Someone was talking about an old autocratic prince that shot dead, saying:
You must understand that towards the end of his life he began to have those tricks of the nerves not uncommon with tyrants. He multiplied the ordinary daily and nightly guard round his castle till there seemed to be more sentry-boxes than houses in the town, and doubtful characters were shot without mercy.
Does it mean Neurological disorders?
Some definitions w/ examples:
nerves - The bodily state resulting from the influence of mental or physical stimuli, esp. with regard to a person's feeling or courage. Also, disordered or heightened sensitivity; anxiety, fearfulness, tension, etc.
He suffered an attack of nerves.
On the opening night at the Coliseum my nerves were wound tight like a clock.
trick - A mischievous act; A ludicrous or grotesque act done for fun and amusement.
Shorter Oxford English Dictionary
WordWeb
Note well, there are other definitions which may work here, but I don't feel they are as close or precise in meaning. E.g., "a special technique". Or, " A peculiar trait or characteristic".
Coalescing these, we may infer the meaning:
A mischievous and grotesque act of the nervous system rendering the subject highly anxious or fearful.
From The Consolidated Library (Vol. 2), Orison Swett Marden, editor-in-chief, 1907:
Some women put themselves into a thoroughly unwholesome condition during pregnancy by their fear of antenatal impressions. Many are the fearsome stories told in the twilight by old wives, and withheld ostentatiously from pregnant women. If antenatal impressions have any power over the unborn child — and this is by no means scientifically proved — it is through the nervous system of the mother. Her brooding is the only danger. The strongest nerves are not altogether controlled at such time, and therefore it behooves every woman to accustom herself to sane thoughts on this subject, and to sane and wholesome activities during the nine months. Work, and enough, though not too much of it; work, to the point of natural fatigue and sound sleep, though not to the point of nervous strain; this is the best antidote for all such tricks of the nerves. It keeps the mind to its proper function, and does not give it time to flee frantically from phantoms.
