Unilateral Horizontal Gaze Palsy

Unilateral Horizontal Gaze Palsy; Esotropia; Fascilcular Sixth Nerve Palsy; Horizontal Gaze Evoked Nystagmus; Normal Convergence; Horizontal Oculocephalic Reflexes AbsentPowerPoint Presentation: Horizontal Gaze Palsy: http://library.med.utah.edu/NOVEL/Wray/PPT/Horizontal_Gaze_Palsy.ppt Shirley H. Wray, M.D., Ph.D., FRCP, Harvard Medical SchoolInability to look to the leftThis 56 year old woman with known adenocarcinoma of the breast presented with the recent onset of horizontal diplopia and deviation of her left eye inwards. Her oncologist referred her for a neuro-ophthalmic evaluation. This 56 year old woman with known adenocarcinoma of the breast presented with the recent onset of horizontal diplopia and deviation of her left eye inwards. Her oncologist referred her for a neuro-ophthalmic evaluation. Neuro-ophthalmological examination: Visual acuity, fields, pupils and fundi normal Ocular Motility: Unilateral horizontal gaze palsy to the left that impaired saccades and pursuit. Esotropia of the left eye Fascicular sixth nerve palsy Horizontal gaze full to the right, gaze evoked nystagmus Normal convergence, right eye induced to cross the midline Horizontal oculocephalic reflexes absent (Doll's head maneuver) Left lower motor neuron facial palsy (Bell's palsy) Neurological Exam: Normal The constellation of ocular motility signs together with a Bell's palsy localized the lesion to the left side of the pons at the level of the abducens nucleus. Differential Diagnosis: Pontine hemorrhage Pontine infarction Pontine tumor Brain CT: (Figures 1, 2) Demonstrated a focal pontine hemorrhage into a small brainstem metastasis. Bone Scan: Positive for multiple bone metastases. The patient was followed in the Neurovisual Clinic for several months. As she was one of the first patients to be scanned by computer tomography, she wished to donate her body to enable, at autopsy, a clinicopathological correlation of the brainstem lesion with CT imaging. Unfortunately, her family withheld their permission when she died. This case should be viewed alongside ID167-10, a patient with a unilateral horizontal gaze palsy and a pontine infarct.This patient with metastatic disease from CA breast had the following ocular motility signs: Unilateral horizontal gaze palsy to the left Esotropia of the left eye Fascicular sixth nerve palsy Horizontal gaze evoked nystagmus to the right Normal convergence Horizontal oculocephalic reflex absent (Doll's head maneuver) Leigh and Zee reported an almost identical case in their book(3). Their patient was a 52 year old woman with a right unilateral horizontal gaze palsy due to an ipsilateral pontine metastasis. The ocular motility signs were similar: • The patient was unable to move her eyes to the right past the midline using either saccadic or pursuit eye movements • Head rotation to the left, however, drove the eyes past the midline, but the right eye abducted incompletely • Vergence movements induced the left eye to cross the midline • Vertical eye movements were normal • Gaze evoked nystagmus was present on looking to the left, with slow phases toward the midline As her condition progressed, the patient developed a fascicular sixth nerve palsy. Leigh and Zee published a figure presenting a hypothetical explanation for their patient's horizontal gaze disorder and attributed it to involvement of the ipsilateral paramedial pontine reticular formation and the fascicles of the sixth nerve. Two important additional clinical signs in our patient aided localization. 1. A left Bell's palsy 2. Absent horizontal oculocephalic reflexes I attributed the unilateral horizontal gaze palsy to an ipsilateral lesion of the PPRF and the abducens nucleus. The Bell's palsy to involvement of the genu of the seventh cranial nerve as it loops over the abducens nucleus, and the esotropia to a fascicular sixth nerve palsy. (Figure 3 and 4 Brainstem control of horizontal gaze)Horizontal gaze palsy. There are four theoretical possibilities to account for the ipsilateral horizontal gaze palsy. It may be due to a single unilateral lesion affecting: 1. The ipsilateral paramedial pontine reticular formation (PPRF) only 2. The ipsilateral abducens nucleus alone 3. Both the ipsilateral paramedial pontine reticular formation (PPRF) and the abducens nucleus, or, when two lesions are involved 4. The motoneuron root fibers of the ipsilateral abducens nucleus to the lateral rectus and the contralateral medial longitudinal fasciculus (MLF). Paramedial pontine reticular formation. The medial portions of the nucleus reticularis magnocellularis (or nucleus centralis pontis oralis and caudalis) have been designated the "paramedian pontine reticular formation" (PPRF), rostral to the abducens nucleus. The region extends from the abducens nucleus in a rostral direction toward the brachium conjunctivum and trochlear nucleus. It has been defined functionally because there are no distinct histologic boundaries. But anatomically, Graybiel, Büttner-Ennever, and others all showed inputs from discrete areas. Clinical findings with PPRF lesion: • Loss of horizontal saccades towards the side of the lesion • Contralateral gaze deviation, in acute phase • Gaze-evoked nystagmus on looking contralateral to the lesion • Impaired smooth pursuit and vestibular eye movements may be preserved or impaired • Bilateral lesions cause total horizontal gaze palsy and slowing of vertical saccades Abducens nucleus. The abducens nucleus contains typical motoneurons that give rise to root fibers that innervate the lateral rectus as well as internuclear neurons whose axons cross the midline and ascend via the contralateral MLF to the medial rectus subnucleus in the contralateral oculomotor (third nerve) nucleus. This projection is the main excitatory input to medial rectus motoneurons in lateral gaze. An old clinicopathologic case published by Bennett and Savill (1) described a unilateral gaze palsy with an associated "patch of softening" in the abducens nucleus without apparent involvement of neighboring structures. Clinical findings with lesion of the abducens nuclei • Loss of all conjugate movements towards the side of the lesion - "ipsilateral, horizontal gaze palsy" • Contralateral gaze deviation, in acute phase • Vergence and vertical movements are spared • In the intact hemifield of gaze, horizontal movements may be preserved, but ipsilaterally directed saccades are slow • Horizontal gaze-evoked nystagmus on looking contralaterally • Ipsilateral lower motoneuron facial palsy often associated due to involvement of the genu of the seventh cranial nerve. The gustatory fibers are spared, because these fibers are carried in the intermediate branch of the facial nerve to the nucleus solitarius of the medulla. Damage to motor neurons, in the abducens nucleus innervating the left lateral rectus muscle or damage to the fascicular portion of the sixth nerve accounts for the ipsilateral sixth nerve palsy and esotropia. (Figure 3 and 4 Brainstem control of horizontal gaze) Clinical distinction PPRF: Abducens nucleus. At the bedside distinction can be made between the manifestations of gaze palsies in lesions of the PPRF in the upper pons from those of the PPRF in the lower pons at the level of the abducens nucleus. With PPRF lesions rostral to the abducens, there is ipsilateral paralysis of saccades and pursuit, but the eyes can be driven to the side of the gaze palsy with vestibular stimulation by the oculocephalic reflex and/or cold calorics. At the level of the abducens nucleus, lesions of the PPRF are associated with ipsilateral gaze palsy and loss of reflex vestibular (and tonic neck) movements. This presumes that there is a critical synapse within the caudal PPRF for the vestibulo-ocular pathways or that, at the very least, the functional integrity of the PPRF at that level is necessary for vestibulo-ocular eye movements. (Figure 5) Abducens nucleus and contralateral medial longitudinal fasciculus (MLF) An identical ipsilateral gaze palsy can be produced by damage to axons of abducens neurons as they course through the brainstem, namely, the ipsilateral sixth nerve fascicle and those axons which ascend the contralateral MLF. Separation of these two anatomic sites suggests two lesions. A lateral gaze palsy that always remains conjugate is consistent with one lesion of the abducens nucleus, whereas one that is not conjugate at any time would better fit two lesions.Brainstem metastasis from adenocarcinoma of the breastHemorrhage into a pontine metastasis1. Bronstein AM, Rudge P, Gresty MA, Du Boulay G, Morris J. Abnormalities of horizontal gaze. Clinical, oculographic and magnetic resonance imaging findings. II. Gaze palsy and internuclear ophthalmoplegia. J Neurol Neurosurg Psychiatry. 1990;53:200-207. http://www.ncbi.nlm.nih.gov/pubmed/2324752 2. Horn, AKE, Buttner-Ennever, JA, Buttner, U. Saccadic premotor neurons in the brainstem: functional neuroanatomy and clinical implications. Neuro-ophthalmology. 1996;16:229-240. 3. Leigh RJ, Zee DS. Diagnosis of Central Disorders of Ocular Motility. Chp 12;598-719. In: The Neurology of Eye Movements 4th Edition. Oxford University Press, New York, 2006 4. Meienberg, O, Buttner-Ennever, JA, Kraus-Ruppert, R. Unilateral paralysis of conjugate gaze due to lesion of the abducens nucleus. Neuro-ophthalmology. 1981;2:47-52. 5. Miller NR, Biousse V, Hwang T, Patel S, Newman NJ, Zee DS. Isolated acquired unilateral horizontal gaze paresis from a putative lesion of the abducens nucleus. J Neuroophthalmol. 2002;22:204-207. http://www.ncbi.nlm.nih.gov/pubmed/12352583 6. Müri RM, Chermann JF, Cohen L, Rivaud S, Pierrot-Deseilligny C. Ocular motor consequences of damage to the abducens nucleus area in humans. J Neuroophthalmol. 1996; 16:191-195. http://www.ncbi.nlm.nih.gov/pubmed/8865013 7. Oommen KJ, Smith MS, Labadie EL. Pontine hemorrhage causing Fisher one-and-a-half syndrome with facial paralysis. J Clin Neuroophthalmol. 1982;2:129-132. http://www.ncbi.nlm.nih.gov/pubmed/6226696 8. Pierrot-Deseilligny C, Chain F, Gray F, Escourolle R, Castaigne P. [Supranuclear lateral gaze palsy of pontine origin. Report of 2 clinicopathologic cases with electrooculographic and electromyographic data] Rev Neurol (Paris). 1979;135:741-762. http://www.ncbi.nlm.nih.gov/pubmed/555017MTemsphorizontalgazepalsy; MTnuclearcentersabducens; MTomnabducens; ICnuclearcenters; NOTE-EXAMgazepals