Original Article. A 3 Year Review of Cranial Nerve Palsies from the University of Port Harcourt Teaching Hospital Eye Clinic, Nigeria

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1 Original Article A 3 Year Review of Cranial Nerve Palsies from the University of Port Harcourt Teaching Hospital Eye Clinic, Nigeria Chinyere Nnenne Pedro Egbe, Bassey Fiebai, Elizabeth Akon Awoyesuku ABSTRACT Purpose: To provide the types, frequency and clinical information on common cranial nerve palsies seen at the Eye Clinic at the University of Port Harcourt Teaching Hospital. Materials and Methods: A chart review was performed of patients who presented with cranial nerve palsy at the Eye Clinic over a 3 year period (January 2009 December 2011). Data were collected on age, sex, type of cranial nerve palsy, a history of systemic disease such as diabetes mellitus (DM), hypertension and cerebrovascular disease. Exclusion criteria included medical charts with incomplete data. Data was analyzed using Epi info Version 6.04D. Statistical significance was indicated by P < Results: Twenty four patients had cranial nerve palsies. There were 11 males and 13 females with a mean age of ± years. Four patients (26.6%) had exotropia while three patients (20%) had esotropia. Complete ophthalmoplegia was noted in two patients (13.3%). The 3 rd and 6 th cranial nerves were affected in seven patients each (29.2%) and five patients (20.8%) had 7 th cranial nerve palsy. Approximately 38% of patients with cranial nerve palsies had systemic disorders (16.7% systemic hypertension; 12.5% DM). The relationship between cranial nerve palsy and systemic disorder was statistically significant (P < 0.01). Conclusion: This is the first study in the literature on ocular cranial nerve palsies in Southern Nigeria. Third and sixth cranial nerve palsies were the most common cases to present to the University of Port Harcourt Teaching Hospital Eye Clinic. There was a statistically significant association to systemic disorders such as hypertension and DM and majority of cases with 6 th cranial nerve palsy. Access this article online Website: DOI: / Quick Response Code: Key words: Cranial Nerve Palsies, Eye Clinic, Port Harcourt INTRODUCTION Cranial nerve palsy is a form of palsy involving one or more of the cranial nerves. It may cause a complete or partial weakness or paralysis of the areas innervated by the affected nerve. Cranial nerve palsies can be congenital or the result of traumatic or vascular disorders (hypertension, diabetes mellitus (DM), stroke, aneurysms). They can also be due to infections, migraine headaches, tumors or elevated intracranial pressure. The age of the patient as well as clinical findings suggests the type of diagnostic tests required to determine the probable etiology. The 3 rd, 4 th and 6 th cranial nerve palsies can limit eye movements and produce diplopia. The orientation of the diplopia is usually based on the affected cranial nerve. In addition to the limitation of eye movements, a 3 rd nerve palsy can also cause ptosis or mydriasis. Some cranial nerve palsies are easy to identify because they affect eye movements or facial expression with resultant difficulty in controlling eye movements or engaging in facial expressions such as smiling. Some cranial nerve palsies resolve spontaneously, especially if they are due to microvascular causes such as DM and hypertension. Department of Surgery (Ophthalmology Unit), College of Health Sciences, University of Port Harcourt, Port Harcourt, Nigeria Corresponding Author: Dr. Pedro Egbe Chinyere Nnenne, Department of Surgery (Ophthalmology Unit), College of Health Sciences, University of Port Harcourt, Port Harcourt, Nigeria. E mail: cpegbe@weltekng.com 170 Middle East African Journal of Ophthalmology, Volume 21, Number 2, April - June 2014

2 Of all ocular cranial nerve palsies, several authors have reported that 6 th cranial nerve palsy was the most common, followed by the 3 rd and then 4 th cranial nerves. 1 3 From these studies, the common causes of ocular cranial nerve palsies include head trauma, space occupying lesions, and vascular lesions (DM, hypertension and atherosclerosis). 2 In a cohort of 915 stroke patients, Rowe et al., reported ocular motor cranial nerve palsies in 10% of the patients. 4 Most (58%) of the palsies involved the 6 th nerve, followed by the 3 rd (26%) and then the 4 th cranial nerves (16%). 4 They 4 reported unilateral third nerve palsy in 23 patients (26%), unilateral fourth nerve palsy in 14 patients (16%) and unilateral sixth nerve palsy in 52 patients (58%). They 4 found that the most common location of a stroke lesion causing cranial nerve palsy was the brainstem or cerebellum. They also reported that the presence of manifest strabismus was significantly higher in third and fourth nerve palsies than sixth nerve palsy. This study provides clinical information and the frequency of the most common types of cranial nerve palsies evaluated at the University of Port Harcourt Teaching Hospital Eye Clinic and their association to systemic disorders. MATERIALS AND METHODS A retrospective chart review was performed of all patients with cranial nerve palsies who presented to the University of Port Harcourt Teaching Hospital Eye Clinic from January 2009 to December Data were collected and analyzed on age, sex, history of systemic disease such as diabetes mellitus, hypertension and cerebrovascular disease. The details of the systemic diseases were recorded from the patient charts. Ocular examination data were collected on the presenting symptoms and signs, visual acuity, range of extraocular motility and pupillary light reaction. Visual acuity was assessed with a Snellen chart. Our diagnosis of cranial nerve palsy was mainly clinical and was based on the presenting symptoms and signs, which included severe headaches and fever, ptosis, diplopia, lagophthalmos, deviation of the mouth to one side, esotropia, exotropia, hypertropia or complete ophthalmoplegia. Computed tomography of the brain was performed in 9 patients; 8 were within normal limits and one showed an intracranial mass. Exclusion criteria included case files with incomplete records (five) and the only case resulting from orbital trauma. Data were analyzed using Epi info Version 6.04D (Centers for Disease Control and Prevention, Atlanta, GA, USA). P values less than 0.05 were considered statistically significant. This study adhered to the Tenets of the Declaration of Helsinki. RESULTS A total of 24 patients presented with cranial nerve palsies. There were 11 males and the male to female ratio was 1:1.2. The mean age of the patients was ± years (range, 4 years to 75 years). The age and gender distribution of the study subjects is as presented in Table 1. Most of the patients with cranial nerve palsies (N = 14/24; 58.3%) were between 20 years and 39 years old [Table 1]. The most common presenting symptoms were headache and diplopia, affecting 7 (21.2%) patients each; this was followed by fever in 5 patients (15.2%) [Table 2]. Visual acuity was normal (VA = 6/6) in 41 eyes (85.4%), impaired (VA <6/18) in 6.3% (N = 3) eyes and 4 eyes (8.3%) were blind (VA = <3/60). Table 3 presents the ocular findings. Two patients each (13.3%) had 15 exotropia and 15 esotropia, respectively, while two patients each (13.3%) had severe ptosis and complete ophthalmoplegia. Three patients (20.0%) had lagophthalmos and 8 of the 24 patients (33.3%) had sluggishly reactive pupils. Table 4 presents the type of cranial palsy. The 3 rd and 6 th cranial nerves were affected in seven patients each (29.2%; N = 7/24) Table 1: Age and gender distribution of patients with cranial nerve palsies Age group (Years) Sex Total Male Female < (0.0) 2 (8.3) 2 (8.3) (25.0) 5 (20.8) 11 (45.8) (8.3) 1 (4.2) 3 (12.5) (0.0) 1 (4.2) 1 (4.2) (8.3) 2 (8.3) 4 (16.7) (4.2) 1 (4.2) 2 (8.3) (0.0) 1 (4.2) 1 (4.2) Total 11 (45.8) 13 (54.2) 24 (100.0) Chi square=4.29, P=0.64* not statistically significant Table 2: Presenting symptoms of patients with cranial nerve palsies Symptoms Frequency (%) Headache 7 (21.2) Diplopia (horizontal and vertical) 7 (21.2) Fever 5 (15.2) Negative scotoma 2 (6.1) Eye ache 1 (3.0) Blurred vision 2 (6.0) Cannot close right upper eyelid 1 (3.0) Drooping of right upper eyelid 2 (6.1) Drooping of the left upper eyelid 2 (6.1) Otalgia 2 (6.1) Deviation of the mouth to the left 1 (3.0) Neck stiffness 1 (3.0) Total 33 (100.0) Middle East African Journal of Ophthalmology, Volume 21, Number 2, April - June

3 while five patients (20.8%) had 7 th cranial nerve palsy [Table 4]. Only four patients (16.6%) had multiple cranial nerve palsies [Table 4]. The relationship between cranial nerve palsy and pupillary reaction is presented in Table 5. Most cranial nerve palsies (70.8%; N = 17/24) were associated with normal pupillary reaction [Table 5]. Only 29.2% of cranial nerve palsies were associated with sluggishly reactive pupils. Those with 3 rd and multiple cranial nerve palsies had sluggishly reactive pupils. The relationship between cranial nerve palsies and pupillary reaction was statistically significant (P = 0.02) [Table 5]. Table 6 presents the relationship between cranial nerve palsy and age. Most patients (48.3%; N = 11/24) with cranial nerve palsies were aged between 20 and 29 years old [Table 6]. This is followed by those in the year age range, making up 16.7% (N = 4) of all cases of cranial nerve palsies [Table 6]. This relationship was statistically significant (P < 0.01) [Table 6]. Table 3: Physical findings (ocular) of patients with cranial nerve palsies Table 4: Type of cranial nerve palsy in patients presenting to the University of Port Harcourt Teaching Hospital Eye Clinic Type of Palsy Frequency (%) 3 rd cranial nerve (LE) 4 (16.7) 3 rd cranial nerve (RE) 3 (12.5) 4 th cranial nerve 1 (4.2) 6 th cranial nerve (LE) 2 (8.3) 6 th cranial nerve (RE) 5 (20.8) 7 th cranial nerve palsy (RE) 5 (20.8) Multiple cranial nerves (LE) 2 (8.3) Multiple cranial nerves (RE) 2 (8.3) Total 24 (100.0) Table 5: Relationship between cranial nerve palsy and pupillary reaction Cranial nerve palsy Pupillary reaction Total (%) Sluggish (%) Active (%) 3 rd cranial nerve 3 (12.5) 4 (16.7) 7 (29.2) 4 th cranial nerve 0 (0.0) 1 (4.2) 1 (4.2) 6 th cranial nerve 0 (0.0) 7 (29.1) 7 (29.2) 7 th cranial nerve 0 (0.0) 5 (20.8) 5 (20.8) Multiple cranial nerves 4 (16.7) 0 (0.0) 4 (16.6) Total 7 (29.2) 17 (70.8) 24 (100.0) Chi square=18.54, P=0.02* statistically significant Frequency (%) 15 Exotropia 2 (13.3) 15 Esotropia 2 (13.3) 15 Hypertropia 1 (6.7) 30 Esotropia 1 (6.7) 45 Exotropia 2 (13.3) Complete ophthalmolplegia 2 (13.3) Lagophthalmos 3 (20.0) Severe ptosis 2 (13.3) Total 15 (100) Table 7 presents the relationship between cranial nerve palsy and systemic disorders. About 38% of those with cranial nerve palsies had systemic disorders. Of these, two (12.5%) were diabetic, four had systemic hypertension (16.7%) and one each had asthma, cerebral malarial and hearing loss [Table 7]. The relationship between cranial nerve palsy and systemic disorder was statistically significant (P < 0.01) [Table 7]. There was however no statistically significant difference between cranial nerve palsy and those with fever (not shown on table). DISCUSSION Over a three year period, only 24 cases of cranial nerve palsies presented, compared to other studies where larger numbers were seen. This is not surprising as stroke patients are rarely referred to our clinic from the medical outpatient department of the Hospital. The few patients who presented were walk ins without referral. Similarly, some cases, especially facial nerves palsies are managed by the ENT department explaining the very small number reported here. Our results show that most of the patients with cranial nerve palsies were between 20 and 39 years of age with a mean of ± years (range, 4 75 years). This differs from a study by Rowe et al., 4 where the mean age was ± years (range, 1 94 years). This difference is not surprising since Rowe et al., 4 study involved only stroke patients which may have accounted for the older age group as the risk factors to developing a stroke are greater in older individuals. The most common presenting symptoms were headaches, fever, diplopia and ptosis. Diplopia and ptosis are in keeping with the functions of some of the affected cranial nerves. The only patient with fever and neck stiffness had meningitis. Other fevers were ruled out as malaria as it is endemic in our region and commonly presents as fever. In our study, most patients (87.5%) had horizontal diplopia. This was expected as the 3 rd and 6 th cranial nerves were the most affected. In a study of stroke patients, Rowe et al., 4 reported that the 3 rd and 6 th cranial nerves were most affected, similar to our study. Of the seven patients with 6 th cranial nerve palsy, four were hypertensive, two were diabetic and one patient had cerebral malaria. This concurs with other studies where abducens palsy is considered the most commonly encountered extraocular muscle palsy with an incidence of 11.3 per 100,000 people. 5 Berlit et al., 6 in their study of 165 patients suffering from abducens nerve palsy found that a vascular origin (29.7%) was the most common, followed by inflammatory diseases (19.4%) and tumors (10.9%), while traumatic abducens paresis (3.1%) was rare. This confirms an earlier report by Moster 7 who identified vascular pathologies such as diabetes mellitus, hypertension and atherosclerosis. Moster found the vascular group was older compared to the younger group with multiple sclerosis and tumors as the more common causes Middle East African Journal of Ophthalmology, Volume 21, Number 2, April - June 2014

4 Table 6: Relationship between cranial nerve palsy and age Age groups Cranial nerve palsy Total (%) 3 rd Cranial N 4 th Cranial N 6 th Cranial N 7 th Cranial N Multiple CN < (4.2) 1 (4.2) 2 (8.3) (20.8) 2 (8.3) 3 (12.5) 1 (4.2) 11 (48.3) (4.2) 1 (4.2) 1 (4.2) 3 (12.5) (4.2) 1 (4.2) (4.2) 2 (8.3) 1 (4.2) 4 (16.7) (4.2) 1 (4.2) 2 (8.3) (4.2) 1 (4.2) Total 7 (29.2) 1 (4.2) 7 (29.2) 5 (20.8) 4 (16.7) 24 (100) Chi square=52.42, P<0.01* statistically significant Table 7: Relationship between cranial nerve palsy and systemic disorder Cranial nerve palsy Systemic disorder DM HTN Asthma Cerebral malaria Hearing loss Total 3 rd cranial nerve 4 th cranial nerve 6 th cranial nerve 2 (8.3) 4 (16.7) 1 (4.2) 7 (29.1) 7 th cranial nerve 1 (4.2) 1 (4.2) Multiple cranial 1 (4.2) 1 (4.2) nerves RE Total 2 (8.3) 4 (16.7) 1 (4.2) 1 (4.2) 1 (4.2) 9 (37.5) Chi square=52.42, P<0.01* statistically significant The mechanism of traumatic abducens nerve palsy may be direct mechanical injury or an indirect injury. The indirect injury results from nerve ischemic change due to vessel compression or vasospasm. 8,9 The three cranial nerves (3 rd, 4 th and 6 th ) are fed by a comprehensive network of arterial blood vessels, and thus are susceptible to vascular compromise particularly localized lesions and disturbances at the level of the brainstem cranial nerve nuclei as well as in the cavernous sinus just before innervating the extraocular muscles. 10 Paralysis of the 6 th cranial nerve has no localizing value because it may be affected by, almost any type of cerebral lesion. Many theories have been proposed for this observation. 11 Collier thought that this happens because of the shifting backwards of the brainstem since the direction of the nerve is mostly fronto caudal. Affection of the 6 th nerve is followed by the 3 rd, 7 th and 8 th cranial nerves. The more fragile 4 th nerve with its longer intracranial course (75 mm) is less affected because it is thought to be protected by, the free margin of the tentorium cerebelli. Alternately, the 6 th nerve, has the longest extradural course (even though its entire length is 1/3 that of the 4 th nerve), thereby making it vulnerable to intracranial insults as seen in meningitis and subarachnoid hemorrhage. 12 Cushing 13 postulated that when the anterior inferior cerebellar artery ran ventral to the 6 th nerve it may press on and groove the nerve and the underlying pons due to increased intracranial pressure and thus cause lateral rectus palsy. Another author suggested that the bend over the sharp apex of the petrous temporal bone exposes the 6 th nerve to insult when there is an increase in intracranial pressure with resultant coning of the brain. If the 6 th nerve is fixed to the pons and more or less held in the cavernous sinus, it will therefore be pressed up against the sharp border of the petrous temporal bone causing an interruption in conduction and palsy of the lateral rectus. A similar condition may follow compression of the skull in difficult labor with or without forceps and may explain 6 th nerve palsy at birth. A review of the medical literature 11,12 has shown that abducens nerve vulnerability results from factors other than its intracranial length. Of the 24 patients we reviewed, only 9 underwent neuro imaging. Eight results were normal and one showed an intracranial space occupying lesion. The observation that the neuro imaging results were normal should not give a false sense of hope. This was shown in a case reported by Hoenig 14 of a 62 year old male with facial nerve palsy who was managed over an 18 month period with initial normal magnetic resonance imaging results. Hoenig 14 therefore cautioned that normal neuro imaging results might be falsely misleading in identifying the cause of cranial nerve palsy. In the current study, approximately one third (33.3%) of the patients had sluggishly reactive pupils; and the relationship between cranial nerve palsy and pupillary reaction was statistically significant (P = 0.02). Complete 3 rd nerve palsy would almost definitely affect pupillary reaction, hence this result is not unexpected. All cases of 7 th cranial nerve palsy were idiopathic except one patient who had associated hearing loss. Recent research has shown that Bell s palsy occurs when the herpes simplex virus gets reactivated in the temporal bone. 15 This may explain the associated otalgia in one of the patients. Middle East African Journal of Ophthalmology, Volume 21, Number 2, April - June

5 Bell s palsy is the most common facial nerve palsy encountered, accounting for approximately 75% of cases. 16 The limitations of this study included the very small sample size, and most patients were lost to follow up. Hence it is difficult to assess the final outcome of management. A future study involving other departments that manage patients with cranial nerve palsies is required. CONCLUSION The most common cranial nerve palsies in patients present at the University of Port Harcourt Teaching Hospital Eye Clinic were the 3 rd and 6 th cranial nerves, followed by the 7 th nerve. Most cases of 6 th cranial nerve palsy were related to systemic disorders such as hypertension, DM and cerebral malaria. This association was statistically significant. A further study involving other relevant departments would provide a more comprehensive summary of the frequency of the occurrence of cranial nerve palsies. REFERENCES 1. Rush JA, Younge BR. Paralysis of cranial nerves 3, 4 and 6. Cause and prognosis in 1000 cases. Arch Ophthalmol 1981;99: Rucker CW. The causes of paralysis of the third, fourth and sixth cranial nerves. Am J Ophthalmol 1966;61: Richards BW, Jones FR Jr, Younge BR. Causes and prognosis in 4,278 cases of paralysis of the oculomotor, trochlear, and abducens cranial nerves. Am J Ophthalmol 1992;113: Rowe F; VIS group UK. Prevalence of ocular motor cranial nerve palsy and associations following stroke. Eye (Lond) 2011;25: Patel SV, Mutyala S, Leske DA, Hodge DO, Holmes JM. Incidence, associations, and evaluation of sixth nerve palsy using a population based method. Ophthalmology 2004;111: Berlit P, Reinhardt Eckstein J, Krause KH. Isolated abducens paralysis a retrospective study of 165 patients. Fortschr Neurol Psychiatr 1989;57: Moster ML, Savino PJ, Sergott RC, Bosley TM, Schatz NJ. Isolated sixth nerve palsies in younger adults. Arch Ophthalmol 1984;102: Kim MS, Cho MS, Kim SH. Delayed bilateral abducens nerve palsy after head trauma. J Korean Neurosurg Soc 2008;44: Ayberk G, Ozveren MF, YildirimT, Ercan K, Cay EK, Koçak A. Review of a series with abducens nerve palsy. Turk Neurosurg 2008;18: Ciuffreda KJ, Kapoor N, Rutner D, Suchoff IB, Han ME, Craig S. Occurrence of oculomotor dysfunctions in acquired brain injury: A retrospective analysis. Optometry 2007;78: Last RJ. Eugene Wolff s Anatomy of the Eye and Orbit. 6 th ed. Nerves, Chapter 6. London: HK Lewis and Co. Ltd; p Milanes Rodríguez G, Ibañez Valdés L, Foyaca Sibat H, Perez Fernandez M. The abducens nerve in neurology. Internet J Neurol 2008;10: Cushing H. Strangulation of the nervi abducens by lateral branches of the basilar artery in cases of brain tumor: With an explanation of obscure palsies on the basis of arterial constriction. Brain: A journal of Neurology 1910; 33: Hoenig PA. Multiple cranial nerve palsies. N Engl J Med 1990; 322: Bell s palsy diagnosis and treatment. Available from: com/5/bellpalsy. html. [Last accessed on 2013 Oct 13]. 16. Peitersen E. Bell s palsy: The spontaneous course of 2,500 peripheral facial nerve palsies of different etiologies. Acta Otolaryngol Suppl 2002;(549):4 30. Cite this article as: Pedro-Egbe CN, Fiebai B, Awoyesuku EA. A 3-year review of cranial nerve palsies from the University of Port Harcourt Teaching Hospital Eye Clinic, Nigeria. Middle East Afr J Ophthalmol 2014;21: Source of Support: Nil, Conflict of Interest: None declared. 174 Middle East African Journal of Ophthalmology, Volume 21, Number 2, April - June 2014