Idiopathic Recurrent Polyneuritis Cranialis: A Rare Entity

Recurrent polyneuritis cranialis is a rare disorder that can affect multiple cranial nerves. We describe a young man who presented with recurrent cranial nerve (CN) palsies. His first episode at 17 years of age involved the right VI cranial nerve, the second episode at age 21 involved the left V and VII cranial nerves while the last episode six months later affected the left IV cranial nerve. Based on the clinical findings and laboratory test results to exclude other possibilities, a diagnosis of idiopathic recurrent polyneuritis cranialis was made. This is a very rare disorder in childhood and adolescence. This is the youngest patient ever reported with recurrent polyneuritis cranialis of unknown etiology.

It is thought that the pathological mechanism is related to microinfarction of cranial nerves due to occlusion of the vasa nervorum [3]. The syndrome usually, but not always, consists of a long prodromal headache and facial pain of subacute onset preceding the abrupt onset of multiple cranial nerve palsies [13]. An IRB approval was waived because of the nature of this

Case Presentation
First event A 17-year-old male presented for evaluation with an episode of horizontal diplopia to his doctor in his home country. He was "unable to move his right eye outwards." He did not complain of ear pain, headaches, nausea, neck pain, or vomiting. His symptoms resolved spontaneously in two to four weeks. Despite a thorough workup, no etiology was found and a diagnosis of right cranial nerve (CN) VI nerve palsy was made.  He was diagnosed with Bell's palsy and treated with prednisone for five days with complete resolution of symptoms.

Third event
He returned to the emergency room (ER) six months later with a sudden episode of double vision. He had some upper respiratory symptoms four days prior to the onset and was treated with amoxicillin-clavulanic acid. He had no associated pain, history of recent head or neck trauma, numbness or tingling of the face, facial asymmetry, or trouble swallowing or with speech. He denied visual aura, decreased vision, or other visual complaints. There was no diurnal fluctuation. The general exam was normal. His speech was fluent without any paraphasic errors and his comprehension was intact. The cranial nerves were intact except for left IV cranial nerve palsy.
Given his recent history of sinusitis, cavernous sinus thrombosis was considered but magnetic resonance imaging/ magnetic resonance venography (MRI/MRV) did not show evidence of thrombosis, demyelinating condition, tumor or bleeding. It only showed a Rathke cyst in the pituitary gland that was not compressive of any anatomic areas and was thought to be incidental. He was diagnosed with left IV cranial nerve palsy.

Discussion
In 1970, Steele and Vasuvat published an article claiming to have seen 14 adults with recurrent multiple cranial nerve palsies; however, out of the 14 patients, 12 were non-recurrent and none presented in the same pattern or the sequence of our patient. There were descriptions of only four cases in the report with details. The rest of the patients presented with different pathologies that ultimately led to secondary cranial neuropathies [1]. One out of two patients who had a relapse was initially diagnosed with optic neuritis.
Yagnik and Dhaduk reported polyneuritis cranialis as a complication of Lyme's disease [14] and it has also been quoted as a manifestation subtype of GBS [15,16], but it was non-recurrent in both cases.
The preservation of tendon reflexes in idiopathic cranial neuropathy is the major clinical feature to distinguish PNC from GBS [2,5,15]. Our patient did not have any abnormality in his deep tendon reflex in upper and lower limbs.
Myasthenia gravis (MG) must be considered as well when a patient presents with sudden symptoms of diplopia, hence a measurement of anti-acetylcholine receptor antibody (blocking and binding) was performed and an extensive workup for myasthenia was negative; however MG is characterized by a steady progression to complete ophthalmoplegia or by relapses and remissions, and typically affects both eyes (ptosis) rather than one [17]. In our patient, only the left IV cranial nerve was involved.
Botulism was also considered in the differential diagnoses; however, affected patients subsequently developed generalized weakness [2]. Tolosa-Hunt syndrome is caused by an idiopathic granulomatous inflammation of the cavernous sinus and shares many features with PNC, like cranial nerve palsies, III, IV and first division of V [2,4,8]. It was considered because of the ophthalmoplegia [2,4,8], but because he had no pain and his MRI was negative, this syndrome was ruled out. Sarcoidosis which is a chronic systemic inflammatory disorder that is characterized by the formation of noncaseating granuloma may present with cranial nerve VI and VII palsies commonly [4]. In our patient a negative Angiotensin-converting enzyme (ACE) test, a normal chest X-ray and non-clinical findings suggestive of this disease allowed us to rule it out.
Typically, polyneuritis cranialis is preceded by a long prodromal headache and/or facial pain of subacute onset. Lee suggested that a headache should be considered as an additional cardinal feature of PNC along with multiple cranial neuropathies [1]. Ophthalmoplegic migraine was considered due to the fact that cranial nerves V and VII are usually affected in ophthalmoplegic migraine and a transitory ocular motor palsy that sometimes lasts as long as four weeks have been also reported [2], even though a headache was not the first symptom and was not prominent in any of the episodes.
Dosunmu indicated that most isolated fourth nerve palsies are congenital, even those presenting in adulthood [4,18,19]. The most common causes of acquired lesions are trauma and microvascular disease [4,18,19].
Polyneuritis cranialis has been described in conjunction with various conditions ( Table 5).

Diagnostic tests
Guillain-Barre   [20]; however, in our patient VZV polymerase chain reaction in the cerebrospinal fluid was negative, ruling out a VZV infection. The VZV PCR is highly sensitive and specific [2,3,20].
The management of multiple cranial neuropathy palsies relies on accurate diagnosis with specific therapy aimed at the underlying cause [2]. A lack of clear etiology represents a management challenge and specific recommendations cannot be made. Empiric therapy with corticosteroids seems a logical management option [2,15]. The etiology cause of our patient was then finally categorized as idiopathic.

Conclusions
This is the youngest patient ever reported with recurrent polyneuritis cranialis of idiopathic etiology with a very odd sequence of cranial nerve palsy affecting the right VI, left V, left VII and left IV cranial nerves without prominent associated symptoms. GBS, sarcoidosis, Lyme disease, VZV, myasthenia gravis, ophthalmoplegic migraine, masses' infiltrative processes should remain in the differential. The outcome was excellent despite the lack of specific therapies suggesting a benign course. Clinicians must be aware of this rare entity to avoid unnecessary testing and to provide a more effective diagnosis and counseling to patients. As is usual in case reports, more cases are needed to characterize this unique clinical diagnosis.

Disclosures
Human subjects: Consent was obtained by all participants in this study.

Conflicts of interest:
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