discharges in sensorimotor cortex

Conducted rapidly in the pyramidal tracts

Focal or multifocal jerks

reticular firing causing more generalized axial jerks

Rostral & caudal spread of activity in reticulospinal pathways

focal & segmental

Little spread of activity from spinal generator sites

Longer and more variable duration jerks.

form of spinal myoclonus

Spinal generator recruits axial muscles via slowly conducting propriospinal pathways

more extensive jerks

typically, slow, rhythmic bilateral synchronous jerksof flexion muscles in trunk & lower limbs

Metabolic workup

FBE, UCE, Ca, Mg, PO4, LFT, TFT

NH3

MRI:

looking for pathology as precipitant

brain for cortical myoclonus, brainstem for reticular etc

Back average EEG:

eliminates cortical origin

Bereitschafts potential:

eliminates a cortical origin

EMG:

denervation at level of theoretical spinal injury

PolyEMG:

(Surface activation order EMG)

Establishes the chronological order and localises lesion in spine

C reflex:

reflection of hyperexcitability of the nervous system

Motor evoked potentials:

localises lesion

SSEP:

eliminates a cortical origin (look for giant cortical waves)