Botulinum toxin type-A treatment in spastic paraparesis: a neurophysiological study.
OBJECTIVE
The aim of this study was to verify the action of Botulinum toxin type-A (BoNT-A) by means of neurophysiological techniques, in patients presenting lower limb spasticity and requiring BoNT-A injections in the calf muscles, due to the poor response to medical antispastic treatment.


METHODS
Patients presenting paraparesis were enrolled. They underwent clinical evaluation for spasticity according to the Ashworth scale and neurophysiological recordings including: motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) of the leg area; compound motor action potential (cMAP) to tibial nerve stimulation, F-wave, and H-reflex before the treatment and 24 h, 2 weeks and 1 month after the injection of BoNT-A. In all patients, gastrocnemius was treated and in some cases soleus or tibialis posterior muscles were also injected.


RESULTS
In all patients, BoNT-A injections induced a clear clinical improvement as showed by the reduced spasticity values of the Ashworth scale. A significant increment of MEP latency and central conduction time (CCT) duration were observed 2 weeks after the treatment only in the injected muscles.


CONCLUSIONS
Prolonged MEP latencies and CCT after BoNT-A injections is probably due to a central alteration in responsiveness of spinal motor neurons to descending impulses from the corticospinal tracts. Such changes represent objective parameters heralding clinical efficacy of treatment.
Pauri
F
F
AFaR-CRCCS Centro di Ricovero e Cura a Carattere Scientifico: Divisione di Neurologia, Ospedale Fatebenefratelli, Isola Tiberina 39, 00186, Roma, Italy.
Boffa
L
L
Cassetta
E
E
Pasqualetti
P
P
Rossini
P M
PM
D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000009:adverse effects; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006181:H-Reflex / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D020336:Paraparesis, Spastic / Q000188:drug therapy* / Q000503:physiopathology; D010525:Peripheral Nerves / Q000187:drug effects / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000187:drug effects / Q000503:physiopathology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects / Q000503:physiopathology
D019274:Botulinum Toxins, Type A