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Baguma M, Nzabara F, Maheshe Balemba G, Malembaka EB, Migabo C, Mudumbi G, Bito V, Cliff J, Rigo JM, Chabwine JN. Konzo risk factors, determinants and etiopathogenesis: What is new? A systematic review. Neurotoxicology 2021; 85:54-67. [PMID: 33964344 DOI: 10.1016/j.neuro.2021.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/01/2021] [Accepted: 05/03/2021] [Indexed: 12/13/2022]
Abstract
Konzo is a toxico-nutritional upper motor neuron disease causing a spastic paraparesis in schoolchildren and childbearing women in some African countries. Almost a century since the first description of konzo, its underlying etiopathogenic mechanisms and causative agent remain unknown. This paper aims at refreshing the current knowledge of konzo determinants and pathogenesis in order to enlighten potential new research and management perspectives. Literature research was performed in PubMed and Web of Science databases according to the PRISMA methodology. Available data show that cassava-derived cyanide poisoning and protein malnutrition constitute two well-documented risk factors of konzo. However, observational studies have failed to demonstrate the causal relationship between konzo and cyanide poisoning. Thiocyanate, the current marker of choice of cyanide exposure, may underestimate the actual level of cyanide poisoning in konzo patients as a larger amount of cyanide is detoxified via other unusual pathways in the context of protein malnutrition characterizing these patients. Furthermore, the appearance of konzo may be the consequence of the interplay of several factors including cyanide metabolites, nutritional deficiencies, psycho-emotional and geo-environmental factors, resulting in pathophysiologic phenomena such as excitotoxicity or oxidative stress, responsible for neuronal damage that takes place at sparse cellular and/or subcellular levels.
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Affiliation(s)
- Marius Baguma
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium.
| | - Fabrice Nzabara
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; École Régionale de Santé Publique (ERSP), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Ghislain Maheshe Balemba
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Espoir Bwenge Malembaka
- École Régionale de Santé Publique (ERSP), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Christiane Migabo
- Faculty of Agronomy, Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Department of Geography and Environmental Studies, College of Social Sciences and Humanities, Jimma University, Jimma, Ethiopia
| | - Germain Mudumbi
- Department of Pediatrics, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Virginie Bito
- Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium
| | - Julie Cliff
- Faculty of Medicine, Department of Community Health, Eduardo Mondlane University, Maputo, Mozambique
| | - Jean-Michel Rigo
- Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium
| | - Joëlle Nsimire Chabwine
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Department of Neuroscience and Movement Science, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
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Plants with neurotoxic potential in undernourished subjects. Rev Neurol (Paris) 2019; 175:631-640. [DOI: 10.1016/j.neurol.2019.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 12/20/2022]
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Kashala-Abotnes E, Okitundu D, Mumba D, Boivin MJ, Tylleskär T, Tshala-Katumbay D. Konzo: a distinct neurological disease associated with food (cassava) cyanogenic poisoning. Brain Res Bull 2018; 145:87-91. [PMID: 29981837 DOI: 10.1016/j.brainresbull.2018.07.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/18/2018] [Accepted: 07/04/2018] [Indexed: 10/28/2022]
Abstract
Epidemics of neurodegenerative diseases putatively caused by food toxins have been reported in the tropics with no clear understanding of their pathogenetic mechanisms. These diseases include the disease named Konzo that has been well documented in sub-Sahara Africa, mostly among children and women of childbearing age. Outbreaks of Konzo have occurred in the Democratic Republic of Congo, Mozambique, Tanzania, Central African Republic, Angola, Cameroun, and most recently in Zambia. The main clinical picture consists of a symmetrical, permanent and irreversible spastic paraparesis (motor neuron disease) with no signs of sensory or genitourinary impairments. Recently, cognitive impairments and neurodevelopmental delays have been reported among school-aged and very young children. The exact pathogenetic mechanisms of the disease remain unknown. Epidemiological studies consistently show an association between outbreaks of the disease and chronic dietary reliance on insufficiently processed cyanogenic cassava (manioc or tapioca). Biochemical and toxicological studies suggest that the metabolites of linamarin (α-Hydroxyisobutyronitrile β-D-glucopyranoside, the main cassava cyanogen), notably cyanide (mitochondrial toxin), thiocyanate (AMPA chaotropic agent), and cyanate (protein carbamoylating agent) may play an important role in the pathogenesis of Konzo. Experimental data suggest that thiol-redox and protein- folding mechanisms may also be perturbed. Factors of susceptibility including genetics, poor nutrition, poverty and dietary cyanogen exposure, or their interactions have been suggested. Serological studies have ruled out the role of retroviruses such as the human lymphotropic viruses HIV-I/II or HTLV-I/II. Because there is no cure for Konzo, prevention of the disease remains of paramount importance. Prospects for cognitive rehabilitation still need to be explored and tested.
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Affiliation(s)
| | - Daniel Okitundu
- Department of Neurology, University of Kinshasa, Democratic Republic of Congo
| | - Dieudonne Mumba
- Department of Tropical Medicine, University of Kinshasa & National Institute of Biomedical Research (INRB), Democratic Republic of Congo
| | - Michael J Boivin
- Departments of Psychiatry and Neurology & Ophthalmology, Michigan State University, East Lansing MI, USA; Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Thorkild Tylleskär
- Department of Global Public Health and Primary Care, University of Bergen, Norway
| | - Desire Tshala-Katumbay
- Department of Neurology, University of Kinshasa, Democratic Republic of Congo; Department of Tropical Medicine, University of Kinshasa & National Institute of Biomedical Research (INRB), Democratic Republic of Congo; Department of Neurology & School of Public Health, Oregon Health & Science University, Portland OR, USA
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Newton CR. Cassava, konzo, and neurotoxicity. LANCET GLOBAL HEALTH 2018; 5:e853-e854. [PMID: 28807173 PMCID: PMC6995356 DOI: 10.1016/s2214-109x(17)30306-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 12/28/2022]
Affiliation(s)
- Charles R Newton
- Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK; Kenya Medical Research Institute-Wellcome Trust Collaborative Programme, Kilifi, Kenya.
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Tshala-Katumbay DD, Ngombe NN, Okitundu D, David L, Westaway SK, Boivin MJ, Mumba ND, Banea JP. Cyanide and the human brain: perspectives from a model of food (cassava) poisoning. Ann N Y Acad Sci 2016; 1378:50-57. [PMID: 27450775 DOI: 10.1111/nyas.13159] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/29/2016] [Accepted: 06/01/2016] [Indexed: 11/26/2022]
Abstract
Threats by fundamentalist leaders to use chemical weapons have resulted in renewed interest in cyanide toxicity. Relevant insights may be gained from studies on cyanide mass intoxication in populations relying on cyanogenic cassava as the main source of food. In these populations, sublethal concentrations (up to 80 μmol/l) of cyanide in the blood are commonplace and lead to signs of acute toxicity. Long-term toxicity signs include a distinct and irreversible spastic paralysis, known as konzo, and cognition deficits, mainly in sequential processing (visual-spatial analysis) domains. Toxic culprits include cyanide (mitochondrial toxicant), thiocyanate (AMPA-receptor chaotropic cyanide metabolite), cyanate (protein-carbamoylating cyanide metabolite), and 2-iminothiazolidine-4-carboxylic acid (seizure inducer). Factors of susceptibility include younger age, female gender, protein-deficient diet, and, possibly, the gut functional metagenome. The existence of uniquely exposed and neurologically affected populations offers invaluable research opportunities to develop a comprehensive understanding of cyanide toxicity and test or validate point-of-care diagnostic tools and treatment options to be included in preparedness kits in response to cyanide-related threats.
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Affiliation(s)
- Desire D Tshala-Katumbay
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon. .,Department of Neurology, University of Kinshasa, Kinshasa, Congo. .,National Nutrition Program, Ministry of Health, and Kinshasa School of Public Health, Kinshasa, Congo.
| | | | - Daniel Okitundu
- Department of Neurology, University of Kinshasa, Kinshasa, Congo
| | - Larry David
- Department of Biochemistry and Proteomic Share Resource, Oregon Health & Science University, Portland, Oregon
| | - Shawn K Westaway
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Michael J Boivin
- Department of Psychiatry and Neurology/Ophthalmology, Michigan State University, East Lansing, Michigan
| | - Ngoyi D Mumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Congo.,Institut National de Recherches Biomédicales (INRB), Kinshasa, Congo
| | - Jean-Pierre Banea
- National Nutrition Program, Ministry of Health, and Kinshasa School of Public Health, Kinshasa, Congo
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Bumoko GM, Sombo MT, Okitundu LD, Mumba DN, Kazadi KT, Tamfum-Muyembe JJ, Lasarev MR, Boivin MJ, Banea JP, Tshala-Katumbay DD. Determinants of cognitive performance in children relying on cyanogenic cassava as staple food. Metab Brain Dis 2014; 29:359-66. [PMID: 24481810 PMCID: PMC4024334 DOI: 10.1007/s11011-014-9492-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 01/20/2014] [Indexed: 10/25/2022]
Abstract
While risk factors for konzo are known, determinants of cognitive impairment in konzo-affected children remain unknown. We anchored cognitive performance (KABC-II scores) to serum levels of free-thyroxine (free-T4), thyroid-stimulating hormone (TSH), albumin, and motor proficiency (BOT-2 scores) in 40 children including 21 with konzo (median age: 9 years) and 19 without konzo (median age: 8 years). A multiple regression model was used to determine variables associated with changes in KABC-II scores. Age (β: -0.818, 95% CI: -1.48, -0.152) (p = 0.018), gender (β: -5.72; 95% CI: -9.87, -1.57 for females) (p = 0.009), BOT-2 score (β: 0.390; 95% CI: 0.113, 0.667) (p = 0.008), and free-T4 (β: 1.88; 95% CI: 0.009, 3.74) (p = 0.049) explained 61.1 % of variation in KABC-II scores. Subclinical hypothyroidism was not associated with poor cognition. A crude association was found between serum albumin and KABC-II scores (β: 1.26; 95 % CI: 0.136, 2.39) (p = 0.029). On spot urinary thiocyanate reached 688 μmol/l in children without konzo and 1,032 μmol/L in those with konzo. Female gender and low serum albumin are risk factors common to cognitive and proportionally associated motor deficits in children exposed to cassava cyanogens. The two types of deficits may share common mechanisms.
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Affiliation(s)
- G M Bumoko
- Department of Neurology, University of Kinshasa, Kinshasa, Congo
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Boivin MJ, Okitundu D, Makila-Mabe Bumoko G, Sombo MT, Mumba D, Tylleskar T, Page CF, Tamfum Muyembe JJ, Tshala-Katumbay D. Neuropsychological effects of konzo: a neuromotor disease associated with poorly processed cassava. Pediatrics 2013; 131:e1231-9. [PMID: 23530166 PMCID: PMC3608487 DOI: 10.1542/peds.2012-3011] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Konzo is an irreversible upper-motor neuron disorder affecting children dependent on bitter cassava for food. Although the neuroepidemiology of konzo is well characterized, we report the first neuropsychological findings. METHOD Children with konzo in the Democratic Republic of Congo (mean age 8.7 years) were compared with children without konzo (mean age 9.1 years) on the Kaufman Assessment Battery for Children, second edition (KABC-II), and the Bruininks-Oseretsky Test of Motor Proficiency, second edition (BOT-2). Both groups were also compared with normative KABC measures from earlier studies in a nearby nonkonzo region. RESULTS Using a Kruskal-Wallis test, children with konzo did worse on the KABC-II simultaneous processing (visual-spatial analysis) (K [1] = 8.78, P = .003) and mental processing index (MPI) (K [1] = 4.56, P = .03) than children without konzo. Both konzo and nonkonzo groups had poorer KABC sequential processing (memory) and MPI relative to the normative group from a nonkonzo region (K [2] = 75.55, P < .001). Children with konzo were lower on BOT-2 total (K [1] = 83.26, P < .001). KABC-II MPI and BOT-2 total were predictive of konzo status in a binary logistic regression model: odds ratio = 1.41, P < .013; 95% confidence interval 1.13-1.69. CONCLUSIONS Motor proficiency is dramatically affected, and both children with and without konzo have impaired neurocognition compared with control children from a nonoutbreak area. This may evidence a subclinical neurocognitive form of the disease, extending the human burden of konzo with dramatic public health implications.
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Affiliation(s)
| | | | | | | | - Dieudonne Mumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo;,Institut National de Recherches Biomédicales, Kinshasa, Democratic Republic of Congo
| | - Thorkild Tylleskar
- Center for International Health, University of Bergen, Bergen, Norway; and
| | - Connie F. Page
- Department of Statistics and Probability, Michigan State University, East Lansing, Michigan
| | - Jean-Jacques Tamfum Muyembe
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo;,Institut National de Recherches Biomédicales, Kinshasa, Democratic Republic of Congo
| | - Desire Tshala-Katumbay
- Department of Neurology, and,Department of Neurology and Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, Oregon
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Adamolekun B. Neurological disorders associated with cassava diet: a review of putative etiological mechanisms. Metab Brain Dis 2011; 26:79-85. [PMID: 21327546 DOI: 10.1007/s11011-011-9237-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 02/02/2011] [Indexed: 10/18/2022]
Abstract
Tropical ataxic neuropathy (TAN) and epidemic spastic paraparesis (konzo) are two neurological disorders associated with the consumption of cassava (Manihot esculenta) in several African countries. TAN is characterized by sensory polyneuropathy, sensory ataxia, bilateral optic atrophy and bilateral sensori-neural deafness. It occurs in elderly individuals subsisting on a monotonous cassava diet with minimal protein supplementation. Konzo is a syndrome of symmetrical spastic paraparesis with a predilection for children and young women and invariably associated with consumption of inadequately processed bitter cassava roots with minimal protein supplementation. Despite numerous epidemiological, clinical and biochemical studies aimed at elucidating the etiological mechanisms of these disorders, their etiologies remain unknown, and there is no known treatment. The diseases continue to be prevalent in endemic areas, causing significant disability and increased mortality. A fresh appraisal of the putative etiologic mechanisms proposed for these intriguing and enigmatic syndromes is presented in this paper. Evidences against a causal role for cyanide intoxication are discussed, and evidences implicating thiamine deficiency as a unifying etiological mechanism for these neurological syndromes are presented. It is concluded that urgent research is needed to evaluate thiamine status and implement a therapeutic trial of thiamine in these debilitating neurological disorders.
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Affiliation(s)
- Bola Adamolekun
- Department of Neurology, University of Tennessee Health Science Center, 855 Monroe Avenue, Memphis, TN 38163, USA.
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Adamolekun B. Etiology of Konzo, epidemic spastic paraparesis associated with cyanogenic glycosides in cassava: Role of thiamine deficiency? J Neurol Sci 2010; 296:30-3. [DOI: 10.1016/j.jns.2010.06.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/25/2010] [Accepted: 06/16/2010] [Indexed: 11/17/2022]
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Chapter 18 Toxic disorders of the upper motor neuron system. HANDBOOK OF CLINICAL NEUROLOGY 2007; 82:353-72. [DOI: 10.1016/s0072-9752(07)80021-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Mwanza JC, Lysebo DE, Kayembe DL, Tshala-Katumbay D, Nyamabo LK, Tylleskär T, Plant GT. Visual Evoked Potentials in Konzo, a Spastic Paraparesis of Acute Onset in Africa. Ophthalmologica 2003; 217:381-6. [PMID: 14573969 DOI: 10.1159/000073066] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Accepted: 05/23/2003] [Indexed: 11/19/2022]
Abstract
AIM To assess whether or not visual evoked potentials (VEPs) are abnormal in konzo, a para/tetraparesis of sudden onset, and to correlate the findings to the clinical picture of the disorder. METHODS VEPs were recorded in 23 patients (9 men and 14 women, mean age: 23 +/- 10 years) suffering from konzo, and 38 healthy subjects (20 men and 18 women, mean age: 27 +/- 15 years). The mean P100 latencies and peak-to-peak N75-P100 amplitudes of each eye were measured and compared in the two groups. The mean interocular P100 latency and amplitude differences were calculated and also compared. RESULTS VEPs were abnormal in 11/23 patients (48%) consisting of P100 prolongation (7 subjects), absence of P100 wave (2 subjects) or an atypical waveform (2 subjects). The mean P100 latency value of the konzo group was significantly increased as compared with the mean (+ 2.5 SD) of the reference values from healthy subjects (p < 0.05). There was a statistically significant decrease of amplitude in konzo patients compared to normal subjects (p < 0.05) with, however, only 2 patients outside the 95% confidence limits. Six patients (27%) had abnormal VEPs despite normal visual acuity. These abnormalities were symmetric and a relation could be found between neither the duration nor the severity of the disease and the VEP perturbation. CONCLUSION The main features of these abnormalities are delayed P100 latency and decreased amplitude. These findings indicate involvement of visual pathways and seem to suggest the presence of axonal loss in the prechiasmal visual pathways in konzo. This study provides evidence that the neurodamage in konzo extends to the visual pathways.
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Affiliation(s)
- J-C Mwanza
- Department of Ophthalmology, Kinshasa University Hospital, Kinshasa, Democratic Republic of Congo.
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Mwanza JCK, Tshala-Katumbay D, Kayembe DL, Eeg-Olofsson KE, Tylleskär T. Neuro-ophthalmologic findings in konzo, an upper motor neuron disorder in Africa. Eur J Ophthalmol 2003; 13:383-9. [PMID: 12872796 DOI: 10.1177/112067210301300409] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE To investigate the neuro-ophthalmological manifestations in konzo, a non-progressive symmetric spastic para/tetraparesis of acute onset associated with consumption of insufficiently processed bitter cassava roots combined with a low protein intake. METHODS Twenty-one Congolese konzo patients underwent neuro-ophthalmological investigations including visual acuity testing, assessment of light pupillary reflexes, evaluation of ocular motility and deviation, direct ophthalmoscopy, and visual field perimetry. Objective refraction including retinoscopy and keratometry, and slit-lamp biomicroscopy were also done. RESULTS Five patients had visual impairment, and 14 had temporal pallor of the optic disc. Fourteen presented visual field defects, the most frequent being concentric constriction and peripheral defects. Overall, 11 subjects had symptoms qualifying for the diagnosis of optic neuropathy. Two had spontaneous pendular nystagmus in primary position of gaze. Visual field defects and pallor of the optic discs were found in mild, moderate and severe forms of konzo. No correlation was found between the severity of the motor disability of konzo and the extent of visual field loss. CONCLUSIONS Konzo was associated with optic neuropathy and a few patients had nystagmus. Although the etiopathogenesis of this optic neuropathy remains to be elucidated, the symmetry of the involvement suggests a toxic origin. We suggest that cyanide causes the neuro-ophthalmological damage in konzo. However, the optic neuropathy in konzo patients does not resemble the features of the epidemic optic neuropathy in Tanzania, Cuba or Nigeria, Leber's hereditary optic neuropathy, tobacco amblyopia or vitamin B deficiency.
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Affiliation(s)
- J C K Mwanza
- Department of Ophthalmology, Kinshasa University Hospital, Kinshasa.
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