A case report of spontaneously healed isolated posterior inferior cerebellar artery dissection with headache alone

Background Isolated posterior inferior cerebellar artery dissections can cause subarachnoid hemorrhages or infarctions. Surgical treatments for hemorrhagic stroke cases and medical treatments using antithrombotic agents for ischemic stroke cases have been done, whereas there are very few reports on non-stroke posterior inferior cerebellar artery dissections and the treatment strategy for non-stroke cases has not been established. This is the first detailed report on spontaneously healed isolated posterior inferior cerebellar artery dissection with headache alone. Case presentation 48 years old healthy male felt severe right-side throbbing headache and came to OIKE Clinic on the fourth day after the onset. MRI studies revealed his right posterior inferior cerebellar artery dissection and showed no infarctions or hemorrhages. He was observed carefully under continuous monitoring of blood pressure and hydrated sufficiently, given analgesic anti-inflammatory agents. Two weeks later, the dissected vessel’s diameter grew up to the maximal size, though the patient’s headache was rapidly improved around that day. Surgical treatments for prevention of subarachnoid hemorrhage were considered but careful conservative therapy continued in accordance with the patient’s strong desire. Gradually the dissection finding had been improving. Four months later, MRI study showed his right posterior inferior cerebellar artery was seen almost normal in size and shape. Conclusions With the progress of high resolution MRI techniques, iPICAD will be detected more frequently. Further collection and assessment of iPICAD cases will lead to determine the optimal therapeutic strategy for iPICAD with headache alone.


Abstract
Background Isolated posterior inferior cerebellar artery dissections can cause subarachnoid hemorrhages or infarctions. Surgical treatments for hemorrhagic stroke cases and medical treatments using antithrombotic agents for ischemic stroke cases have been done, whereas there are very few reports on non-stroke posterior inferior cerebellar artery dissections and the treatment strategy for non-stroke cases has not been established. This is the first detailed report on spontaneously healed isolated posterior inferior cerebellar artery dissection with headache alone. Case presentation 48 years old healthy male felt severe right-side throbbing headache and came to OIKE Clinic on the fourth day after the onset. MRI studies revealed his right posterior inferior cerebellar artery dissection and showed no infarctions or hemorrhages. He was observed carefully under continuous monitoring of blood pressure and hydrated sufficiently, given analgesic anti-inflammatory agents. Two weeks later, the dissected vessel's diameter grew up to the maximal size, though the patient's headache was rapidly improved around that day.
Surgical treatments for prevention of subarachnoid hemorrhage were considered but careful conservative therapy continued in accordance with the patient's strong desire.
Gradually the dissection finding had been improving. Four months later, MRI study showed his right posterior inferior cerebellar artery was seen almost normal in size and shape.
Conclusions With the progress of high resolution MRI techniques, iPICAD will be detected more frequently. Further collection and assessment of iPICAD cases will lead to determine the optimal therapeutic strategy for iPICAD with headache alone.

Background
Isolated posterior inferior cerebellar artery dissections (iPICADs) can cause subarachnoid hemorrhages or infarctions1. The incidence of iPICAD had been thought very rare. The 3 reports of iPICAD with stroke, however, are increasing with the progress of high resolution MRI techniques. Surgical and endovascular treatments for hemorrhagic stroke cases and medical treatments using antiplatelet or anticoagulant agents for ischemic stroke cases have been done. The treatment strategy for iPICADs with headache alone, however, is not yet established, because the reports on non-stroke iPICADs are still rare. Herein, a nonstroke iPICAD case healed spontaneously is reported and the iPICAD cases in the literature are reviewed.
Case Presentation 48 years old male, who had no past medical or traumatic history and no family history of cerebral artery dissections, felt severe right-side throbbing headache suddenly and came to OIKE clinic on the fourth day after the onset. MRI study revealed a tiny dissection like finding (pearl and string sign like) on his right proximal segment (tonsillomedullar segment) of PICA (Fig.1A). Although no intramural hematoma, double lumen finding, or intimal flap were detected by MRI study, PICA dissection could not be denied and he was observed carefully under continuous monitoring of blood pressure, heart rate and other vital signs and he was hydrated sufficiently, given analgesic anti-inflammatory agents (a non-steroid anti-inflammatory drug: Loxoprofen Sodium Hydrate 60-300mg a day). The seventh day's MRI study showed that the diameter of the PICA was expanding more, and the patient was diagnosed with PICAD ( Fig.1B). The other MRI sequences showed no infarctions or hemorrhages (Fig 1C, D). Careful conservative therapy was continued. His headache severity was assessed by numerical rating scale (NRS) every day. The inner and outer diameters of the dissected PICA were measured by MRI T1-weighted high resolution vessel wall imaging (HRVWI) (Fig.1F) and T2-weighted HRVWI (basi-parallel anatomical scanning (BPAS)) ( Fig.2), respectively. Two weeks later after the onset of headache, the dissected vessel's diameter grew up to the maximal size ( Fig.2A), though the patient's 4 headache improved steeply on the eighth day ( Fig.3). At that point, surgical or endovascular treatments for prevention of subarachnoid hemorrhage were recommended but the patient desired to continue the conservative therapy, though he was explained the risk of his dissected PICA rupture. Since the eighth day, the patient did not feel severe headache again. Four weeks later after the onset, the dissection finding on MIP images began to improve. Eight weeks later after the onset, his PICA looked like almost normal on MIP and T1-weighted HRVWI and the outer diameter was still bulging on T2-weighted HRVWI (BPAS). Finally, four months later after the onset, the outer diameter was seen almost normal in size and shape (Fig.2). The patient runs marathon races again.

Discussion
MRI studies showed no apparent intramural hematoma, double lumen, or intimal flap indicating artery dissection. PICA is a tiny vessel and it would be possible that these findings could not be detected by MRI study. Recently, the chronological changes of the affected vessels' size and shape are considered as one criterion to diagnose cervicocephalic artery dissections including intracranial small vessels like PICA. Table 1. shows the Spontaneous Cervicocephalic Arterial Dissections Study (SCADS) criteria. According to the criteria, the patient was diagnosed with PICAD (criteria 5, 7, and 8 matched)2.
Conventional angiography was not performed for this patient. Conventional angiography could have given some useful information to decide this patient's therapeutic plan, but this patient refused any surgical or endovascular treatments and then conventional angiography was deliberately avoided to keep him in less invasive condition. Fortunately, the patient's PICAD healed without surgical or endovascular treatment and as a result, conventional angiography was not performed for this patient.
Of all cervicocephalic artery dissections, vertebral artery dissections (VADs) are common and the therapeutic strategy for VAD has been established3. The reports of iPICAD with stroke are increasing with the progress of high resolution MRI techniques but those with headache alone are still few. In the last decade, over 70 cases of iPICAD have been found in the literature, but almost all the cases were with subarachnoid hemorrhages4 or infarctions5. Non-stroke iPICAD cases were only two and one of two cases was diagnosed with the coexisting VAD6. PICA is a small vessel and PICAD is often tiny finding even with high resolution MRI techniques and therefore can be overlooked unless accompanied with stroke. The present case's patient was fortunately suspected to have iPICAD at the beginning of the clinical course and followed by MRI examination. High resolution vessel wall imaging (HRVWI) is informative. In this case, T1-weighted HRVWI was useful to confirm the intraluminal condition and size change. The outer diameter was followed by basiparallel anatomical scanning (BPAS), one type of T2-weighted HRVWI7. The outer diameter shrinkage followed the internal diameter improvement.
For VADs with headache alone, conservative therapies are usually selected. The therapeutic strategy for non-stroke iPICAD, however, is not yet determinate. The other case of the reported two iPICAD with headache alone was surgically treated to prevent subarachnoid hemorrhage because the dissection finding of radiological examination was progressive, though the patient headache had relieved8. In the cases that the dissection findings of radiological examination are progressive, it might be permissible to perform any surgical and/or endovascular treatments in order to avoid the rupture of dissected arteries.
But it should be noticeable that non-stroke iPICAD may heal spontaneously like the present 6 case. Maruyama et al. reported spontaneous vertebral and internal carotid artery dissection cases. They emphasized on the importance of the location, nature and severity of cervical and occipital pain9. In the present case, the patient felt severe throbbing headache continuously at least during his PICAD finding was worsening. After he relieved from the occipital pain, his PICAD finding stopped its exacerbation and gradually improved on MRI study. It is interesting that the severity of the patient's headache might be related to the PICAD condition.

Conclusions
This is the first detailed report on spontaneously occurred and healed iPICAD with headache alone, followed by MRI examinations. With the progress of high resolution MRI techniques, iPICAD will be detected more frequently. Further collection and assessment of iPICAD cases will lead to determine the optimal therapeutic strategy for iPICAD.     The patient' headache severity was measured by numerical rating scale (NRS) every day. The inner diameter of the affected PICA was measured using crosssectional view of T1-weighted HRVWI and the outer diameter was measured using original data of T2-weighted HRVWI (BPAS). Two weeks later after the onset of headache, the dissected vessel's diameter grew up to the maximal, though NRS score of the patient's headache improved steeply on the eighth day. Since then, NRS scores had been kept within 2. The maximum inner and outer diameters shrunk gradually to normal size.

Supplementary Files
This is a list of supplementary files associated with the primary manuscript. Click to download. CARE checklist.pdf Table 1 SCADS criteria.pdf