1/20/2024 0 Comments Causes of fixed dilated pupilNeurosurgeon, HEMS doctor, and all round good egg Mark Wilson was on the RAGE podcast recently and mentioned favourable outcomes from neurosurgery in patients with extradural (=epidural) haematomas who present with bilateral fixed dilated pupils (BFDP). Pupil involving third-nerve palsy should be investigated thoroughly and referred to a neurologist.Almost two-thirds of patients with extradural haematoma and bilateral fixed dilated pupils survived after surgery, with over half having a good outcome After the paralytic strabismus is treated, the ptosis can be corrected. In patients with partial third-nerve palsy, surgery depends on the extent of involvement of extraocular muscles. This may be combined with superior oblique (SO) tendon transposition, which causes a tonic adducting force to the globe to keep it in the primary position. Surgery for complete third-nerve palsy includes resection of the medial rectus and recession of the lateral rectus muscle for correction of horizontal deviation. ![]() Surgical options for TNP depend on the degree of the palsy: complete or partial. Before operating on the lid to correct ptosis, the eye should be aligned to prevent diplopia. Surgery for third-nerve palsy is nevertheless challenging, and the goals are to provide alignment of the eye in primary gaze and to provide binocular single vision. In pupil-sparing cases, surgical treatment is advised after 6 months in acquired palsies, if there is no improvement in symptoms. Botulinum toxin causes paralysis of the LR, and subsequently, the outward deviation of the eye is neutralized in the primary position. documented botulinum toxin injection in lateral rectus (LR) in the acute phase of partial third-nerve palsy. In pediatric cases, amblyopia due to ptosis or squint can be prevented by alternate patching. In cases of diplopia, the affected eye can be occluded with the help of an eye patch or opaque contact lens. Most patients with ischemic third-nerve palsy demonstrate improvement within 1 month and complete recovery in 3 months. Patients should be followed up every 3 months to check for signs of improvement. It is advocated as a short-term measure in acute palsy and for patients who are over 50 years of age having a history of diabetes or hypertension. This aberrant regeneration phenomenon can cause lid gaze dyskinesis or pupil-gaze dyskinesis. This is because of the endoneurial sheath which is damaged only by compression and trauma and not by vascular lesions. Aberrant regeneration of third-nerve may follow compressive or traumatic lesions but not vascular lesions like diabetes. This results in pupil-sparing third nerve palsy. On the other hand, medical lesion such as diabetes mellitus or hypertension microangiopathy will affect the vasa vasorum and thus spare the pupillary fibers. Lesions such as an aneurysm, uncal herniation, or tumor, which compress the nerve from outside will involve the superficial pupillomotor fibers and their blood supply. In contrast, the main trunk of the fibers is supplied by the vasa vasorum. The pial blood vessels supply these fibers. An interesting point to note is that before the 3 nerve reaches the orbit, the fibers innervating the pupillary muscles (pupillomotor fibers) are located superficially in the nerve trunk. ![]() In the orbit, the smaller superior division supplies the superior rectus and the levator palpebrae superioris, whereas the larger inferior division supplies the medial rectus, the inferior rectus, and the inferior oblique. The nerve then divides into a superior and inferior division and enters the orbit through the superior orbital fissure. During this course, the oculomotor nerve lies lateral to the posterior communicating artery. Accessory parasympathetic nucleus (Edinger-Westphal nucleus)Īs shown in the figure below, fibers pass through the interpeduncular fossa before passing between the posterior cerebral artery and the superior cerebellar artery to reach the cavernous sinus.
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