1. Which part of the nervous system controls the size of the pupils?
Autonomic nervous system (ANS).
1. The parasympathetic part of the ANS causes pupillary constriction via the GVE fibers in the oculomotor nerves (III).
2. The sympathetic part causes pupillary dilation via a convoluted pathway beginning in the hypothalamus and ending with postganglionic fibers from the superior cervical ganglion traveling in a perivascular plexus around the internal carotid artery (ICA plexus).
2. List two mechanisms that can cause asymmetry in the size of the pupils (anisocoria).
1. A lesion of the oculomotor nerve, causing pupillary dilation.
2. A lesion of the sympathetic pathways, causing pupillary constriction.
3. List two parts of the nervous system that control the resting state or tone of the upper eyelid.
1. The somatic efferent (SE) part of the oculomotor nerve (III) supplies the skeletal muscle component of the levator palpebrae superioris (LPS) muscle (the major component of the muscle).
2. The oculosympathetic fibers in the ICA plexus (as above) supply the smooth muscle component of the LPS muscle (a minor component of the LPS, sometimes called the superior tarsal muscle).
4. Of the above possibilities, what do you think was the cause of this patient's ptosis and miosis? Can these findings be more objectively evaluated? If so, how would you do that?
Involvement of the oculosympathetic fibers (i.e., oculosympathetic paresis). Yes. Pupillary drug testing with 1% hydroxyamphetamine (Paredrine) and Starch-Iodine Sweat Testing.
5. With the information presented, how precisely can the lesion be localized?
Not very precisely. The patient’s left periorbital/retro-orbital headache is nonlocalizing (also see below)
6. Indicate the specific structure(s) possibly involved by the pathologic process to produce this patient’s ptosis and miosis, including the side of involvement.
Involvement of the left-sided oculosympathetic pathways: including the lateral brain stem tegmentum, lateral funiculus of the cervical spinal cord, lateral horn of T1-3 spinal cord, T1-3 ventral roots, spinal nerves, white rami communicantes, T1-3 thoracic sympathetic trunk ganglia, cervical sympathetic trunk and/or the inferior, middle, or superior cervical sympathetic ganglia, ICA perivascular oculosympathetic plexus
7. How would you classify the headache in this case? This patient’s findings represent a specific neurologic syndrome. What is the name of that syndrome?
Vascular – Pericarotid (Raeder’s) Syndrome (Differential Dx: Tolosa-Hunt
syndrome, ICA dissection, ICA aneurysm, parasellar lesion)
8. In general, what type of pathologic process is involved in this case?
Perivascular inflammation
9. What diagnostic procedure(s) would you undertake at this point to try to further localize the lesion?
References:
1. Vijayan N, Watson C. Headache 1978;18:244-254.
2. Watson C, Vijayan N. Clinical Anatomy 1995;8:262-272.
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