Subarachnoid hemorrhage diagnosis
For Aneurysmal subarachnoid hemorrhage diagnosis in the early phase, during the first 24 hours, cerebral CT, combined with intracranial CT angiography is recommended to make a positive diagnosis of SAH, to identify the cause and to investigate for an intracranial aneurysm.
Cranial magnetic resonance imaging may be proposed if the patient's clinical condition allows it. FLAIR imaging is more sensitive than CT to demonstrate a subarachnoid hemorrhage and offers greater degrees of sensitivity for the diagnosis of restricted subarachnoid hemorrhage in cortical sulcus. A lumbar puncture should be performed if these investigations are normal while clinical suspicion is high 1).
CT angiography is an appropriate initial investigation to detect macrovascular causes of non-traumatic Intracerebral hemorrhage, but accuracy is modest. Additional MRI/MRA may find cavernomas or alternative diagnoses, but DSA is needed to diagnose macrovascular causes undetected by CT angiography or MRI/MRA 2).
Head computed tomography for subarachnoid hemorrhage diagnosis
Cerebral magnetic resonance imaging for subarachnoid hemorrhage diagnosis
Lumbar Puncture
MRI of the spinal axis
The yield and clinical relevance of MRI of the spinal axis in patients who present with nonperimesencephalic subarachnoid hemorrhage (NPSAH) is low. Germans et al. do not recommend routine MRI of the spinal axis in this patient population, but it might be justified in a subgroup of patients 3).
The yield and clinical relevance of MRI of the spinal axis in patients who present with NPSAH is low. Germans et al. do not recommend routine MRI of the spinal axis in this patient population, but it might be justified in a subgroup of patients 4) 5).
Computed tomography angiography
Magnetic resonance angiography for intracranial aneurysm
Digital subtraction angiography
The knowledge from digital subtraction angiography (DSA) guides both definitive therapy and perioperative management based on the number, size and location of aneurysm and status of collateral circulation and vasospasm.
Hemogram, renal and hepatic function, electrolytes, coagulation status, electrocardiogram (ECG), echocardiogram and chest radiograph provides information about systemic effects of aSAH.
Certain patterns of SAH are associated with a low yield of abnormalities on repeat imaging if the initial angiography is normal. The pattern of hemorrhage on the presenting CT should be used to guide the most appropriate use of further imaging modalities and present a diagnostic algorithm for this purpose 6).
Transcranial Doppler (TCD) and ICP monitoring also help evaluation and management.
Screening
The low 1.14% per-person year risk of DNIA detection and small DNIA size at detection cannot justify routine screening for DNIAs in all patients with a personal history of IAs. If imaging follow-up is considered for selected patients, early screening will likely yield the most benefit in patients who continue to smoke cigarettes 7).
Since its introduction, digital subtraction angiography has been considered the gold standard in diagnostic imaging for neurovascular disease. Modern post-processing techniques have made angiography even more informative to the cerebrovascular neurosurgeon or neurointerventionalist.
In patients with a head computed tomography scan performed less than 6 h after headache onset and reported negative by a staff radiologist, lumbar puncture can be withheld. 8). Intracranial vascular lesions, such as a vascular loop, infundibulum, and stump of an occluded vessel, are sometimes misdiagnosed as aneurysms during imaging examinations 9).
It is difficult to differentiate such lesions from aneurysms on the basis of imaging findings 10) 11).