Browsing by Author "Krishnan, S"

Now showing 1 - 16 of 16
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    Acquired hepatolenticular degeneration: Is the T1 hyperintensity due to manganese deposition?
    (NEUROLOGY INDIA, 2009) Baheti, NN; Hassan, H; Rathore, C; Krishnan, S; Kesavadas, C
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    Cerebellar Sensory Processing Alterations Impact Motor Cortical Plasticity in Parkinson's Disease: Clues from Dyskinetic Patients
    (Cereb. Cortex (2013), 2013-04) Kishore, A; Popa, T; Balachandran, A; Chandran, S; Pradeep, S; Backer, F; Krishnan, S; Meunier, S
    The plasticity of primary motor cortex (M1) in patients with Parkinson's disease (PD) and levodopa-induced dyskinesias (LIDs) is severely impaired. We recently reported in young healthy subjects that inhibitory cerebellar stimulation enhanced the sensorimotor plasticity of M1 that was induced by paired associative stimulation (PAS). This study demonstrates that the deficient sensorimotor M1 plasticity in 16 patients with LIDs could be reinstated by a single session of real inhibitory cerebellar stimulation but not sham stimulation. This was evident only when a sensory component was involved in the induction of plasticity, indicating that cerebellar sensory processing function is involved in the resurgence of M1 plasticity. The benefit of inhibitory cerebellar stimulation on LIDs is known. To explore whether this benefit is linked to the restoration of sensorimotor plasticity of M1, we conducted an additional study looking at changes in LIDs and PAS-induced plasticity after 10 sessions of either bilateral, real inhibitory cerebellar stimulation or sham stimulation. Only real and not sham stimulation had an antidyskinetic effect and it was paralleled by a resurgence in the sensorimotor plasticity of M1. These results suggest that alterations in cerebellar sensory processing function, occurring secondary to abnormal basal ganglia signals reaching it, may be an important element contributing to the maladaptive sensorimotor plasticity of M1 and the emergence of abnormal involuntary movements.
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    Dopamine D3 receptor Ser9Gly variant is associated with impulse control disorders in Parkinson's disease patients
    (Parkinsonism Relat Disord., 2016-12) Krishnamoorthy, S; Rajan, R; Banerjee, M; Kumar, H; Sarma, G; Krishnan, S; Sarma, S; Kishore, A
    Introduction: Impulse control disorders (ICD) are reported to occur at variable frequencies in different ethnic groups. Genetic vulnerability is suspected to underlie the individual risk for ICD. We investigated whether the allelic variants of dopamine (DRD3), glutamate (GRIN2B) and serotonin (HTR2A) receptors are linked to ICD in Indian Parkinson’s disease (PD) patients. Methods: We conducted a prospective, case-control study which included PD patients (70 with ICD, 100 without ICD categorized after direct psychiatric interview of patient and caregiver) and 285 healthy controls. Single nucleotide polymorphism (SNP) variants of DRD3 p.S9G (rs6280), GRIN2B c.2664C>T (rs1806201) and HTR2A c.102T>C (rs6313) were genotyped. Results: Multivariate regression analysis revealed that DRD3 p.Ser9Gly (rs6280) heterozygous variant CT (OR ¼ 2.22, 95% CI: 1.03e4.86, p ¼ 0.041), higher daily Levodopa equivalent doses (LED) of drugs (for 100 mg LED, OR ¼ 1.14, 95% CI: 1.01e1.29, p ¼ 0.041), current dopamine agonist but not Levodopa use (OR ¼ 2.16, 95% CI: 1.03e4.55, p ¼ 0.042) and age of onset of motor symptoms under 50 years (OR 2.09, 95% CI: 1.05e4.18, p ¼ 0.035) were independently associated with ICD. Conclusion: DRD3 p.Ser9Gly (rs6280) CT genotype is associated with ICD in Indian PD patients and this association is novel. Enhanced D3 receptor affinity due to gain-of-function conferred by the glycine residues could impair reward-risk assessment in the mesolimbic system and contribute to development of impulsive behaviour, in carriers of this genotype.
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    Evaluating Birth Preparedness and Pregnancy Complications Readiness Knowledge and Skills of Accredited Social Health Activists in India
    (Int. J of MCH and AIDS. 2013, 2013-09) Kochukuttan, S; Ravindran, TKS; Krishnan, S
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    Gender influence on selection and outcome of deep brain stimulation for Parkinsons disease
    (ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2014) Chandran, S; Krishnan, S; Rao, RM; Sarma, SG; Sarma, PS; Kishore, A
    Background: Gender differences exist in Parkinsons disease (PD), both in clinical manifestations and response to medical treatment. We investigated whether gender differences occur in the clinical characteristics of patients selected for bilateral subthalamic nucleus deep brain stimulation (STN DBS) or in the outcome when resource limits influence treatment choices made by patients. Materials and Methods: Fifty-one consecutive patients were evaluated 1 month before, and 12 months after bilateral STN DBS. All patients were rated using Unified Parkinsons Disease Rating Scale, Parkinsons Disease Quality of Life (PDQL) Scale, Addenbrookes Cognitive Examination and Beck Depression Inventory. Results: Pre-operative characteristics did not differ between the genders except for lower doses of drugs (P = 0.03), worse emotional scores in PDQL (P = 0.01) and worse depression (P = 0.03) in women. There was no gender difference in the surgical outcome, except a lesser reduction of dopaminergic drugs in women. Depression and quality of life (QOL) improved equally well in women and men. Conclusion: Bilateral STN DBS is equally efficacious in both genders as a treatment for motor complications of PD and for improving QOL. Women are likely to be undertreated because of more severe dyskinesia and may experience less emotional well-being, and could therefore potentially benefit from earlier surgical treatment.
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    Guillain-Barre Syndrome with Acute Lymphoblastic Leukemia
    (INDIAN PEDIATRICS, 2013) Rajeswari, B; Krishnan, S; Sarada, C; Kusumakumary, P
    Guillain-Barre syndrome (GBS) is rarely reported in children with acute lymphoblastic leukemia and may be difficult to differentiate from vincristine induced neuropathy. We report two children with acute lymphoblastic leukemia on induction chemotherapy who developed GBS. The diagnostic issues and potential pathogenic mechanisms underlying GBS in pediatric patients with ALL are discussed.
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    Impulse Control Disorders and Related Behaviors in Indian Patients With Parkinson's Disease
    (MOVEMENT DISORDERS, 2013) Sarathchandran, P; Soman, S; Sarma, G; Krishnan, S; Kishore, A
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    Intracerebral hemorrhages in Vogt-Koyanagi-Harada disease
    (NEUROLOGY INDIA, 2009) Baheti, NN; Cherian, A; Kate, M; Krishnan, S; Thomas, B
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    Malignant Subthalamic Nucleus-Deep Brain Stimulation Withdrawal Syndrome in Parkinson's Disease
    (Mov Disord Clin Pract, 2016-03) Rajan, R; Krishnan, S; Kesavapisharady, KK; Kishore, A
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    Motor cortex plasticity can indicate vulnerability to motor fluctuation and high L-DOPA need in drug-naïve Parkinson's disease.
    (Parkinsonism Relat Disord., 2016-12) Kishore, A; James, P; Krishnan, S; Yahia-Cherif, L; Meunier, S; Popa, T
    Introduction: Motor cortex plasticity is reported to be decreased in Parkinson's disease in studies which pooled patients in various stages of the disease. Whether the early decrease in plasticity is related to the motor signs or is linked to the future development of motor complications of treatment is unclear. The aim of the study was to test if motor cortex plasticity and its cerebellar modulation are impaired in treatment-naïve Parkinson's disease, are related to the motor signs of the disease and predict occurrence of motor complications of treatment. Methods: Twenty-nine denovo patients with Parkinson's disease were longitudinally assessed for motor complications for four years. Using transcranial magnetic stimulation, the plasticity of the motor cortex and its cerebellar modulation were measured (response to paired-associative stimulation alone or preceded by 2 active cerebellar stimulation protocols), both in the untreated state and after a single dose of L-DOPA. Twenty-six matched, healthy volunteers were tested, only without L-DOPA. Results: Patients and healthy controls had similar proportions of responders and non-responders to plasticity induction. In the untreated state, the more efficient was the cerebellar modulation of motor cortex plasticity, the lower were the bradykinesia and rigidity scores. The extent of the individual plastic response to paired associative stimulation could indicate a vulnerability to develop early motor fluctuation but not dyskinesia. Conclusions: Measuring motor cortex plasticity in denovo Parkinson's disease could be a neurophysiological parameter that may help identify patients with greater propensity for early motor fluctuations.
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    Parkinson's disease
    (Ann Indian Acad Neurol, 2011-07) Behari, M; Bhattacharyya, KB; Borgohain, R; Das, SK; Ghosh, B; Kishore, A; Krishnan, S; Mridula, KR; Muthane, U; Pal, PK; Sankhla, C; Shukla, G
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    Parkinson's disease
    (ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2011) Behari, M; Bhattacharyya, KB; Borgohain, R; Das, SK; Ghosh, B; Kishore, A; Krishnan, S; Mridula, KR; Muthane, U; Pal, PK; Sankhla, C; Shukla, G
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    Severity of Writer's Cramp is Related to Faulty Motor Preparation
    (Cereb Cortex, 2017-09) Kishore, A; Popa, T; James, P; Krishnan, S; Robert, S; Meunier, S
    We characterized, in 37 writer's cramp (WC) patients and 14 healthy volunteers (HV), the buildup of motor representations contralateral ("intended") and ispsilateral ("unintended") to the movement to be produced and the excitability changes in left primary motor cortex during the early reaction time (RT) of a pre-cued reaching movement to pick up a pen with either hand to write. We also tested the excitability of interhemispheric pathways from right dorsal premotor and motor cortices to left motor cortex. During early RT (1) the motor cortex excitability of unintended muscle representations did not decrease in patients as in HV and (2) the connection from the contralateral dorsal premotor cortex to the "intended" motor representation did not function in patients. In HV, the efficiency of intracortical GABA-ergic circuits at rest predicted the degree of excitability changes in the intended motor representation in the early RT. This was not true in patients who had lower efficiency of GABA-ergic circuits. Interestingly, the more severe was the writing impairment, the higher was the level of excitability in the intended and unintended motor representations. It demonstrates, for the first time, that abnormal motor preparation influences the severity of the writing impairment in WC patients.
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    Surgical Treatment of Levodopa-induced Dyskinesia in Parkinson's Disease
    (Ann Indian Acad Neurol., 2017-09) Krishnan, S; Pisharady, KK
    The treatment of motor manifestations of Parkinson's disease (PD) is essentially a trade-off between adequate relief of motor symptoms and prevention and control of motor complications, particularly levodopa-induced dyskinesia (LID). Progression of PD is paralleled by a progressive difficulty in achieving the balance. Functional neurosurgical procedures provide sustained relief of LID in carefully selected patients when further tailoring of medical therapy fails to achieve this goal. Though deep brain stimulation (DBS) has superseded lesioning surgeries, pallidotomy still has a role in those patients in whom DBS is not feasible for financial or other reasons.
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    The decade after subthalamic stimulation in advanced Parkinson's disease: A balancing act
    (NEUROLOGY INDIA, 2016) Krishnan, S; Prasad, S; Pisharady, KK; Sarma, G; Sarma, SP; Kishore, A
    Aim: The duration of improvement in quality of life after subthalamic nucleus deep brain stimulation (STN DBS) for Parkinson's disease (PD) and the presurgical identification of factors predicting sustained clinical benefits have implications in patient selection and timing of surgery. These aspects were assessed in patients who underwent yearly assessment for at least 7 years after surgery. Materials and Methods: The quality of life, motor and cognitive outcomes of 25 patients who completed the 7-year assessment, and 12 patients who completed the 10-year assessment, were analyzed. Results: The improvement in quality of life was sustained only for 5 years, while the severity of motor signs and motor fluctuations remained reduced at 7 and 10 years. Tremor and rigidity showed more enduring reduction than bradykinesia and axial signs. The dose reduction in medications could be maintained until 7 years, by which time, the axial scores were worse than that seen at the pre-DBS levels. At 10 years, a higher levodopa requirement and recurrence of dyskinesias were noted. Patients with greater pre-DBS levodopa-responsive motor signs had greater long-term motor improvement. Conclusions: STN DBS performed in patients with advanced motor fluctuations and severe dyskinesias provide only an average of 5 years of quality of life improvement. STN DBS in patients with motor signs that are less responsive to levodopa results in shorter duration of clinical benefits. The improvements in the severity of motor fluctuations, rigidity, and tremor are the most enduring benefits of STN DBS that last a decade. However, these are offset by worsening axial and cognitive functions, bradykinesia, a higher levodopa requirement, and recurrence of dyskinesias by the end of the decade.
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    Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson's disease
    (NEUROLOGY INDIA, 2015) Krishnan, S; Justus, S; Meluveettil, R; Menon, RN; Sarma, SP; Kishore, A
    Background: The Montreal Cognitive Assessment is a brief and easy screening tool for accurately testing cognitive dysfunction in Parkinson's disease. We tested its validity for use in non-English (Malayalam) speaking patients with Parkinson's disease. Materials and Methods: We developed a Malayalam (a south-Indian language) version of Montreal Cognitive Assessment and applied to 70 patients with Parkinson's disease and 60 age-and education-matched healthy controls. Metric properties were assessed, and the scores were compared with the performance in validated Malayalam versions of Mini Mental Status Examination and Addenbrooke's Cognitive Examination. Results: The Montreal Cognitive Assessment-Malayalam showed good internal consistency and test-retest reliability and its scores correlated with Mini Mental Status Examination (patients: R = 0.70; P < 0.001; healthy controls: R = 0.26; P = 0.04) and Addenbrooke's Cognitive Examination (patients: R = 0.8; P < 0.001; healthy controls: R = 0.52; P < 0.001) scores. Conclusion: This study establishes the reliability of cross-cultural adaptation of Montreal Cognitive Assessment for assessing cognition in Malayalam-speaking Parkinson's disease patients for early screening and potential future interventions for cognitive dysfunction.