Journal of the neurological Sciences, 18 (1973) 317-322 © Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands 317 Lateral Inferior Pontine Syndrome Clinico-pathologic Study and Review of Literature S. A L E K S I C AND G . B U D Z I L O V I C H Departments of Neurology and Pathology (Neuropathology), New York University School of Medicine, 550 First Avenue, New York, N. Y. 10016 (U.S.A.) (Received 31 August, 1972) INTRODUCTION S p o n t a n e o u s , focal, p o n t i n e h e m o r r h a g e w h i c h gives rise to a well d e f i n e d clinical synd r o m e is rare. T h e p u r p o s e o f this r e p o r t is t o d e s c r i b e t h e c l i n i c a l a n d p a t h o l o g i c a l d a t a o f a p a t i e n t w h o p r e s e n t e d w i t h a left facial p a r a l y s i s a n d i p s i l a t e r a l h e a r i n g loss o f s u d d e n onset. T h e u n u s u a l t o p o g r a p h y o f t h e h e m o r r h a g e f o u n d at n e c r o p s y will s e r v e as t h e b a s i s for t h e d i s c u s s i o n c o n c e r n i n g t h e r e l a t i o n s h i p b e t w e e n t h e v a s c u l a r l e s i o n s at t h e i n f e r i o r p o n t i n e level a n d t h e p e r t i n e n t n o m e n c l a t u r e c u r r e n t l y in g e n e r a l use. CASE REPORT G. R., a 60-year-old, right-handed male, was in good health apart from long-standing right-sided deafness due to an ear infection in childhood, until the morning of 3 April, 1971, when he developed numbness of the left side of the face and vague ipsilateral headaches. The following day, he noticed difficulty in walking and poor balance. Examination at that time showed only decreased pinprick and touch sensation over the left half of the face and marked hearing loss in the right ear of conductive type, present since childhood. One week later, he suddenly lost hearing in his left ear, becoming totally deaf. Twelve hr later left facial paralysis occurred. On the same day the patient was admitted to Bellevue Hospital for evaluation. His past medical history and family history were non-contributory. Review of symptoms revealed a 3-4 month history of lowback pain and a 30-pound weight loss. On admission, vital signs were normal. Positive findings on general physical examination included scarring and perforation of the right ear-drum, enlarged lymph nodes in both axillae, tenderness of the thoraeo-lumbar spine on percussion and an enlarged, hard prostate. The patient was alert, with normal speech and he was fully oriented. He followed promptly written commands and gestures; verbal contact was not possible on account of complete deafness. Cranial nerve examination showed the following abnormalities: slight limitation of conjugate gaze to the left ; nystagmus in all directions of gaze, more pronounced toward the left; all modalities of sensation were absent over the left half of the face, as was the left corneal response; there was a profound left facial paralysis of peripheral type and severe bilateral deafness. The remaining abnormalities on examination included a slight decrease in ability to perform rapid alternating movements with the left hand, an absent right plantar response, a broad-based gait and left finger-tonose and heel-to-shin ataxia. Romberg's test was equivocal. Correspondence to Dr. Aleksic, Bellevue Hospital, New York, 10016. (U.S.A.) 318 S. ALEKSIC, G. BUI)ZtLOVICtt Laboratory investigation gave findings consistent with a diagnosis of carcinoma of the prostatc with metastases in bone and bone marrow. It was felt that the patient's neurological symptoms were due to metastatic carcinoma in the left cerebello-pontine angle. No lumbar puncturc was performed and he was given steroids by mouth. Bilateral brachial angiograms were non-contributory. His neurological status remained unchanged until his sudden and unattended demise on the ninth hospital day. Pathological examination Necropsy was performed 24 hr after death (Dr. Ruacan). A poorly-differentiated adenocarcinoma of the prostate with metastases in bone and bone marrow was found, with foci of extramedullary hematopoiesis in the liver, kidneys, spleen and lymph nodes. The remaining organs were unremarkable; the right temporal bone and middle ear were not examined. Both ponto-cerebellar angles were free of t u m o r Neuropathological examination The brain was fixed in 10 ~ formalin solution and cut 2 weeks later. The only abnormalities on external examination were found on coronal sections of the cerebellum and brain stem, revealing an approximately ovoid, fairly well-delineated lesion (Fig. 1) which consisted of granular, diffusely hemorrhagic material. It had destroyed the following structures of the left side of the cerebellum and brain stem: most of the dentate nucleus, the intracerebellar portion of the middle cerebellar peduncle, one-third of the lateral pontine tegmentum, the dorsolateral fifth of the basis pontis, the inferior cerebellar peduncle and the central portion of the deep hemispheric white matter of the left cerebellar hemisphere. Rostro-caudally, the lesion extended from a level slightly above the point of entry of the roots of the fifth nerve to the level of the channel of Luschka. At the level of the sixth nerve nucleus, the hemorrhage had broken into the rourth ventricle. M icroscopicalfindings Microscopically, the gross lesion was a relatively recent hemorrhage. The left brain stem structures completely destroyed were as follows: at the level of the fifth nerve entry zone, the chief sensory nucleus of the Fig. 1 (see explanation in iexi). LATERAL INFERIOR PONTINE SYNDROME 319 Fig. 2 (see explanation in text). fifth nerve, and a portion of the middle cerebellar peduncle; at the level of the seventh nerve nucleus (Fig. 2), the fibers of the seventh and eighth nerves in their intramedullary course, the ventral and dorsal cochlear nuclei, the inferior cerebellar peduncle and a large portion of the middle cerebellar peduncle. At the rostral medulla, ventral and dorsal cochlear nuclei and the inferior cerebellar peduncle were destroyed. The remainder of the brain stem structures were preserved. CLINICO-PATHOLOGIC CORRELATIONS Bilateral or unilateral hearing loss in lesions of the pons or the midbrain is not uncommon (Haymaker 1968). Left-sided hearing loss in this case was clearly due to the destruction of the cochlear nuclei and of the eighth nerve fibers in their intramedullary course. The facial paralysis was due to the involvement of the intramedullary fibers of the seventh nerve alone, as the facial nucleus was preserved. It is of interest that vertigo was absent ; one would have expected this symptom to occur in view of the direct involvement of the eighth nerve. Vertigo has been aptly defined as a hallucination of motion due to the asynchronous activity of the two labyrinthine systems, functioning under normal circumstances in perfect accord (Leivers 1968). Bilateral loss of vestibular function does not result in vertigo which is seen after a unilateral vestibular lesion (Gernandt 1959). It is also known that secondary involvement of the inner ear often occurs as a complication of middle ear disease, usually inflammatory in nature (ScottBrown, Ballantyne and Graves 1965). It is probable that vestibular function had already been diminished in the right ear in our patient, due to such a cause. Thus, the sudden disruption of the left vestibular nerve by a hemorrhage resulted in little or no vertigo. The ataxia in the left extremities could be explained by the massive involvement of the left middle cerebellar peduncle and tile dentate nucleus, i.e. the cortico- "320 S. A L E K S I C , G , B U D Z I L O V I C H ponto-cerebellar system (Dow 1969). Loss of vestibular function must have played a significant role in causing the truncal ataxia. A marked influence of unilateral or bilateral vestibular lesions on equilibrium is well established (Gernandt 1959). The absence of mental changes or of alteration in the level of consciousness was probably due to the relatively caudal location of the lesion. Though the inferior extent of the brain stem structures critical to consciousness is not exactly known, it is probable that these do not extend below the level of entry of the fifth cranial nerve (Plum and Posner 1966). Nothing was found on general autopsy to account for the sudden death. The most probable final event was a sudden apnea. A pronounced influence on respiration of the tegmental pontine lesions, particularly of those situated dorsolaterally and caudally is well-established (Plum and Posner 1966). NOMENCLATURE OF THE BRAIN STEM VASCULAR LESIONS The use of an eponym or of the name of a superficial arterial blood vessel to designate the vascular syndromes of the brain stem is still prevalent in clinical practice, although the inadequacy of either approach has been emphasized (Gillilan 1964). Recent anatomic studies have shown that the intrinsic arterial vessels of the brain stem form distinct topographical zones; these are present essentially at all brain stem levels and each supplies a constant group of brain stem nuclei and structures with some relatively small overlap (Gillilan 1964). It has been found that the topography of brain stem vascular lesions in pathological material matches with a high degree of accuracy the distribution of the arterial zones described previously. As a result, a simple and accurate nomenclature of brain stem vascular syndromes has been suggested (Gillilan 1964). I --L-----I T---~--x . . . . . . L- Nucleii Body 2ochlear :leus I Nucleus & Tract I"1. }rnic (B') Corticobulbar Tracts Fig. 3 (explanationin text). LATERALINFERIOR PONTINESYNDROME 321 Accordingly, at the inferior pontine level one can recognize the medial inferior and lateral inferior pontine syndromes, or a combination thereof, in which case we suggest the term latero-medial inferior pontine syndrome (Fig. 3). The main clinical features of the lateral inferior pontine syndrome are involvement of the facial and, less constantly, the eighth nerve nuclei and/or of these nerves in their intramedullary course. The nuclei to the palato-pharyngeal muscles are spared; this distinguishes such cases from those of the lateral medullary syndrome. We have attempted to review briefly the pertinent literature in order to emphasize the usefulness and the accuracy of the nomenclature suggested by Gillilan. REVIEW OF LITERATURE There have been few cases reported so far of vascular accidents at the inferior pontine levels. In each of them there was clinical and/or pathological evidence of involvement of both the lateral and medial arterial zone. These were the cases of Foville (Wolf 1971), Millard-Gubler (Wolf 1971), Gelle (1901) and Hassin, Issacs and Gottle (1922). In our opinion all of them should be considered under the heading of the latero-medial inferior pontine syndrome. The case of Freeman, Ammerman and Stanley (1943) showed extensive involvement of the pontine and midbrain tegmentum and belongs more appropriately in the category of the basilar artery syndrome. The only well-documented case of the lateral inferior pontine syndrome reported thus far is that of Adams (1943) in which an infarct of the lateral pontine tegmentum and adjacent cerebellum due to an occlusion of the anterior inferior cerebellar artery was found at necropsy. Subsequently, this case served in the literature as a model for the syndrome of the anterior inferior cerebellar artery. However, variable symptoms following spontaneous (Goodhart and Davison 1936; Adams 1943) and iatrogenic (Atkinson 1949; House and Hitselberger 1968) occlusion of the anterior inferior cerebellar artery indicate clearly that its interruption does not result in any consistent clinical picture and that such a term should now be abandoned. SUMMARY A patient with left-sided deafness, left facial paralysis, sensory loss in the left side of the face and cerebellar signs of acute onset is presented. At necropsy, a circumscribed hemorrhage in the caudal pontine tegmentum and adjacent cerebellum was found. The clinical and pathological findings were those of the lateral inferior pontine syndrome. The pertinent literature is briefly reviewed and the use of topographical nomenclature is emphasized. REFERENCES ADAMS,R. D. (1943) Occlusion of the anterior inferior cerebellarartery, Arch. Neurol. Psychiat. (Chic.), 49 : 765-770. ATKINSON,W. J. (1949) The anterior inferior cerebellar artery. Its variations pontine distribution and significance in the surgery of the cerebello-pontineangle tumors, J. Neurol. Neurosur9. Psychiat.. 12: 137-152. 322 s. ALEKSIC, G. BUDZILOVICH Dow, R. (1969) Cerebellar syndromes. In: P. J. VINKENAND G. W. BRUYN(Eds.), Handbook o/Clinical Neurology, Vol. 2 (Localization in ClinicaI Neurology ), North-Holland Publishing Company, Amsterdam. Ch. 15, pp. 392 431. FREEMAN. W. R., H. AMMERMANAND M. STANLEY (1943) Syndromes of pontile tegmentum-Fovitle's syndrome, Arch. Neurol. Psychiat. (Chic.), 50: 462-471. GELLE, M. E. (1901) Paralysie alterne de l'acoustique, 16sign protuberantiel, C. R. Soc. Biol. (Paris). 53: 997-1000. GERNANDT, B. E. (1959) Vestibular mechanisms. In: J. FIELDet al. (Eds.), Handbook of Physiology, Sect. 1 (Neurophysiology), Vol. 1, Ch. 22, American Physiological Society, Williams and Wilkins, Baltimore, Md. GILLILAN, L. A. (1964) The correlation of the blood supply to the human brain stem with clinical brain stem lesions, J. Neuropath. exp. Neurol., 23: 78-108. GOODItART, S. P. ANDC. DAVISON(1936) Syndrome of the posterior inferior and anterior inferior cerebellar arteries and their branches, Arch. Neurol. Psychiat. (Chic.), 35: 501-524. HASSlN,G. B., H. ISSACSAND M. GOTTLE(1922) Clinical and pathologic report of a case ofpons hemorrhage (Type Foville), J. nerv. ment. Dis., 56:553 562. HAYMAKER,W. (1968) Bing's Local Diagnosis in Neurological Disease, Mosby, St. Louis, Mo., p. 210. HOUSE, W. E. AND W. E. HITSELBERGER (1968) Surgical complications of the acoustic tumor surgery, Arch. Otolaryng., 88:659 662. LEIVERS, E. (1968) Vertigo; an explanation-labyrinthine arythmia, Arch. Otolaryng., 88: 373-376. PLUM, F. AND J. POSWER(1966) The Diagnosis of Stupor and Coma, Davis, Philadelphia, Pa. SCOTT-BROWN, W. G., J. BALLANTYNEAND J. GRAVES(1965) Diseases of the Ear, Nose and Throat, Vol. 2, Butterworth, London, p. 483. WOLF, J. K. (1971) The Classical Brain Stern Syndromes. 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