It is interesting to see this present on the list. We were only discussing
it last week in the ED here.
Anisicoria in the setting of non-major head trauma with an alert interactive
patient has been an observation I have noted not infrequently in a specific
subset of patients, both adult and pediatric. The most frequent clinical
finding that has been common to these patients has related to the mechanism
of impact. The majority of patients had experienced a lateral rather than
primarily frontal impact to the head.
David Meany (a biomechanical engineer in Philadelphia) and others work,
support the vast differences in brain substance torque with respect to
impact direction. In the setting of an alert patient, I have not seen a
discussion of the pathophysiologic etiology of anisocoria, and particulalry
no discussion relating to impact direction. However the frequency with which
I have observed this clinical picture associated with a lateral impact
suggests that this may warrant a focussed study. It may be that there is a
more unilateral relative strain (or torque) on the CNS resulting in possibly
a self limiting partial 3rd nerve neuropraxia.
For the record, also in the setting of lateral head impact with a clear and
crisp sensorium, if the neuro assessment is sufficiently detailed, I have
also noted subtle transient cortical hemiparasthesias .
>---------- Forwarded message ----------
>Date: Wed, 24 Jun 1998 00:54:17 -0400
>From: Harvey Louzon <[log in to unmask]>
>To: Multiple recipients of list PED-EM-L <[log in to unmask]>
>Subject: Re: unilateral pupillary dilitation
>>>1) did anyone ever see / hear off / read about difference in
>> pupillary size with reactive pupils in an otherwise clinically normal
>> trauma victim, which signified uncal herniation or other serious
>> event ?<<
>Of course, you have to first distinguish cases of physiologic anisicoria.
>Generally this is limited to 0.5 mm differnce in pupil size but, more
>importantly, the pupillary inequality will be maintained as ambient
>lighting conditions change. E.g., relative anisicoria due to oculomotor
>nerve palsy will INCREASE in bright lighting conditions. Physiologic
>anisocoria will not.
>Other than direct trauma to the orbit affecting the ciliary ganglion
>(mydiasis) or dissection of a carotid artery causing an ipsilateral
>Horner's syndrome (miosis) I am unaware of any other mechanism, excepting
>3rd nerve compression, that can do this.
>It has been said, although I can provide no literature reference, that a
>3rd nerve palsy in a fully awake patient is NEVER caused by uncal
>herniation. I.e., by the time pupillary inequality occurs mentation will be
>invariably impaired (in some manner) due to the associated brainstem
>Now a *trochlear* nerve palsy characterized, of course, by diplopia in
>certain directions of gaze, has been described in blunt head injury. I
>have seen a case of this presenting several days later.
>For more information, send mail to [log in to unmask] with the
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Nadine Levick MBBS FACEM FRACGP
Division Pediatric Emergency Medicine
Johns Hopkins Medical Institution
600 North Wolfe Street / CMSC 144
Baltimore, MD 21287-3144
ph: 410 955 6143 / 6149
fax: 410 502 5440
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