Can an intradural 1cm peripheral nerve sheath tumor on left side of thecal sac at l4 cause relative weakness in left leg, periodic aching in left leg, and increased coldness/ischemia in left foot?

Nerve compression: The symptoms you describe in the L4 nerve distribution are are certainly likely in the case of neoplasia-induced nerve root compression. Peripheral ischemia (arterial insufficiency) is less likely as a direct result of the mass you describe.

Yes, it could: Your symptoms are suggestive of a likely relation between the leg weakness and the tumor in the spinal canal. You should be examined by a neurologist or neurosurgeon to help you further by considerations like removal to diagnose the nature of this tumor and further treatment intervention.

Neuro problems: A nerve sheath tumor can cause pain, weakness, tingling and numbness, usually not ischemia.