Journal of the Egyptian Ophthalmological Society

: 2013  |  Volume : 106  |  Issue : 3  |  Page : 150--152

Misdirection (aberrant regeneration) of the third cranial nerve

Sayed A Sayed, Mahmoud Rabea 
 Department of Ophthalmology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt

Correspondence Address:
Sayed A Sayed
Ophthalmology), Aaldrrasa, Alhussin Hospital, Ophthalmic Department, 4th Floor, Cairo


Purpose Head trauma can lead to aberrant regeneration of the third cranial nerve (oculomotor nerve). Background Aberrant regeneration of the third cranial nerve is most commonly due to its damage by trauma. Case report We report here the case of a patient who, following severe head injury, suffered from diplopia, abnormal deviation of the right eye (exotropia, moderate limitation in elevation and adduction), and overaction of the left lateral rectus. Neither ptosis nor limitation of sursumduction was seen in the right eye. Surgery was carried out for relieving diplopia due to aberrant regeneration of the third cranial nerve affecting the right eye. Right medial rectus resection (7 mm) and left lateral rectus recession (9 mm) were performed. Diplopia disappeared in the sixth week after operation. Conclusion Traumatic third nerve palsy may result in aberrant regeneration of the third cranial nerve. The full-blown features of this syndrome may or may not be present. Diplopia was relieved by performing surgery in both the affected eye (right medial rectus resection) and the healthy eye (left lateral rectus muscle recession).

How to cite this article:
Sayed SA, Rabea M. Misdirection (aberrant regeneration) of the third cranial nerve.J Egypt Ophthalmol Soc 2013;106:150-152

How to cite this URL:
Sayed SA, Rabea M. Misdirection (aberrant regeneration) of the third cranial nerve. J Egypt Ophthalmol Soc [serial online] 2013 [cited 2023 Jan 28 ];106:150-152
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The third cranial nerve, or oculomotor nerve, supplies most of the extraocular muscles, including the inferior oblique, the medial, superior, and inferior recti, and the levator muscle of the upper eyelid. It is responsible for ocular motility in the horizontal, vertical, and torsional planes and for levator function. In addition, the oculomotor nerve carries the parasympathetic fibers to the smooth muscles of the papillary sphincter and ciliary muscle [1]. The congenital and acquired forms of oculomotor nerve palsy may be partial (one or more muscles affected) or complete (papillary function also affected) [2]. Aberrant regeneration of cranial nerve III, otherwise known as oculomotor synkinesis, is an uncommon but well-described phenomenon most frequently resulting from trauma, tumors, and aneurysm of the posterior communicating artery (PCoA) [3],[4]. Its appearance usually follows an oculomotor palsy, but it can also occur primarily without any preceding nerve dysfunction. It is vital that neurosurgeons recognize this disorder because it may be the only sign of an underlying cavernous tumor or PCoA aneurysm.

The tumor most often implicated is a cavernous or parasellar meningioma, but any tumor that causes compression or disruption along the course of the oculomotor nerve may cause primary or secondary misdirection [1]. The most common clinical signs of oculomotor synkinesis consist of elevation of the upper eyelid on attempted downward gaze or adduction, adduction of the eye on attempted upward or downward gaze, and constriction of the pupil on attempted adduction 4. The full-blown features include horizontal gaze-eyelid synkinesis, pseudo-Graefe's sign, limitation of elevation and depression of the eye with retraction of the globe on attempted vertical movements, adduction of the involved eye on attempted elevation or depression, a pseudo-Argyll Robertson pupil, and absent vertical optokinetic response [5],[6],[7]. Although papillary constriction may occur in any direction of gaze requiring third nerve function, a pseudo-Argyll Robertson pupil is seen most often with adduction. This resembles an Argyll Robertson pupil, as it is nonreactive to light but constricts with convergence. These changes are due to reinnervation of the postganglionic fibers serving sphincter function by collaterals from adjacent fibers not originally innervating the sphincter [8].

 Case report

A 20-year-old male patient had a history of severe head injury of 8 months' duration. The patient was admitted to the ICU for 2 weeks. The cornea was clear in both eyes. Depth of the anterior chamber and color and pattern of the iris were normal in both eyes. The superior oblique (cranial nerve IV) and lateral rectus (cranial nerve VI) muscles were normal. There was no ptosis on primary gaze in the right eye. Prominent signs of aberrant regeneration were present in the right third nerve. The right eye showed moderate limitation of adduction and sursumduction. There was an elevation of the right upper eyelid on attempted adduction (oculomotor synkinesis). The pupil was normal (round, regular, and reacting) in the right eye (i.e. there was no Pseudo-Argyll Robertson pupil). In addition, there was no pseudo-Graefe's sign. Here, extraocular motility was full in all gazes in the left eye. There was an overaction of the left lateral rectus. Fundus examination was normal in both eyes.

Magnetic resonance angiography was performed to rule out aneurysms, and it showed normal PCoA. It was diagnosed as post-traumatic aberrant regeneration of the right third cranial nerve with palsy.


Aberrant regeneration of the third nerve was first described by Gowers [9]. This condition was caused by misdirected regenerating third nerve fibers to anomalous connections [10],[11]. Ocular electromyography has demonstrated the cocontraction of extraocular muscles innervated by the oculomotor nerve with aberrant regeneration [12]. In a case report, third nerve palsy resulting in 'misdirection' was due to trauma [3],[6]. The abnormal eyelid movements are due to cocontraction of muscles innervated by the third nerve. The regenerating fibers no longer follow their previous paths but innervate different muscles supplied by the third nerve [13]. The incidence of aberrant regeneration of the third nerve after acute third nerve injury is 15% [8]. Aberrant regeneration of the third cranial nerve should be kept in mind as a possible late complication in patients who suffer from severe head injury involving the third nerve. Patients should be warned about the possibility of nerve fiber misdirection and the potential problems caused by it. Follow-up should be carried out in consultation with ophthalmologists [4]. Our patient developed aberrant regeneration of the right oculomotor nerve after traumatic brain injury. Our aim was to correct diplopia in the primary position, which was mainly because of right medial rectus weakness.


After recession-resection, the eye was straight within 10 prism diopters of exotropia. Diplopia in the primary position was relieved in the sixth postoperative week.


Aberrant regeneration of the third nerve may occur after third nerve damage from traumatic head injury. The full-blown features of this syndrome may or may not be present. If diplopia is present following aberrant regeneration of the third nerve, one should correct it [Figure 1],[Figure 2],[Figure 3] and [Figure 4].{Figure 1}{Figure 2}{Figure 3}{Figure 4}[14]


Conflicts of interest

There are no conflicts of interest.


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