E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66.

Case Report

A rare case of cortical blindness - A case report

E.A. Ashok Kumar1*, Hanvitha Muppala2

1Professor, 2Post Graduate Department of General Medicine, Malla Reddy Institute of Medical Sciences, Hyderabad, India *Corresponding author email: [email protected]

International Archives of Integrated Medicine, Vol. 8, Issue 5, May, 2021. Available online at http://iaimjournal.com/ ISSN: 2394-0026 (P) ISSN: 2394-0034 (O) Received on: 14-04-2021 Accepted on: 21-04-2021 Source of support: Nil Conflict of interest: None declared. How to cite this article: E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66.

Abstract Cortical blindness refers to loss of vision caused by bilateral lesions with presence of intact anterior visual pathway. Neurological encompasses a broad spectrum of conditions. These include cerebral visual impairment, visual neglect, , various visual perceptual disorders, homonymous hemianopia, lack of facial recognition, delayed visual development and cortical blindness. Cortical blindness refers to loss of vision produced by lesions affecting geniculocalcarine visual pathways. Complete Cortical blindness is much less common than incomplete blindness. Cortical blindness is mostly due to cerebrovascular accident but also reported in pregnancy induced hypertensive , trauma, as result of MS exacerbation, post cardiac surgery, obstetric hemorrhage, MELAS, cerebral angiography, adrenoleukodystrophy, CNS angiitis and HIV-related progressive multifocal leukoencephalopathy. In this case report, we present a case of patient with cortical blindness due to bilateral occipital Infarcts.

Key words Cortical blindness, Bilateral occipital infarcts.

Introduction brain regions in which these are processed into The term “Cortical Blindness” describes the meaningful visual input such as brightness- partial or complete loss of vision resulting from a contrasts, colors, objects, faces. They are “blind” brain lesion. In this disorder there are no to the visual information that is not transmitted. ophthalmological causes and with normal pupillary light reflexes. With this type of visual Cortical Blindness can however also affect vision impairment the can be fully intact, but the in total; this requires damage to both sides of the visual information cannot be transmitted to the brain, usually due to bilateral lesions of the striate cortex in the occipital lobes [1]. Cortical

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E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66. blindness is a part of cerebral blindness which is Exact epidemiological data is not available. defined as loss of vision secondary to damage to Studies have shown a high incidence of cortical the visual pathways posterior to the lateral blindness in patients of cerebral in the geniculate nuclei [2]. With cortical blindness in range of 20 to 57% [8]. both halves of the visual field a person is really was the most common cause according to various completely blind, he/she cannot consciously studies, followed by surgery, particularly cardiac process visual input any longer, cannot identify surgery, and cerebral angiography [9]. or describe objects, cannot recognize faces, cannot read a text or reach for an item. Pathophysiology Knowledge of the visual pathway is important In the year 1895, Austrian neuropsychiatrist for the localization of lesions in cortical Gabriel Anton described patients with bilateral blindness. In cortical blindness, lesion lies in the occipital lobe lesions, who were completely blind striate cortex, and often the nearby areas of the but were unaware of their blindness leading to brain are also involved. confabulation [3]. Visual pathway Etiology The is the starting point of the optic Cortical blindness can affect both children and nerve. The optic disc does not contain any visual adults. In children, common causes include; receptors. It is the physiological blind spot. Congenital abnormalities of the occipital lobe, Fibers from the temporal Half of are cardiac arrest, , or situated in the lateral half i.e. temporal half of the perinatal asphyxia, cerebral infarction, while fibers from the nasal half of , , subacute sclerosing retina are situated in the medial half i.e. nasal leukoencephalitis, hypoglycemia, uremia, half. Similarly, upper retinal fibers are present , shunt malfunction, head trauma, superiorly and lower fibers are present inferiorly cardiac surgery, cerebral or vertebral in the optic nerve. The optic nerve extends from angiography , drugs (i.e., cyclosporin A and the retina to the optic chiasm and the length is steroids), acute carbon monoxide poisoning, and about 5 cm. It is conventionally divided into four the ictal state in occipital lobe or portions- intraocular, intraorbital, postictal phenomenon [4]. intracanalicular, and intracranial.

In adults, it is seen in lesions of the primary The optic nerve is covered by the layers of of the occipital lobes secondary to meninges. The intraocular part is the optic disc multiple disorders including; Stroke, Cardiac wherefrom the intraorbital portion starts leading embolism, Head trauma, Occipital lobe epilepsy, to the intracanalicular portion as the nerve Hyponatremia, Severe hypoglycaemia, traverses the optic canal. Then the two optic Creutzfeldt-Jacob disease, Infection e.g. HIV, nerve exit from the optic canals and form the , MELAS (mitochondrial myopathy, optic chiasm where temporal hemiretinal fibers encephalopathy, lactic acidosis, and stroke-like continue ipsilaterally and nasal hemiretinal fibers episodes),cardiac surgery, cerebral angiography, decussate and join the opposite optic tract. The IV contrast medium. Rarely, transient cortical tracts extend from the chiasm to the lateral blindness can be caused by Infective endocarditis geniculate body (LGB). Afferent fibers from the or Hypertensive encephalopathy, Posterior leave the tract just anterior to the LGB. The reversible encephalopathy syndrome (PRES) [5, visual afferents synapse in the LGB and second- 6, 7]. order neuron starts as geniculocalcarine pathways (optic radiation) and terminate in the Epidemiology calcarine cortex of the occipital lobe. The primary visual cortex (V1) lies in the

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E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66.

Brodmann’s Area 17. Area 18 (V2) also known majority of cases, however, central vision, as the parastriate or parareceptive area, receives including the foveal representation, remains and interprets impulses from Area 17. The intact because of the blood supply of the peristriate or perireceptive cortex, Area 19 (V3, occipital pole. The fovea is generally represented V4, V5) has connections with Areas 17, 18, and in the occipital pole and it receives its blood with other portions of cortex. supply from the middle cerebral artery along with the branches of the posterior cerebral artery. The anterior choroidal artery and Because of this dual blood supply, stroke causing thalamoperforators from the posterior cerebral the complete destruction of V1 is extremely rare. artery (PCA) supply the optic tract. Optic This preservation of central vision is very radiation is supplied by the middle cerebral important for rehabilitation. Another peculiarity artery (MCA) and the occipital lobe is primarily that can be seen in Cortical blindness patients is supplied by the PCA. The occipital lobe also 'blind sight' where an individual can perceive receives supply from the MCA. coarse flickering movement in the blind field. This is due to preserved unconscious visual History and physical examination processing abilities in the individuals because of To make a proper diagnosis and to determine the the heterogeneity of damage to V1. Other aetiology of Cortical blindness, proper history features of visual cortex lesion include Anton should be elicited, like birth history, antenatal syndrome, Riddoch phenomenon, and formed history, addictions, drug history, hypertension, visual . diabetes, palpitation, fever and any history of head trauma. A complete neurological and Anton syndrome: It is also known as visual ophthalmological examination should be done. anosognosia when a person cannot see but An important thing to remember is that pupillary always denies the blindness even with clear light reflex remains intact in cortical blindness, evidence of blindness. These individuals often and extraocular movements will be normal. try to walk through the closed door or wall and in There is no relative afferent pupil defect (RAPD) the process of denial they take help of in cortical blindness. confabulation. It occurs due to lesions in the V1.

There may be clinical features depending on the Riddoch phenomenon: This is also known as location of the lesion. Lesion in temporal lobe statokinetic dissociation. Here patients can only causes acute disturbance in memory, particularly perceive moving objects in the blind field, not if it affects the dominant lobe. Posterior cerebral the static ones [12]. Patients may not perceive artery occlusion may produce visual color or details of the moving objects except the hallucinations of brightly colored scenes and movement. This syndrome is often seen in objects (peduncular hallucinosis) due to damage lesions of the occipital lobe. The to the thalami, brainstem [10]. Left-sided large pathophysiology of Riddoch syndrome due to PCA stroke can produce visual agnosia due to occipital lobe disease is thought to involve visual disconnection between language and visual inputs reaching the V5 (motion processing systems whereas right-sided stroke can produce cortex) bypassing the V1 area, leading to a due to involvement of the inferior conscious awareness of motion within a blind occipital areas, fusiform gyrus, and the anterior field. temporal cortex [11]. Benson syndrome: Also known as posterior Depending on the extent of the damage to V1, cortical atrophy, is a form of atypical the loss of vision varies between a small Alzheimer’s disease [13]. It was first described about the size of the blind spot, a by Dr. DF Benson in 1988 [14]. Here patient , and full hemianopia. In the shows a decrease in visuospatial and

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E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66. visuoperceptual capabilities but language, Differential diagnoses learning and cognition remain intact in the early Differential diagnoses of cortical blindness are: stages [15]. Here the damage lies in the occipital Hemineglect, Prosopagnosia, Simultagnosia, cortex and associated areas of temporal and Malingering parietal lobe which can be viewed in MRI (magnetic resonance imaging) brain. Prognosis Prognosis depends on the severity of the damage Posterior reversible encephalopathy syndrome to the visual cortex. Extensive bilateral occipital (PRES): PRES presents with acute onset lesions have a worse prognosis than transient , , altered consciousness, and ischemic attacks. Sometimes with extensive visual disturbance [16]. It is usually seen in training and tasks patients can achieve some association with malignant hypertension, aspects of visual performance matching the intact eclampsia. Typical MRI brain findings are of hemifield vision, but full recovery of vision in all bilateral white-matter abnormalities in vascular aspects doesn't occur after damage to the V1 area watershed areas affecting mostly the occipital [23]. Prognosis also depended on the cause of and parietal lobes [16, 17, 18]. With proper Cortical blindness and proved to be much better management of hypertension and other in patients with Cortical blindness following associated risk factors, PRES can be completely surgery or cerebral angiography, than following a reversed including the MRI findings. stroke [24, 25]. Order in which vision was recovered: light, motion, form, color, central and, Balint syndrome: Austro-Hungarian neurologist finally, peripheral vision [26]. and psychiatrist R Balint first described it [19]. It is characterized by simultanagnosia, oculomotor Complications apraxia, and optic ataxia. Lesion lies in the Cortical blindness causes a great amount of bilateral parietal lobes and in some cases morbidity to the patients. Their daily life gets occipital lobe [20]. hampered. Family members of the patient, are also get affected by this. Cortical blindness leads Treatment and management to a socioeconomic burden. The patients may be Apart from standard management of the cause more prone to falls and fractures. which in most cases is stroke, the major part of treatment is visual training and rehabilitation. Case report A 60 year old female admitted to the hospital, Three common modes of interventions are 1) with complaints of painless loss of vision in both restitution therapy, 2) compensation therapy, and eyes and slurring of speech of 4 days duration. 3) substitution therapy. No history of head injury, headache, vomiting, 1) Restitution therapy is done to recover visual giddiness, loss of consciousness, weakness of field deficits. It is like the perimetry [21]. Here, limbs, loss of sensations, double vision, difficulty the patient detects multiple light spots on a black in swallowing, difficulty in chewing, urinary and screen across blind and normal visual hemifield. fecal incontinence. 2) Compensation therapy acts by compensating for visual loss by saccadic movements Past history: Patient has history of left [22]. It helps to capture visual stimuli that would hemiparesis – 2 years ago, for which she took otherwise fall onto the blind part of the visual treatment and recovered. Patient was a known field. case of NIDDM since 3 years and is on treatment 3) On the other hand, substitution therapy uses for the same. No history of Asthma, HTN, TB, prism or other devices to project the visual thyroid disorder, epilepsy, CRHD, MI or stimulus from the blind side of the visual field to bleeding tendency. the normal one [22].

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E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66.

No significant family history. Menstrual history: 2%, Platelet count – 2.4 lakhs/cu mm. ESR 1st hr attained menopause 5 years ago. - 20 mm, Blood Urea 24 mg%, Serum Creatinine - 0.6 mg, Complete Urine General Examination: Patient was conscious, Examination (CUE) – Albumin-Nil, Sugar-Nil, Incoherent, with Confused Conversation. Random Blood Sugar of 300 mg/dl, Serum Moderately Built, Moderately Nourished. No Electrolytes: Na – 139 m mol/L, K – 4.3 m Icterus, Cyanosis, Clubbing, Koilonychias, mol/L, CL – 105 m mol/L. LFT – Normal, Lymphadenopathy, Pedal Edema. No Neuro Fasting Lipid Profile-WNL, USG Abdomen- Cutaneous Markers. No peripheral nerve NAD, HIV- Non reactive, HbsAg- Negative, thickening. No trophic ulcers. Head & Spine = HBC- Negative, X-ray Chest PA view- NAD, Normal. No Tenderness. Thyroid = Normal. ECG- Q++ in L1 and L2, CT scan brain (Figure - 1) showed: Bil. occipital lobe infarcts, EEG and Vitals: Temp- Normal, PR =90/min, regular. BP VEP was not done. =130/80 mm of Hg. RR=18/min A diagnosis of CVA – C.Thrombosis in both CNS examination: Patient was conscious, PCA territories with bilateral cortical blindness Incoherent, with Confused Conversation, Rt. & and old Rt.MCA territory thrombosis with Handed, not oriented in time & place, Memory – Lt.hemiparesis was made. Decreased, Speech – Dysarthria +. Optic Nerve – Treatment given No Light Perception In Both Eyes. – Both 1. Inj MANNITOL 10% 100 ml iv TID sides 3 mm, reacting To Light accomodation 2. Inj AMPICILLIN 500mg iv QID reflex absent - Facial Nerve-Lt. UMN Facial 3. Inj. AMIKACIN 500 mg iv BD Palsy +. Other CN – Normal. 4. INJ. ACTRAPID 6 UNITS S/C TID 5. Diabetic Diet MOTOR SYSTEM EXAMINATION of Right 6. TAB.ECOSPRIN 75 MG sided limbs was normal. Left sided limbs 7. Inj OPTINEURON 1 amp iv OD revealed- Bulk- Normal, tone- hypotonia, Power- 8. I.V.Fluids 4/5. Superficial Reflexes = Normal. Corneal & 9. Physiotherapy Conjunctival – Present on both sides. Abdominals- Present, Plantars- Extensor on both Discussion sides.DTR – exaggerated on lt.side, Co – Cortical blindness is rare; mostly described the ordination & gait- swaying towards Lt.side. condition in vascular pathologies. Visual anosognosia was most commonly associated with SENSORY SYSTEM EXAMINATION: Pain, occipital infarcts. Other vascular cases of visual Temperature normal in all limbs. Pressure, anosognosia were in the setting of post Vibration, Joint sensations normal in all the pregnancy reversible cerebrovascular syndrome, limbs. Fundus – Both Eyes Immature systemic angiitis, and hypovolemic shock. The ++ media clear, Fundus - Pale & No syndrome has also been reported in association Papilloedema. No signs of Meningeal Irritation. with 6 other conditions: progressive multifocal Skull & Spine – Normal. Examination of leukoencephalopathy in the setting of HIV, Cardiovascular and Respiratory Systems was adrenoleukodystrophy, bisynchronous occipital normal. seizures, mitochondrial encephalopathy and lactic acidosis. Visual evoked potentials (VEPs) Investigations - Hb-10.4 g%, RBC count 7.2 may have been helpful to support this theory, but mill/cumm, WBC count 8600 cells/cumm with were not obtained [27]. Neutrophils - 72%, Lymphocytes - 24%, Eosinophils - 2%, Basophils - 0%, Monocytes -

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E.A. Ashok Kumar, Hanvitha Muppala. A rare case of cortical blindness - A case report. IAIM, 2021; 8(5): 59-66.

Figure – 1: CT SCAN Axial Sections – Revealed bil. occipital lobe infarcts.

Although stroke remains the most common cause history of general atherosclerosis or history of of Cortical blindness, surgery, especially cardiac vertebro-basilar transient ischaemic attacks. The surgery, and cerebral angiography are now onset of blindness is sudden; characteristically frequent causes. Cardiac surgery, which was patients exhibit no other neurological signs. The rarely performed three decades ago, may cause eyes are still able to move through a full range, cerebral dysfunction through a variety of but optokinetic cannot be elicited. mechanisms, including anoxia from Visual imagination and visual imaginary dreams hypoperfusion, cerebral hemorrhage, and blood, are preserved. With very rare exception no fat, and air embolism. Ischemic neuronal damage cortical potential can be evoked in the occipital of the calcarine cortex is frequent in patients who lobes with light flashes or pattern changes. The do not survive heart surgery. alpha rhythm is lost in EEG. A striking feature of patients with cortical blindness is subjective The most common cause of cortical blindness is unawareness of ones disability (anosognosia). occlusion of the posterior cerebral arteries The other less common symptoms include visual (embolic or thrombus). Hypoxic-ischaemic hallucinations due to cortical irritation, encephalopathy; Progressive multifocal associated apathy and mental disturbances. leucoencephalopathy. Other leucodystrophies Rarely, oval pupils have been reported with and bilateral gliomas are other causes. Bilateral bilateral cerebral infarctions. A large embolus in occipital lobe infarction though extremely rare the basilar artery is usually fatal [28]. can occur due to thrombosis or embolism affecting the vertebro basilar system of vessels Conclusion usually triggered off by fall in the blood pressure. A diagnosis of CVA – C. Thrombosis in both When the terminal bifurcation of basilar artery is PCA territories with bilateral cortical blindness involved the symptoms may be bilateral. & and old Rt.MCA territory thrombosis with Lt. Melamed and Abraham reported three similar hemiparesis was made. EEG and VEP was not cases. In all the cases clinical and angiographic done. Cortical blindness is rare; mostly described evidence of basilar artery occlusion was seen. the condition in vascular pathologies. Hence this These patients are generally in their sixties with a case report. The most common cause of cortical

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