Young black male with 4 month history of severe headache. HA is positional and improved with laying down and also worse with certain head postitions. His headache was preceded by a few days of neck pain and there was no history of trauma.

Head CT and Brain MR showed tentorial, right convexity and posterior left interhemispheric subdural hygromas. Tonsils not low and no sagging of the base of the brain.

Whole spine MR did not show defnitive epidural CSF to localize leak but did show probable lumbar subdural hygroma distorting the cauda equina. A disc protrusion at C5/6 was noted without high grade stenosis.

OP with LP at L5S1 below spinal SD hygroma was 150mm with closing pressure 80mm. CSF was normal. Myelogram with decubitus positioning did not show definitive leak. Post myelogram CT showed locallized dorsal epidural contrast distorting the dura between C6 and T8 similar to dorsal epidural arachnoid cyst.  No free epidural contrast extending into foramen etc.  Also extensive subdural hygroma in the lower thoracic and upper lumbar spine with slightly different density opacified CSF. Upper cervical subdural hygroma contiguous with posterior fossa subdural hygroma also noted.

14 cc epidural blood patch at T2/3 by experienced anesthesiologist after tap was not wet and normal epiduragram, probably injected dorsal to the epidural collection. Only transient improvement for less than 24 hours and now severe recurrent symptoms. The pain doc is asking me what to do next.

Does he have SIH? Ever seen or heard of spinal subdural hygroma in SIH?

Should I measure OP at C1C2 to verify diagnosis or does he clearly have it and the normal lumbar opening pressure related to the subdural hygroma?

Should I suggest a CT guided thoracid blood patch with injection into the dorsal lower cervical/upper thoracic epidural collection or might there be a wide communication with the subarachnoid space? Is this a thoracic epidural arachnoid cyst and not leakage of CSF that is seen in SIH?

Would another myelogram after cervical puncture potentially add anything?

The more I think about this case, the less confident I am that he has SIH but it is hard to believe that his positional HA is not related to the findings in the spine.

This is an active case and would be interested in any thoughts.