -- in the axons (nerve fibers) that connect different parts of the brain -- and standard MRI sequences are not sensitive enough to detect it.

Advanced Imaging (When Standard Tests Fail)

Newer imaging technologies are better at detecting the subtle damage caused by concussions:

• Diffusion Tensor Imaging (DTI) -- a specialized MRI technique that maps the white matter tracts (nerve fiber bundles) in the brain and can detect damage to these connections
• Susceptibility Weighted Imaging (SWI) -- an MRI technique that can detect tiny areas of bleeding (microhemorrhages) not visible on standard scans
• Functional MRI (fMRI) -- measures brain activity patterns and can show altered function in brain regions affected by the injury

These advanced imaging studies are not routinely ordered in emergency rooms, but they can be obtained through a neurologist or neuropsychologist and can provide objective evidence of brain injury when standard tests appear normal.

Vestibular Dysfunction: The Frequently Missed TBI Complication

The vestibular system -- the inner ear structures and brain pathways that control balance and spatial orientation -- is particularly vulnerable to traumatic brain injury. Post-traumatic vestibular dysfunction affects an estimated 30 to 65 percent of TBI patients, yet it is frequently missed in the initial emergency room evaluation and is rarely discussed in injury claims.

What Post-Traumatic Vestibular Disorders Look Like

The most common post-traumatic vestibular condition is benign paroxysmal positional vertigo (BPPV) -- calcium crystals in the inner ear become dislodged during impact and trigger intense spinning sensations when the head changes position. Other presentations include:

• Labyrinthine concussion -- direct trauma to the inner ear causing persistent dizziness, balance instability, and hearing sensitivity
• Perilymphatic fistula -- a tear in the membrane between fluid compartments of the inner ear, causing dizziness that worsens with physical exertion or pressure changes
• Central vestibular dysfunction -- damage to brain pathways in the brainstem, cerebellum, or cortex that process balance signals, causing chronic imbalance and motion sensitivity

Symptoms can include intense spinning sensations (vertigo), constant unsteadiness, inability to tolerate visually busy environments, motion sickness that did not exist before the accident, and difficulty walking on uneven surfaces.

How Vestibular Dysfunction Is Diagnosed and Documented

Standard diagnostic testing produces objective, quantifiable findings:

• Dix-Hallpike maneuver -- the bedside test used to diagnose BPPV; a positive finding is documented clinical evidence
• Videonystagmography (VNG) -- records involuntary eye movements caused by vestibular stimulation, providing objective measurement of vestibular function
• Rotary chair testing -- assesses how well both vestibular systems coordinate
• Computerized dynamic posturography -- measures balance control under different sensory conditions with quantitative output

These tests produce data-driven measurements that are far more defensible in an insurance claim than self-reported dizziness alone. A positive VNG or posturography result is objective evidence of vestibular damage.

Vestibular Rehabilitation Therapy

Treatment for post-traumatic vestibular dysfunction is specialized physical therapy called vestibular rehabilitation therapy (VRT). Standard physical therapists are not trained in VRT -- you need a vestibular-certified PT. VRT uses:

• Canalith repositioning maneuvers (the Epley maneuver) to move dislodged ear crystals back into proper position
• Gaze stabilization exercises to train the brain to compensate for impaired vestibular input
• Balance retraining to reduce fall risk and restore functional mobility
• Habituation exercises to desensitize the brain to motion stimuli that trigger vertigo

VRT treatment records document measured deficits and measurable progress at every session -- exactly the kind of objective evidence insurance companies claim does not exist for TBI cases.

Sleep Disruption After Traumatic Brain Injury

Sleep disorders are among the most common and most disabling consequences of TBI, affecting an estimated 30 to 70 percent of patients. They are rarely diagnosed because emergency rooms do not evaluate sleep, and patients often do not connect disrupted sleep to their brain injury. Yet they significantly compound every other TBI symptom -- poor sleep makes memory problems, attention deficits, and mood disturbances dramatically worse.

TBI damages the brain structures that regulate sleep -- the hypothalamus, thalamus, and brainstem -- directly disrupting the normal sleep-wake cycle.

Types of Post-Traumatic Sleep Disorders

• Post-traumatic hypersomnia -- excessive daytime sleepiness, difficulty staying awake, sleeping 10 to 14 hours but still feeling unrefreshed. The most common sleep disorder after TBI.
• Insomnia -- difficulty falling asleep, staying asleep, or achieving restorative sleep, often combined with hyperarousal
• Circadian rhythm disruption -- the biological clock is disrupted, causing reversed sleep-wake cycles or extreme difficulty with normal daily schedules
• Sleep apnea exacerbation -- TBI can worsen or trigger obstructive sleep apnea through its effects on upper airway muscle tone and brainstem respiratory control

Why Sleep Disorders Matter for Your Claim

Post-traumatic sleep disorders are documented, diagnosed conditions that add measurable value to a TBI claim. Polysomnography (an overnight sleep study) provides objective, quantitative documentation of sleep architecture abnormalities. The Epworth Sleepiness Scale is a validated, standardized tool for measuring daytime sleepiness. Both create a paper trail that is far more defensible than self-reported fatigue.

If you are experiencing sleep disruption after a car accident involving a head injury, ask your neurologist or primary care doctor for a sleep medicine referral. A sleep disorder diagnosis adds a separate, documented injury to your claim record and gives your treatment team a fuller picture of how the accident has affected your neurological function.

Long-Term Cognitive Effects of TBI

While most concussions resolve fully, some people experience lasting cognitive effects that change their ability to function normally. These long-term effects are more common with moderate to severe TBI, but they can also occur with mild TBI, especially with repeated concussions or prolonged post-concussion syndrome.

Potential long-term effects include:

• Persistent memory problems -- difficulty retaining new information, forgetting recent events, needing written reminders for tasks that used to be automatic
• Reduced processing speed -- taking longer to understand information, respond to questions, or complete mental tasks
• Executive function deficits -- difficulty planning, organizing, multitasking, problem-solving, and making decisions
• Attention and concentration problems -- inability to maintain focus, easy distractibility, difficulty following complex conversations
• Personality and behavioral changes -- increased impulsivity, reduced emotional control, social inappropriateness
• Increased risk of depression and anxiety -- brain injury can alter brain chemistry and increase vulnerability to mental health conditions

These effects can be devastating to a person's career, relationships, and independence. A lawyer who could no longer process complex legal arguments, a teacher who could not manage a classroom, or a parent who could not keep track of their children's schedules -- these are real and catastrophic losses that deserve real compensation. TBI is especially common in motorcycle accidents, where the lack of vehicle structure around the rider means the head is far more exposed to impact forces.

Occupational Therapy and Cognitive Rehabilitation

Occupational therapists (OTs) and cognitive rehabilitation specialists play a critical but frequently overlooked role in TBI recovery. Their records are also valuable evidence for your claim.

What Occupational Therapists Do After TBI

An OT evaluates how your TBI affects your activities of daily living -- cooking, driving, managing finances, caring for children, and performing job duties. For TBI patients, occupational therapy focuses on:

• Cognitive strategy training -- compensatory techniques to manage memory problems, attention deficits, and organizational difficulties
• Activities of daily living (ADL) retraining -- rebuilding the ability to perform everyday tasks that the injury has impaired
• Environmental modifications -- recommending changes at home and work to reduce cognitive load and prevent errors
• Adaptive equipment -- tools like reminder systems, organizational aids, and task management strategies to compensate for impaired cognitive function
• Return-to-work assessments -- formal evaluation of your functional capacity in a work environment

Cognitive Rehabilitation Therapy

Cognitive rehabilitation therapy (CRT) is a structured, goal-directed treatment program designed to rebuild specific cognitive functions impaired by TBI -- attention, memory, processing speed, executive function, and problem-solving. CRT is delivered by neuropsychologists, occupational therapists with cognitive rehabilitation training, and speech-language pathologists.

OT evaluation reports and CRT progress notes document exactly which cognitive functions are impaired and to what degree -- the precise "objective evidence" that insurance companies claim does not exist for mild TBI. For information about speech therapy for TBI communication disorders, see our guide on speech therapy after TBI.

Returning to Work After TBI: ADA and FMLA Protections

TBI can make it impossible to perform your job at the same level or on the same schedule as before the accident. Two federal laws protect you during recovery.

Americans with Disabilities Act (ADA) Title I

Cognitive impairments from TBI -- memory deficits, attention problems, and processing speed reductions -- can qualify as disabilities under ADA Title I if they substantially limit a major life activity. Employers with 15 or more employees must provide reasonable accommodations for employees with qualifying disabilities. Common TBI accommodations include:

• Extended time to complete tasks and deadlines
• Written instructions instead of verbal directions
• Quiet workspace to minimize distraction
• Modified work schedule or reduced hours during recovery
• Permission to record meetings to compensate for memory deficits
• Postponement of performance evaluations during the acute recovery period

The employer's obligation is to engage in an interactive process with you -- a dialogue about what accommodations would let you perform your essential job functions. They cannot simply terminate you because you have become temporarily less efficient.

Family and Medical Leave Act (FMLA)

If you work for an employer with 50 or more employees and have worked there for at least 12 months, FMLA provides 12 weeks of job-protected leave per year for a serious health condition. A TBI requiring inpatient care or continuing treatment qualifies. This leave can be taken intermittently for doctor's appointments, therapy sessions, or days when symptoms are severe.

For a complete overview of how lost wages and earning capacity are calculated after TBI -- including the vocational expert and life care planner roles -- see our guide on vocational rehabilitation after a car accident.

How TBI Severity Drives Claim Value in NC

The value of a TBI claim in North Carolina is primarily driven by the severity and duration of the injury, the quality of your medical documentation, and the impact on your ability to work and live your life.

Mild TBI (Concussion) That Resolves

A concussion that resolves within 2 to 4 weeks with no lasting effects will have a lower claim value. However, even a resolving concussion involves medical costs, missed work, and a period of real suffering.

Typical NC settlement range: $15,000 to $75,000

Mild TBI with Post-Concussion Syndrome

When concussion symptoms persist for months, the claim value increases substantially. Post-concussion syndrome involves ongoing medical treatment, extended lost wages, and a significant impact on quality of life.

Typical NC settlement range: $75,000 to $300,000

Moderate TBI

A moderate TBI with documented loss of consciousness and lasting cognitive deficits significantly increases claim value. These cases often involve months of rehabilitation, job modifications or job loss, and permanent changes to cognitive function.

Typical NC settlement range: $200,000 to $750,000+

Severe TBI

Severe TBIs with extended loss of consciousness, significant brain damage, and permanent disability result in the highest claim values. These cases account for lifetime medical care, complete loss of earning capacity, and profound loss of quality of life. For a detailed breakdown of future damages calculation in catastrophic TBI cases -- including life care plans and forensic economist testimony -- see our guide on future damages calculation in NC.

Typical NC settlement range: $500,000 to several million dollars

NC Statute of Limitations Tolling for TBI Victims

North Carolina imposes a 3-year statute of limitations on personal injury claims under N.C. Gen. Stat. § 1-52(16). Miss this deadline and your claim is permanently barred, regardless of its merits. For most TBI victims, the 3-year clock begins on the date of the accident -- but there is an important exception for victims who lacked capacity.

This tolling provision matters most for victims with severe TBI who were unconscious after the accident, those with significant cognitive impairment that prevented understanding of legal rights, and cases where a family member managing the victim's affairs may not realize a filing deadline is running.

Challenges of Proving Mild TBI to Insurance Companies

Mild TBI claims are among the hardest car accident injury claims to prove. Insurance companies exploit several vulnerabilities.

"The CT scan was normal." This is the most common argument. The adjuster will point to a negative CT scan as proof that there is no brain injury. As explained above, CT scans are not designed to detect concussions -- they detect bleeding and fractures. A normal CT does not mean a normal brain.

"You were not unconscious." Many people believe a concussion requires loss of consciousness. It does not. You can sustain a concussion with only a brief period of confusion or disorientation. The insurance company will argue: "There was no loss of consciousness, so there was no brain injury."

"Your symptoms are from stress or depression." The adjuster may attribute your cognitive difficulties, mood changes, and fatigue to emotional stress or a pre-existing mental health condition rather than a brain injury. This is why having a neurologist or neuropsychologist connect your symptoms to the accident is so important.

"You should have recovered by now." Insurance companies will cite the 2-to-4-week average recovery timeline for concussions and argue that any symptoms beyond that point are unrelated to the accident. This ignores the well-documented reality of post-concussion syndrome.

"There is no objective evidence." Without abnormal imaging, the adjuster will argue that your symptoms are self-reported and unverifiable. Neuropsychological testing, vestibular testing, and polysomnography each produce the objective, measurable evidence needed to counter this argument.

Second Impact Syndrome: Why Full Recovery Before Return to Activity Is Non-Negotiable

Second impact syndrome is rare but is almost universally catastrophic when it occurs. From a legal standpoint, if you sustain a second head injury after failing to follow a doctor's return-to-activity protocol, the at-fault driver's insurer may argue that the second injury is your own fault under NC's contributory negligence rule. Following and documenting your doctor's return-to-activity clearance process protects both your health and your claim.

Protecting Your TBI Claim in NC

1. 1

   Go to the emergency room immediately

   Even if you feel dazed rather than severely injured, get evaluated. Tell the ER doctor about the accident and describe every symptom -- headache, confusion, dizziness, nausea, sensitivity to light or noise, difficulty concentrating, and memory problems about the accident itself. A documented ER visit that records your symptoms is the foundation of your TBI claim.

2. 2

   Follow up with a neurologist within 1 to 2 weeks if symptoms persist

   The ER's job is to rule out life-threatening conditions, not to diagnose and treat concussions. If you have any cognitive symptoms, headaches, dizziness, or sleep disruption at your one-week follow-up, ask your primary care doctor for a neurology referral. Neurologists are the appropriate specialists to diagnose and document post-concussion syndrome.

3. 3

   Request neuropsychological testing for cognitive symptoms

   If you are experiencing memory problems, attention deficits, difficulty with processing speed, or executive function issues, ask for a referral to a neuropsychologist for formal testing. This 4-to-8-hour battery of standardized tests produces objective, quantitative documentation of cognitive impairment that insurance companies cannot dismiss as subjective.

4. 4

   Ask about advanced imaging if standard CT and MRI are normal

   If standard imaging appears normal but your symptoms persist, ask your neurologist about Diffusion Tensor Imaging (DTI) and Susceptibility Weighted Imaging (SWI) -- specialized MRI techniques that can detect microscopic white matter damage and microhemorrhages that standard sequences miss.

5. 5

   Get a vestibular evaluation if you have dizziness or balance problems

   Ask for a referral to a vestibular-certified physical therapist for VNG testing if you are experiencing dizziness, vertigo, or balance instability. Vestibular testing produces objective measurements that document a commonly missed TBI complication. This is a separate referral from standard physical therapy.

6. 6

   See a sleep medicine specialist if you have sleep disruption

   If you are sleeping excessively, unable to sleep, or waking unrefreshed, ask for a sleep medicine referral. A polysomnography (sleep study) documents post-traumatic sleep disorders as a separate, diagnosed condition -- adding measurable value to your claim and guiding your treatment.

7. 7

   Keep a detailed daily symptom journal

   Record headaches, memory lapses, concentration failures, sleep quality, mood changes, dizziness episodes, and how each symptom affected your ability to work, care for your family, or complete daily tasks. A journal creates a contemporaneous record that is much harder for an adjuster to dispute than symptoms recalled months later.

8. 8

   Do not minimize your symptoms to any medical provider

   Be thorough and honest about every symptom at every appointment. Doctors document what you report. An offhand 'I'm doing a little better' will appear in the record and can be taken out of context to argue you have recovered. Report all ongoing symptoms even when some have improved.

9. 9

   Do not return to activities that risk a second head impact until cleared

   Second impact syndrome -- a second concussion before the first has healed -- can be fatal or permanently disabling. Follow your doctor's return-to-activity protocol and document the clearance in your medical records. Returning too early also creates a contributory negligence argument in NC if a subsequent injury occurs.

10. 10

    Consider hiring a lawyer

    TBI cases are among the most complex personal injury claims. They require expert testimony from neurologists, neuropsychologists, and potentially life care planners and forensic economists. The stakes are high enough -- from $75,000 for PCS to several million for severe TBI -- that professional representation is almost always worth it. See our guide on when to hire a lawyer for help deciding.

Frequently Asked Questions

Frequently Asked Questions

What is the difference between a concussion and a traumatic brain injury?▾

A concussion is a type of traumatic brain injury. All concussions are TBIs, but not all TBIs are concussions. Concussions are classified as "mild" TBIs on the Glasgow Coma Scale (GCS 13-15), while moderate TBIs (GCS 9-12) and severe TBIs (GCS 3-8) involve more significant brain damage. The term "mild" refers to the initial severity classification, not the impact on your life -- even mild TBIs can cause debilitating symptoms lasting months or years.

Can you get a concussion in a car accident without hitting your head?▾

Yes. A concussion does not require a direct blow to the head. The rapid acceleration and deceleration forces in a car accident can cause the brain to shift inside the skull, bruising brain tissue even without any head impact. This is why concussions are common in rear-end collisions and other crashes where the head whips forward and backward violently.

What are the signs of a concussion after a car accident?▾

Common signs include headache, dizziness, confusion, memory problems (especially about the accident itself), nausea, sensitivity to light or noise, blurred vision, difficulty concentrating, fatigue, irritability, and sleep disturbances. Symptoms can appear immediately or develop over hours to days after the accident. Any suspected concussion should be evaluated by a doctor promptly.

How long do concussion symptoms last after a car accident?▾

Most concussion symptoms resolve within 2 to 4 weeks. However, 15% to 30% of concussion patients develop post-concussion syndrome, where symptoms persist for months or even longer than a year. Symptoms like headaches, difficulty concentrating, memory problems, and mood changes can significantly affect your ability to work and function normally during this extended recovery period.

Why is it hard to prove a mild TBI to an insurance company?▾

Mild TBIs often do not show abnormalities on CT scans or standard MRIs, which are the imaging tools used in most emergency room evaluations. Insurance companies rely on this lack of imaging evidence to argue the injury does not exist or is not serious. They will point to a "normal" CT scan and claim you are fine, even though CT scans are designed to detect bleeding and fractures, not the microscopic damage that causes concussion symptoms.

How much is a traumatic brain injury claim worth in North Carolina?▾

TBI claim values in NC vary enormously based on severity. A mild TBI or concussion that resolves within weeks may settle for $15,000 to $75,000. A mild TBI with persistent post-concussion syndrome may settle for $75,000 to $300,000. Moderate to severe TBIs with lasting cognitive impairment can result in settlements or verdicts of $500,000 to several million dollars. NC does not cap compensatory damages, so there is no artificial limit on recovery.

What is vestibular therapy and how does it help after a TBI?▾

Vestibular rehabilitation therapy (VRT) is a specialized form of physical therapy performed by vestibular-certified PTs that treats balance and dizziness disorders caused by TBI. Standard PTs are not trained in VRT. Treatment includes canalith repositioning maneuvers for BPPV, gaze stabilization exercises, and balance retraining. VRT records also provide objective, measurable documentation of vestibular impairment -- exactly the kind of evidence insurance companies claim does not exist for brain injury cases.

What is second impact syndrome and why does it matter after a car accident concussion?▾

Second impact syndrome occurs when a second concussion is sustained before the first has fully healed. The brain is in a vulnerable state of impaired autoregulation and cannot control swelling. A second impact -- even a minor one -- can cause rapid, diffuse cerebral swelling that is frequently fatal or permanently disabling. You must not return to any activity that risks head impact until a doctor has cleared you from the first concussion.

Can NC's statute of limitations be extended for TBI victims?▾

Yes. Under N.C. Gen. Stat. § 1-17, the statute of limitations is tolled (paused) during any period when a person lacks the capacity to manage their own legal affairs due to a disabling condition. For severe TBI victims who were unconscious or cognitively incapacitated, the 3-year clock may not begin running until capacity is restored. However, tolling is fact-specific and contested -- do not assume it applies automatically. Consult an attorney immediately about your specific deadlines.

Can I get ADA accommodations for brain injury symptoms at work?▾

Possibly. Cognitive impairments from TBI -- memory deficits, attention problems, processing speed reductions -- can qualify as disabilities under ADA Title I if they substantially limit a major life activity. Employers with 15 or more employees must provide reasonable accommodations such as extended task deadlines, written instructions, quiet workspace, modified schedules, and permission to record meetings. The employer must engage in an interactive process with you about what accommodations would let you perform your essential job functions.