Table 1.
Studies showing short-latency afferent inhibition (SAI) alteration in Parkinson’s Disease (PD) patients.
| Reference | Participants (mean age ± SD, y) | ON/OFF medication (UPDRS III) | Disease duration (years) or (months)° | L-dopa equivalent dose (mg) | Cognitive decline | SAI | Main findings | Interpretation |
|---|---|---|---|---|---|---|---|---|
| ISI | ||||||||
| Versace et al. (2017) | 15 PD borderline OERP (69.9 ± 5.4) 13 PD absent OERP (71.8 ± 5.4) 30 HC (67.4 ± 4.8) | PD-ON borderline OERP (16.1 ± 5.4) PD-ON absent OERP (16.9 ± 5.1) | PD-ON borderline OERP (7.7 ± 4.7) PD-ON absent OERP (8.0 ± 4.7) | PD-ON borderline OERP (516.7 ± 209.3) PD-ON absent OERP (530.8 ± 184.3) | MCI Level I in PD with absent OERP (92%) and in PD with borderline OERP (20%)* | N20+2 to +8 ms (1 ms Δ) | ↓ SAI in PD with absent OERP | Altered SAI in PD patients with olfactory dysfunction and cognitive impairment |
| Oh et al. (2017) | 28 PD hyposmia (63.04 ± 1.73) 26 PD anosmia (70.5 ± 1.88) 17 PD normosmia (67.35 ± 2.22) 20 HC (68.45 ± 1.61) | PD-ON hyposmia (18.96 ± 1.31) PD-ON anosmia (21.67 ± 2.27) PD-ON normosmia (14.94 ± 2.3) | PD-ON hyposmia (18.43 ± 1.56)° PD-ON anosmia (21.62 ± 1.68)° PD-ON normosmia (15.24 ± 1.78)° | PD-ON hyposmia (558.83 ± 47.02) PD-ON anosmia (544.7 ± 43.98) PD-ON normosmia (371.18 ± 43.8) | Normal MMSE | N20 to +4 ms (2 ms Δ) | ↓ SAI in PD hyposmia and anosmia | Altered SAI in PD patients with olfactory dysfunction |
| Pelosin et al. (2016) | 33 PD-fallers (7.6 ± 4.4) 17 elderly men-fallers (73.4 ± 4.2) 10 elderly men non-fallers (72.1 ± 4.9) | PD-ON (30.3 ± 9.13) | NA | 775.5 ± 358.6 | MCI Level I in PD-fallers* | N20-2 to +8 ms (2 ms Δ) | ↓ SAI in PD-fallers and elderly men fallers | Altered cholinergic activity in patients with gait disturbances |
| Lee et al. (2015) | 12 PD with dysphagia (73.33 ± 6.48) 17 PD without dysphagia (71.06 ± 6.98) 11 HC (62.4 ± 6.2) | PD-ON with dysphagia (24.17 ± 6.53) PD-ON without dysphagia (20.06 ± 4.07) | PD-ON with dysphagia (17.92 ± 9.16)° PD-ON without dysphagia (11.94 ± 4.98)° | PD-ON with dysphagia (589.58 ± 254.50) PD-ON without dysphagia (488.82 ± 181.86) | Normal MMSE | N20 to +4 ms (1 ms Δ) | ↓ SAI in PD with dysphagia | Altered cholinergic activity in patients with dysphagia |
| Wagle Shukla et al. (2013) | 11 PD with STN-DBS (58 ± 8.3) 10 HC (56 ± 7.1) | 12 CONDITIONS | 13.18 ± 4.21 | 1576.09 ± 1076.22 | NA | N20 | SAI is normalized 6 months after STN-DBS implant | Long-term STN-DBS improves sensorimotor integration and proprioception |
| Brusa et al. (2014) | 10 PSP (59.3 ± 6.6) 10 PD (58 ± 6.4) 10 HC (57.2 ± 6.2) | PSP-ON (62.6 ± 9.4) PD-ON (36.2 ± 9) | PSP-ON (7 ± 1.2) PD-ON (6.3 ± 1.5) | PSP-ON (500 ± 150) PD-ON (750 ± 125) | Normal MMSE | N20-4 to +8 ms (4 ms Δ) | ↓ SAI in PSP compared to PD, no effect induced by cerebellar iTBS | Cerebellar iTBS modulates cerebellar-cortical connectivity without affecting sensorimotor integration in PSP |
| Celebi et al. (2014) | 11 MSA-P (58.7 ± 2.6) 8 MSA-C (58.9 ± 2.1) 10 PD (61.8 ± 1.8) 10 HC (65.8 ± 2.1) | PD-ON (8.8 ± 1.6) | 3.2 ± 0.6 | 545 ± 57.6 | MCI Level I in MSA type C and P* | N20+1 to +4 ms (1 ms Δ) | ↓ SAI in MSA-C compared to PD and correlates with neuropsychological scores | Cholinergic dysfunction in MSA-C patients and cognitive impairment |
| Yarnall et al. (2013) | 11 PD with MCI (73.3) 11 PD without MCI (66.9) 22 HC (67.9) | PD-ON with MCI (28.5) PD-ON without MCI (28.7) | PD-ON with MCI (20)° PD-ON without MCI (28.5)° | PD-ON with MCI (343.5) PD-ON without MCI (288.1) | MCI Level I in PD* | N20 | ↓ SAI in PD with MCI and correlates with MoCA score | Cholinergic dysfunction occurs early in PD with MCI |
| Nardone et al. (2013) | 10 PD with RBD (65.9 ± 6.5) 13 PD without RBD (63.7 ± 6.4) 15 HC (66.4 ± 7) | PD-ON with RBD (17.5 ± 4.3) PD-ON without RBD (18.3 ± 4.3) | PD-ON with RBD (5 ± 2.3) PD-ON without RBD (6 ± 0.8) | PD-ON with RBD (578 ± 2.9) PD-ON without RBD (627 ± 341) | MCI in PD with RBD (90%) and without RBD (38%)# | N20+2 to +8 ms (1 ms Δ) | ↓ SAI in PD with RBD and correlates with neuropsychological scores | Cholinergic dysfunction in PD with RBD and cognitive impairment |
| Rochester et al. (2012) | 22 PD (70.18 ± 9.67) 22 HC (67.43 ± 8.43) | PD-ON (29.14 ± 9.54) | 19.83 ± 8.6° | 304.86 ± 130.91 | MCI Level I in PD* | N20 to +4 ms (1 ms Δ) | ↓ SAI in PD | Altered cholinergic activity in PD correlates with gait dysfunction |
| Celebi et al. (2012) | 10 PD (72 ± 1.4) 10 PD with dementia (75 ± 2.2) 10 AD (76 ± 1.7) 10 HC (72.1 ± 2.3) | PD-ON (9.8 ± 1.6) PD-ON with dementia (22.9 ± 1.7) | PD-ON (2.3 ± 0.5) PD-ON with dementia (8.4 ± 1.6) | PD-ON (345.5 ± 77.7) PD-ON with dementia (943 ± 147.2) | Mild-moderate dementia | N20+1 to +8 ms (1 ms Δ) | ↓ SAI in PD with dementia and AD | Cholinergic dysfunction in PD with dementia |
| Manganelli et al. (2009) | 10 PD with VH (70.4 ± 5.3) 12 PD without VH (65.5 ± 10.1) 11 HC (62.4 ± 6.2) | PD-ON with VH (70.4 ± 5.3) PD-ON without VH (65.5 ± 10.1) | PD-ON with visual hallucination (8.7 ± 6.3) PD-ON without visual hallucination (9 ± 5.5) | PD-ON with visual hallucination (535.9 ± 307.8) PD-ON without visual hallucination (697.9 ± 271.5) | MCI in PD with VH (90%) and without VH (58%)§ | N20+2 to +8 ms (2 ms Δ) | ↓ SAI in PD with VH | Cholinergic dysfunction in PD patients with visual hallucinations and cognitive impairment |
| Sailer et al. (2007) | 7 PD with STN-DBS (56.1 ± 3.6) 7 HC (56 ± 6.3) | PD-ON-STIM-OFF (10.86 ± 3.44) PD-ON-STIM-ON (7 ± 2.38) PD-OFF-STIM-OFF (6.17 ± 2.14) PD-OFF-STIM-ON (5.17 ± 2.23) | 14 ± 4.51 | 723.14 ± 412.62 | NA | N20+3 | ↓ SAI in PD-ON stimulator-OFF, SAI is restored by stimulator-ON | STN-DBS improves acutely sensorimotor integration |
| Sailer et al. (2003) | 10 PD (58.2 ± 9.8) 10 HC (59.5 ± 10.7) | PD-ON (12.8 ± 6.3) PD-OFF (23.7 ± 11.1) | 7.4 ± 5.7 | 835.25 ± 614.08 | NA | N20 (MN) N23 (D3) | ↓ SAI in PD-ON more affected side and normal in PD-OFF | SAI is altered by dopaminergic medication and may contribute to the side effects of dopaminergic drugs |
MN, median nerve stimulation; D3, digit 3 stimulation; iTBS, intermittent theta-burst-stimulation; NA, not applicable; PD, Parkinson’s Disease; HC, healthy control; VH, visual hallucination; RBD, REM-sleep Behavior Disorders; MSA-P, multiple system atrophy parkinsonian type; MSA-C, multiple system atrophy cerebellar type; PSP, progressive supranuclear palsy; AD, Alzheimer disease; OERP, Olfactory Event-Related Potentials; STN-DBS, subthalamic nucleus deep brain stimulation; MMSE, mini mental state examination; MoCA, Montreal Cognitive Assessment; MCI, mild cognitive impairment; *MCI criteria according to the Level I of the MDS (Movement Disorder Society) commissioned Task Force (Litvan et al., 2012); #MCI criteria according to Petersen and Morris, 2005; §MCI criteria according to Caviness et al., 2007.