"Salt and Pepper" Pontine Infarct

A paramedian pontine stroke may herald the unique symptom of "salt and pepper" eye pain, in which patients describe the sensation of pepper rubbed into the eye. While localization of the lesion is a common thread among published cases, the mechanism for the sensation of eye pain is still a matter of conjecture. It is important for clinicians to be aware of this unique symptom because strokes rarely present with eye pain and failure to establish this diagnosis might lead to a poor clinical outcome.

Clinical Observation "Salt and Pepper" Pontine Infarct Lance J. Lyons, BA, Susan W. Law, DO, John L. Kubie, PhD Abstract: A paramedian pontine stroke may herald the unique symptom of "salt and pepper" eye pain, in which patients describe the sensation of pepper rubbed into the eye. While localization of the lesion is a common thread among published cases, the mechanism for the sensation of eye pain is still a matter of conjecture. It is important for clinicians to be aware of this unique symptom because strokes rarely present with eye pain and failure to establish this diagnosis might lead to a poor clinical outcome. Journal of Neuro-Ophthalmology 2017;37:276-280 doi: 10.1097/WNO.0000000000000437 © 2016 by North American Neuro-Ophthalmology Society "S alt and pepper" strokes are rare clinical presentations of acute ischemic events involving the brainstem. Classically, patients complain of burning eye pain, as if pepper were rubbed onto the ocular surface and surrounding structures. The entity was first described by Caplain and Gorelick (1), who reported 3 such cases with infarcts clinically localized to the brainstem, namely, the paramedian basis points and tegmentum. Because eye pain can be the sole presenting symptom, it is important for clinicians to be aware that such a complaint may require a stroke evaluation. CASE REPORT A 48-year-old, hypertensive, diabetic woman presented to the emergency department after experiencing right ophthalmodynia and subsequent left hemiparesis. She was in her usual state of health until the night before admission, SUNY Downstate College of Medicine (LJL), Brooklyn, New York; Department of Neurology and Stroke Center (SWL), SUNY Downstate Medical Center, Brooklyn, New York; Department of Cell Biology (JLK), SUNY Downstate Medical Center, Brooklyn, New York. The authors report no conflicts of interest. Address correspondence to Lance J. Lyons, BA, SUNY Downstate Health Science Center, 222 Lenox Road, Apt 2E Brooklyn, NY 11226; E-mail: [e-mail] 276 when she reported 10/10 stinging right eye pain "as if someone rubbed pepper in my eye" but denied headache, diplopia, tearing, or dryness of the eye. The following morning, the patient noticed new onset left-sided weakness. Her medications consisted of insulin and amlodipine/ benazepril. On examination, visual acuity, slit-lamp examination, and funduscopy were normal. Visual fields by confrontation were full. Neurological testing revealed mild left-sided weakness and pronator drift with ipsilateral decreased cold sensation. Trigeminal nerve sensation was intact. Brain MRI revealed paramedian pontine infarct (Fig. 1). The patient was treated with aspirin, and 3 months later, she had residual left upper extremity weakness and increased tone, left sensory deficits to light touch in the arm, leg, and face, occasional occipital headaches, and moments of burning right eye pain. DISCUSSION The association of "salt and pepper" stinging eye pain and paramedian pontine infarction has been well documented with patients referencing this specific complaint more or less verbatim (Table 1). In some cases, ophthalmodynia was the sole symptom heralding brainstem ischemia, while others presented with associated neurological complaints such as vertigo or a metallic taste in the mouth. In all but one, further neurological deficits followed the onset of eye pain, ranging in severity from hemiparesis (both ipsilateral and contralateral to the affected eye) to cardiac and respiratory arrest with brainstem failure (2). Because of the brainstem anatomy of the vasculature, in smaller occlusions of the basilar artery, the central pons, consisting mainly of the paramedian but possibly a small portion of the ventral pontine tegmentum, is affected. Second-order neurons in the pars caudalis, one of 3 subnuclei of the spinal trigeminal nucleus, convey nociceptive information from the head along axons, which cross diffusely within the tegmentum. Damage to this pathway represents one possible origin of the salt and pepper Lyons et al: J Neuro-Ophthalmol 2017; 37: 276-280 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 1. Diffusion-weighted imaging and corresponding apparent diffusion coefficient maps demonstrate an ischemic infarction of the pons (arrows) with basilar (A) and tegmental (B) involvement. clinical syndrome but would likely cause bilateral symptoms. Isolated anteromedial pontine infarcts commonly cause motor deficits and can produce neuro-ophthalmic abnormalities (such as diplopia, conjugate gaze palsy, and internuclear ophthalmoplegia) when mild tegmental involvement is present (7). However, the larger nature of the "salt and pepper" strokes has led Chen et al (6) to suggest the requirement of both basis pontis and tegmentum involvement in producing this symptom, possibly from damage to both nociceptive (trigeminothalamic tract) and more superior pain-modulatory (locus coeruleus, raphe nuclei, periaqueductal gray) centers. Alternatively, since the advent of the pain "gate theory," the sensory component of pain, rather than explained as purely transmitted via smalldiameter nociceptors, is considered to be a balance of nociceptive (small diameter) and mechanosensory (large diameter) fiber activities (8). Because disrupting this balance can enhance or diminish pain perception (5), it is possible that damaging the trigeminal mechanoreceptors traveling along the medial aspect of the medial lemniscus Lyons et al: J Neuro-Ophthalmol 2017; 37: 276-280 in the midline pontine tegmentum may induce the pain of this syndrome. The location of these fibers, near, but not in the midline, may explain how such damage, if unilateral, could affect only the contralateral eye. Interestingly, the primary afferent fibers descending in the lateral spinal trigeminal tract appear spared in cases of "salt and pepper" eye pain, while they are often damaged in cases of trigeminal neuralgic, facial, and, sometimes, ocular pain of a separate nature. The infarct in this case is consistent with previous MRI studies of "salt and pepper" strokes and adds to the growing literature on this singular diagnosis. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: L. J. Lyons, S. Law; b. Acquisition of data: L. J. Lyons, S. Law; c. Analysis and interpretation of data: L. J. Lyons, S. Law, J. Kubie. Category 2: a. Drafting the manuscript: L. J. Lyons, S. Law, J. Kubie; b. Revising it for intellectual content: L. J. Lyons, S. Law, J. Kubie. Category 3: a. Final approval of the completed manuscript: L. J. Lyons, S. Law, J. Kubie. 277 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Study Age (yr)/ Gender Pain Localization Associated Symptoms 54/M Bilateral eye and face, R . L 40/F Right eye and ear 58/M Eye and nose, L . R Ito et al (2) 11/F Left eye and face Doi et al (3) 42/M Right eye and nose Left facial and extremity numbness, ataxia 58/F 42/M Left eye and nose Left internal canthus and nose 47/M Right eye Right facial and extremity tingling Right face and limb numbness; right ataxic hemiparesis and mild right-sided hypesthesia the following day Headache, vertigo 55/M Bilateral eye, left face None Caplain and Gorelick (1) Conforto et al (4) Episodic dizziness, left hemiparesis, difficulty sustaining right conjugate gaze Dizziness, slurred speech, ataxia, transient left lip numbness, left hemiparesis, left Babinski sign, increased left DTRs the following morning Metallic taste, vertigo, and left limb paresthesia 1 month prior Elevated BP, arrhythmia Course Neuroimaging Pain subsided, hemiplegia persisted the following day None Pain subsided Normal CT Not reported Midbasilar artery occlusion Fourth ventricle hemorrhage with extension into third ventricle Right-sided medial tegmental pontine infarct Left pontine infarct Left dorsal pontine infarct Cardiopulmonary arrest, coma for 1 month, gradual recovery Left-sided paresthesia, leftsided ataxic hemiparesis, left hypesthesia Resolution of symptoms Not reported Lyons et al: J Neuro-Ophthalmol 2017; 37: 276-280 Recurrence 15 days later with right hemiparesis, left hypesthesia, bilateral Babinski sign, dizziness, diplopia, left INO, and drowsiness. Transient right hemiparesis and pain recurrence 2 days later; bilateral ocular pain, hyperemia, and tearing with right hemiparesis 1 week later Bilateral paramedian pontine (base and tegmentum) infarct and proximal basilar artery occlusion Left pontine (base and tegmentum) infarct and severe proximal basilar artery stenosis Clinical Observation 278 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. TABLE 1. Reports of "salt and pepper" brainstem strokes Lyons et al: J Neuro-Ophthalmol 2017; 37: 276-280 Study Age (yr)/ Gender Pain Localization Associated Symptoms Course 64/F Right eye Left hand paresthesia Recurrences of eye pain, right limb paresthesia and hemiparesis, and dysarthria over the following days 56/F Bilateral eye and nostril None Pain resolved but left hemiparesis, Babinski sign, and increased DTRs the following morning Simon et al (5) 58/F Bilateral eye Slow but consistent recovery of motor function Chen et al (6) 41/M Bilateral eye and eyebrow 25/F Bilateral eye, eyebrown, and nostril Metallic taste, dizziness, right hemiparesis, dysphagia, central VII nerve palsy, and bulbar muscle weakness Diplopia, ataxia, facial tightness 6 hours after pain onset; internal ophthalmoplegia, right central facial weakness, and decreased sensation on right face the following day Diplopia, ataxia, facial tightness, internal ophthalmoplegia, and decreased sensation on right face 2 days after pain onset Collapsed and lost consciousness 10 minutes later Current Report 48/F Bilateral eye and forehead Bilateral eye and forehead Right eye Dizziness and palpitations, with diplopia, left hemiparesis, and loss of consciousness 30 minutes later Left hemiparesis and slurred speech the following morning Neuroimaging Left paramedian pons (base and tegmentum) and right pons (base) infarcts with basilar artery occlusion Right pontine (base and tegmentum) infarct with basilar artery atherosclerosis but no significant stenosis Large left paramedian pontine infarction Eye pain resolved after 1 day, neurologic deficits resolved after 2 months Bilateral pontine tegmentum hemorrhage extending mildly to the basilar pons Pain resolved after 3 days; internal ophthalmoplegia and ataxia did not fully recover Lower pontine (base and tegmentum) hematoma Coma, respiratory failure, quadriplegia Large pontine hematoma on CT Left hemiplegia, stupor Large pontine hematoma on CT Gradual recovery of motor function Right paramedian pontine infarct BP, blood pressure; CT, computed tomography; DTRs, deep tendon reflexes; F, female; INO, internuclear ophthalmoplegia; L, left; M, male; R, right. Clinical Observation 52 or 62/ M (age unclear from report) 75/M 279 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. (Continued ) Clinical Observation REFERENCES 1. Caplain L, Gorelick P. "Salt and pepper on the face" pain in acute brainstem ischemia. Ann Neurol. 1983;13:344-345. 2. Ito M, Wachi A, Sumie H, Sato K, Ishi S. "Salt and pepper on the face" pain followed by cardiac and respiratory arrests. The stormy postoperative manifestations after the surgery of posterior fossa arteriovenous malformation. Clin Neurol Neurosurg. 1989;91:145-151. 3. Doi H, Nakamura M, Suenaga T, Hashimoto S. Transient eye and nose pain as an initial symptom of pontine infarction. Neurology. 2003;60:521-523. 4. Conforto AB, Martin Mda G, Ciríaco JG, Leite CC, Campos CR, Yamamoto FI, Puglia P Jr, Gattás G, Scaff M. "Salt and pepper" 280 5. 6. 7. 8. in the eye and face: a prelude to brainstem ischemia. Am J Ophthalmol. 2007;144:322-325. 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