POST HOC

..ergo Propter Hoc. A classic fallacy.

As documented in Medical Litigation News Volume 2, Issue 5, de novo onset of bowel symptoms for no evident reason is so common that it is inevitable the change will sometimes coincide with recent occurrence of a physical injury. Given that a pathological mechanism is plausible, a compassionate physician may readily agree to make a spurious Causal connection.

Patients and clients cannot be relied on to provide an accurate narrative of the sequence of events. Revisionist memory is a universal human foible. Without conscious intent to distort, we edit our recall of distant past events to fit our beliefs and wishes.

 

PRACTICE POINT 

Attribution of chronic symptoms usually requires review of pre-injury medical records

Examination of not only the contemporaneous but also the pre-accident clinical records is essential for meaningful expert medical opinion. Thus, headaches following Mild Traumatic Brain Injury or Cervical Whiplash might be diagnosed as Post-Traumatic Migraine, whereas careful review including the previous general practitioner's pre-accident records may show that more accurate diagnosis would be short-lived Acute Post-Traumatic Headache disorder and/or temporary increase in the frequency of pre-existing Migraine.

The dispassionate legal medicine expert is uniquely placed to critique specialist opinions on Medical Causation. Not even the primary care physician has the opportunity and the motivation to collate and integrate all the details of multiple clinical assessments.

 

PRACTICE POINT

Causation of chronic diseases  

  1. strong correlation/high relative risk 
  2. dose-response relationship 
  3. consistent finding 
  4. biological plausibility 
  5. temporal cogency 
  6. control of confounding and bias 
  7. specificity 
  8. overall coherence 

Clinical attribution of Causation combines deduction from the commonly-accepted general causes[1] of a medical condition, and inductive reasoning[2], often based more on the reported facts than on objective criteria.

A recent paper[3] summarises the tests of general Causation: occurrence at least twice as frequently in injured subjects is considered strong evidence; risk of the disease should increase with duration and intensity of injury; research should be replicable with different study methods; the causal connection should make sense, based on current biological concepts, including time relationships; research must guard against bias in the selection of subjects, and must control for confounding variables; the association should be specific; finally, there should be coherence between the individual pieces of evidence.

Clinical medicine is not much concerned with individual Causation[4]. Expert attribution of chronic symptoms after soft-tissue injury is frequently based on little more than, "s/he tells me the symptoms began for the first time after the accident..."

Even when all or most of the general criteria of causation are fulfilled, injury may be only one of a number of factors which increase the probability of the occurrence of the disease in a given individual. Within the cluster[5] of causal factors, any item may be neither sufficient nor necessary.

 

PRACTICE POINT 

Beyond "crumbling skull": the injury may be a NON-ESSENTIAL factor which pushes above threshhold the probability that the chronic disease or symptoms will occur

The rear-ending Motor Vehicle Accident after which new symptoms lead to the discovery of Degenerative Disc Disease may be considered to have advanced the progression of the disease by an indeterminate period of months or years. The nature of the Disease is such that there may be no physical injury to the spine, but a temporarily sedentary lifestyle during recovery from soft-tissue injuries has simply unmasked the problem.

 

PRACTICE POINT 

The role of injury in the evolution of many overt or covert chronic diseases is speculative at best

Copyright 2008 Electronic Handbook of Legal Medicine