1) By fits and starts 2) Jerkily 1) In spurts and fits 2) Jerkily 3) With spasms 
[adv] - with spasms 2. [adv] - in spurts and fits
spasmodically 1. With spasms: 'Her mouth was slightly open, and jerked violently and spasmodically at one corner.' 2. In spurts and fits: 'His wife began to write intermittently and spasmodically.' 3. Resembling a spasm or spasms; sudden but brief; sporadic. 3. Given to or characterized by bursts of excitement.
adverb in spurts and fits; `I began to write intermittently and spasmodically`