BRIEF HISTORY: A 63 yrs old lady was brought in altered sensorium with complaints of diarrhea and vomiting of two days. Associated with complaints of giddiness, headache, abdomen pain and myalgia. Patient has no co morbid illness. Her blood pressure was 90/60 mm of Hg, pulse rate is 65 beats per min. Her hematological, biochemical, microbiological investigations were normal and patient was treated with uids and antibiotics as an acute gastroenteritis case and resolved. On rd3 day of admission, patient complaints of sudden onset of blurring of vision. On examination, it was identied as weak adduction on one side and abduction nystagmus on the contralateral eye. MRI brain was done and identied as lesion in the medial longitudinal fasciculus. DISCUSSION: The medial longitudinal fasciculus exists as a pair of tracts near the midline just under the fourth ventricle and cerebral aqueduct. It extends through the dorsomedial pontine and midbrain tegmentum. It is a heavily myelinated tract that allows conjugate eye movement by connecting the paramedian pontine reticular formation and abducens nucleus complex of the contralateral side to the oculomotor nucleus of the ipsilateral side. As it is proximal to the midline, more chances of bilateral injury. It primarily involves in coordinating synchronous horizontal moment and also regulates vertical pursuit, vertical vestibular signals and vertical alignment of two eyes. The major causes of internuclear ophthamoplegia are multiple sclerosis and cerebrovascular diseases. One third of the cases are caused by infection , trauma , tumour . ASSOCIATED SYNDROMES: WEBINO: Wall-Eyed Bilateral Internuclear Ophthalmoplegia exists when there is bilateral damage to the MLF. This damage causes a primary position exotropia (eyes are looking at the opposite “wall.”, thus the possibly outdated term “wall eyed”). The most common etiology is infarction of the midbrain in older patients and demyelinating disease in young patients.[3] The exotropia is likely decompensation of fusional mechanisms and the XT is not present in every case of bilat eral INO. WEMINO: This is a less common variant of INO, similar to the WEBINO above. As in WEBINO, patients with a unilateral MLF lesion (monocular INO) have a primary position XT. One and one half syndrome: This syndrome occurs when there is a lesion to the MLF and the PPRF or CN VI nucleus on the same side resulting in an INO in one eye and an ipsilateral horizontal gaze palsy EIGHT AND A HALF SYNDROME: This syndrome is characterized by having one-and-a-half syndrome and a facial fascicular nerve (CN VII) palsy. The fascicle of CN VII wraps around the nucleus of CN VI in the dorsal pons. There is conjugate horizontal gaze palsy on looking to one side followed by INO on looking to the opposite side, along with unilateral facial weakness. The close proximity of the PPRF, facial nerve nucleus and MLF located in the dorsal pons makes this syndrome much more likely. The lesion is most often vascular or demyelinating in the dorsal tegmentum of the caudal pons Half and Half Syndrome: A syndrome that consists of an INO CASE REPORT- A CASE OF INTERNUCLEAR OPHTHALMOPLEGIA AFTER BACTERIAL DIARRHEA Original Research Paper Dr. Kavuru Naga Siri Junior Resident Department Of General Medicine , Sree Balaji Medical College And Hospital General Medicine Internuclear ophthalmoplegia is a manifestation of intrinsic brain stem disease which produces ischemia of demyelination of nerve. The most common cause is multiple sclerosis and cerebrovascular diseases. Rare causes account for about 11%. Incidences are equal in males and females. It is extremely rare in pediatric population. We report a case of internuclear ophthalmoplegia following acute diarrheal episode. ABSTRACT KEYWORDS : Dr. Suresh Kanna* Assistant Professor Department Of General Medicine , Sree Balaji Medical College And Hospital *Corresponding Author VOLUME-9, ISSUE-1, JANUARY-2020 • PRINT ISSN No. 2277 - 8160 • DOI : 10.36106/gjra 18 X GJRA - GLOBAL JOURNAL FOR RESEARCH ANALYSIS in one eye combined with an ipsilateral CN VI fascicular involvement with sparing of the sixth nerve nucleus. Thus, there is “half” of a horizontal gaze palsy (INO) plus an additional “half” (abduction decit from CN VI fascicular palsy). POSTERIOR INO: This syndrome is a rare ophthalmoplegia, either bilateral or unilateral that exhibits contralateral adducting eye (rather than abducting eye) nystagmus with abduction restriction on physical exam. It is the reverse of the typical INO, and although the lesion localization is not consistent, it likely is due to CN VI pre-nuclear input asymmetry Partial third nerve palsy, other supranuclear gaze disturb ances, peripheral neuromusclular involvement are the differential diagnosis for this which can be elicited by a thorough clinical examination. The physical examination helps to arrive to the diagnosis An MRI brain is the key diagnostic factor for evaluation. Most patient will recover in days or months but in some , it still persists. CONCLUSION : Internuclear ophthalmoplegia is a disease with most common cause as multiple sclerosis but the frequency of other causes has also being increasing with similar prognosis. REFERENCES: 1. Cogan DG, Kubik CS, Smith WL. Unilateral internuclear ophthalmoplegia; report of 8 clinical cases with one postmortem study. AMA Arch Ophthalmol 1950;44:783-96. 2. Thömke F, Hopf HC, Krämer G. Internuclear ophthalmoplegia of abduction: Clinical and electrophysiological data on the existence of an abduction paresis of prenuclear origin. J Neurol Neurosurg Psychiatry 1992;55:105-11. 3. Ushio M, Iwasaki S, Chihara Y, Murofushi T. Wall-eyed bilateral internuclear ophthalmoplegia in a patient with progressive supranuclear palsy. J Neuroophthalmol 2008;28:93-6. 4. Fisher CM. Some neuro-ophthalmological observations. J Neurol Neurosurg Psychiatry 1967;30:383-92. 5. Eggenberger E. Eight-and-a-half syndrome: One-and-a-half syndrome plus cranial nerve VII palsy. J Neuroophthalmol 1998;18:114-6. 6. Xue F, Zhang L, Zhang L, Ying Z, Sha O, Ding Y, et al. One-and-a-half syndrome with its spectrum disorders. Quant Imaging Med Surg 2017;7:691- 7. 7. Rosini F, Pretegiani E, Guideri F, Cerase A, Rufa A. Eight and a half syndrome with hemiparesis and hemihypesthesia: The nine syndrome? J Stroke Cerebrovasc Dis 2013;22:e637 8. Mahale RR, Mehta A, John AA, Javali M, Abbas MM, Rangasetty S, et al. “Nine” syndrome: A new neuro-ophthalmologic syndrome: Report of two cases. Ann Indian Acad Neurol 2015;18:335-7 VOLUME-9, ISSUE-1, JANUARY-2020 • PRINT ISSN No. 2277 - 8160 • DOI : 10.36106/gjra X 19GJRA - GLOBAL JOURNAL FOR RESEARCH ANALYSIS