Oculomotor Nerve Palsy due to arterial compression

Oculomotor Nerve Palsy due to arterial compression relieved by microvascular decompression

Nakagawa H, Yamada M, Maeda M, Fukuda A, Tamura MDept. of Neurosurgery, Nozaki Tokushukai Hospital, Osaka, Japan

IntroductionVascular compression of the root entry/exit zone or central segment(glial part) of the cranial nerves cancause facial spasm, trigeminal neuralgia, glossopharyngeal neuralgia, hypertension, vertigo, spasmodic torticollis and megadolichobasilar anomaly. These conditions are all hyperactive dysfunctions. Hyperactivity of the oculomotor nerve causing ocular muscle spasm is possibly caused by compression of the central nerve segment. However, impaired visual acuity and visual fields caused by vascular compression of the optic nerve are considered to be due to neuropathy. In this way, oculomotor palsy also occurs when the cisternal nerve segment without a central myelin is compressed by a vessel.

Oculomotor nerve palsy (ONP) usually occurs due to direct compression by an aneurysm, and diabetes mellitus, infections such as tuberculosis and syphilis, and autoimmune disorders, trauma and history of ophthalmoplegic migraine are also known as the other sources. This symptoms has been reported to disappear naturally within a year in two third of the patients except for the case with an aneurysm. However, 50% of the patients develops permanent incomplete ONP causing the decrease of performance status in daily life. We reported a case with bilateral ONP occurred at different times relieved by microvascular decompression in 1991. Then, we have been tried to cure idiopathic OPN suggesting vascular compression from the finding of MRI without apparent other sources by microvascular decompression.

Methods & Objects

We show the number of my cases of each vascular compression syndrome (Table 1). We performed 20 cases of 18 patients developing oculomotor palsy whom we got full informed consent (Table 2). Patients without diabetes mellitus, infections described above, autoimmune disorders and trauma were selected under the diagnosis of imaging studies. In initial stage, we applied subtemporal approach, then we performed by pterional approach. We evaluated the selection of surgical approach for ONP.

Background : Oculomotor nerve palsy ONP) usually occurs due to direct compression by an aneurysm, and diabetes mellitus, infections such as tuberculosis and syphilis, and autoimmune disorders, trauma and history of migraine are also known as the other sources. This symptoms has been reported to disappear naturally within a year in two third of the patients except for the case with an aneurysm. However, 50% of the patients develops permanent incomplete ONP causing the decrease of performance status in daily life. We reported a case with bilateral ONP occurred at different times relieved by microvasculardecompression in 1991. Then, we have been tried to cure idiopathic OPN suggesting vascular compression from the finding of MRI without apparent other sources by microvascular decompression.Methods & Objects: We performed 20 cases of 18 patients whom we got full informed consent. In initial stage, we applied subtemporal approach, then we performed by pterional approach. We evaluated the selection of surgical approach for ONP. Results: Two male patients demonstrated bilateral OPN occurred at different times. Average age was 59 years old. The ratio of male to female was 8:10. The right and left difference was 9:11. The time from onset of ONP to surgery ranged from 2 to 30 days, and the interval within one week was 6, and the 14 cases were longer than 10 days. Eighteen of 20 surgical cases showed complete recovery. The offending artery was posterior cerebral artery in 15 cases, basilar・superior cerebellar artery in 2 cases and 3 fetal type of posterior communicating artery. However, it was not easy to move big basilar artery from the oculomotor nerve when the offending artery is big basilar artery, which is clearly comfirmed by MRI. The interval from surgery to recovery of OPN ranged two weeks to three months.Conclusion: Microvascular decompression is useful treatment method to relieve ONP caused by vascular compression even for cases lasting for one month, although it is not easy to cure the cases caused by big basilar artery such as megadolichobasilar anomaly. Regarding the surgical approach : the pterional approach can cover all cases by opening the sylvian fissure to most extent.

Key words: oculomotor nerve palsy, vascular compression, microvascular decompression

Abstract

Table 1

Disease Symptoms Cranial nerve Cases

Facial spasm Spasm of unilateral face N VII 367

Trigeminal neuralgia Spasm of unilateral face N V1,2,3 152

Glossopharyngeal neuralgia Pharyngeal stabbing pain N IX 5

Vertigo attack Vertigo accompanying tinnitus N VIII 7

Spasmodic torticollis Spasm of unilateral neck N XI 4

Oculomotor palsy Ptosis N III 20

Visual field defect Lower defect of visual field defect N II 2

Neuro・vascular compression syndrome Case Age, Sex Site Duration ofsymptom

Offending vessels

Case No.

Age Sex Site Duration of symptom

Offending vessels Results

*1 59 M L 2 days PCA (P2) Complete Recovery

*2 74 F R 3 days BA, SCA Complete Recovery

3 61 F R 10 days PCA (P2) Complete Recovery

*4 51 M R 14 days PCA (P2) Complete Recovery

5 48 M L 7 days PCA (P2) Complete Recovery

6 68 F R 7 days PCA (P2) Incomplete recovery

7 52 F L 16 days PCA (P2) Complete Recovery

8 49 M L 14 days BA, SCA Complete Recovery


*10 69 F L 30 days Pcom Complete Recovery




14 62 F R 12 days Pcom Complete Recovery



17 56 F R 14 days BA, SCA Complete recovery

18 62 F L 13 days PCA (P2) Complete Recovery

19 49 M L 28 days PCA (P2) Incomplete Recovery

20 64 M R 26 days PCA (P2) Complete Recovery

Table 2

Case 1

Before the first operation

Right N IIIBefore the second operation

Left N III palsy

Postoperative

First Surgery

Second Surgery

N III

Pcom A

ICA

PCA

ICA:internal carotid arteryPcom:posterior communicating arteryPCA:posterior cerebral arteryNH:nerve hookN II:oculomotor nerve

tent

Ret

Ret

tent N III

SCA

PCA

Compressed part

BS

First operation through the leftfrontotemporal approach

Second operation through the right subtemporal approach

Ret:brain retractortent: tentoriumSCA: superior cerebellar arteryBS:brain stem

Junctional dilatation

Duplicate Pcom A

Brain stem showing depression by compression of BA

Case 2

N III

BA

N III N III

BA

BA: basilar arteryN III:oculomortor nerve

Right oculomotor palsy

Compressed partIC

N II

N III

ACA MCAPCA

Operative view through the right frontotemporal approach

DSA:red arrow showing the compressed part of PCACase 4

Lt. oculomotor palsyPreoperative view

7 days after surgery

Offending artery

Offending artery

Preoperative DSACase 10

P-Com Int.Carotid Art.N III Flattened and decolored NIII by compression of P-Com.

Int.Carotid Art.

P-Com

Sponge placed between PCA and N III

P-Com art. pulled up with silk thread

Decolorizationof the compressed portion of N III

Nerve hook

Operative view through left frontotemporal approach

ResultsTwo male patients demonstrated bilateral OPN occurred at different times. The average age of the participants was 59 years. The ratio of male to female was 8:10 and the right and left difference was 9:11. The time from onset of ONP to surgery ranged from 2 - 30 days. Six cases underwent surgery within one week. In 14 cases, the interval was longer than ten days. Eighteen cases showed complete recovery. The offending artery was the posterior cerebral artery in 15 cases, the basilar-superior cerebellar artery in two cases, and the fetal type of posterior communicating artery in three cases. However, it was not easy to move big basilar artery from the oculomotor nerve when the offending artery is big basilar artery, which is clearly comfirmed by MRI. The interval from surgery to recovery ranged two weeks to three months.

ConclusionMicrovascular decompression is a useful treatment method for ONP caused by vascular compression even for cases lasting for one month. However, it was challenging to cure the cases caused by the big basilar artery such as megadolichobasilar anomaly. The pterional approach by opening the sylvian fissure to the most extent was successful in all cases.

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Oculomotor Nerve Palsy due to arterial compression