What is a Pre-Existing Condition?

Key Legal Principles — “Eggshell Plaintiff” and “Crumbling Skull”

The “Eggshell Plaintiff” Rule

Also called the “thin skull” rule, this doctrine holds that a defendant must take the plaintiff as they find them. If you had a vulnerability or pre‑existing condition that made your injury worse, the defendant cannot escape responsibility just because you were more susceptible than a “healthy” person.

The “Crumbling Skull” Concept

Less familiar, but important: this concept applies when a plaintiff had a condition that was already deteriorating (i.e., the crumbling skull). In that case, the defendant is responsible only for the additional harm or acceleration of deterioration caused by the incident — not for the part the condition would have deteriorated anyway.

As your attorneys at The Jewkes Firm, our job is to help determine how these doctrines apply in your case:

• Did the accident merely hit an already collapsing condition?
• Or did it meaningfully accelerate or worsen your injury beyond what would have happened anyway?

Common Examples of Pre‑Existing Conditions in Personal Injury Cases

Here are some typical examples of pre‑existing conditions that arise in our practice:

• Degenerative disc disease or prior back/neck injuries
• Previous fractures, surgeries or prior trauma in the same body area
• Arthritis, osteoporosis or other chronic musculoskeletal conditions
• Mental health conditions (depression, anxiety, PTSD) aggravated by the accident
• Pre‑existing pain or mobility limitations you had before the acciden.

In each of these settings, the questions are:

• What changed because of the accident?
• Did you now require more treatment, more pain, lost more work, have less function than you would have had absent the accident?

How Pre‑Existing Conditions Are Treated in a Claim

When a claim involves a pre‑existing condition, the case often becomes more complex: the medical history needs to be carefully parsed, causation must be clearly shown, and insurance defense tactics must be countered. That’s precisely where The Jewkes Firm brings value:

Documenting Your Medical History

To establish a baseline and to differentiate old from new or worsened injuries, clear medical records are crucial. These may include:

• Your medical history before the incident (doctor visits, treatments, imaging, medications).
• Evidence of your condition immediately following the accident (ER visits, new imaging, new symptoms).
• Treatment trajectory after the accident showing changes or worsening of your condition.
• Expert medical testimony linking the accident to the aggravation or new injury.

Proving Aggravation or New Injury

Because insurance companies often argue “this pain is from your old injury, not the crash”, we focus on establishing causation: that the incident materially worsened your condition or caused new harm. This may require comparing your pre‑accident condition with your post‑accident condition, showing changed symptoms, increased treatment, decreased function or worse prognosis.

Overcoming Insurance Tactics

Insurance adjusters may attempt to:

• Blame your prior condition entirely for your problems.
• Argue that nothing materially changed due to the incident.
• Offer a lower settlement by reducing your damages because of your prior condition.

Here at The Jewkes Firm, we anticipate these tactics and build the medical, factual and legal foundation to address them decisively.

Calculating Damages

If you had a pre‑existing condition but the accident made it worse, you may recover for:

• Additional medical treatment and future care required because of the worsening.
• Increased pain and suffering due to the aggravated condition.
• Lost income or diminished earning capacity stemming from the aggravated condition.
• Loss of enjoyment of life, functional limitations, and other non‑economic harms.

It’s critical to isolate what you would have expected absent the accident (the baseline) from what the accident added. That way your compensation reflects only the incremental harm caused by the responsible party.