A 55-year-old woman presented with acute onset of severe headache, and possible witnessed seizure. Imaging confirmed intraventricular hemorrhage primarily focused within the fourth ventricle with diffuse subarachnoid hemorrhage within the posterior fossa and along the tentorium (Fig. 1 A). No severe neurologic deficits were observed initially. Her cerebral angiogram revealed a high flow dural arterial venous fistulous malformation of the tentorium supplied by the bilateral external carotid and left vertebral arteries into a large venous varix within the fourth ventricle at the site of the hemorrhage (Fig. 1 B, C). Deep venous drainage is observed into the Galenic and Straight Sinus of the posterior fossa. Successful trans-arterial embolization with liquid embolics (N-butyl cyanoacrylate, NBCA) of the bilateral external and left vertebral posterior meningeal artery feeders was successful at reducing >90% of these high-pressure indirect shunts (Fig. 1 D), with a small residual shunts from the distal occipital arteries that were subsequently targeted for cure with Gamma Knife Radiosurgery.
Figure 1. [A] Ruptured aneurysm of the Deep Venous Posterior Fossa drainage and AV shunting [B] Posterior Meningeal Artery Fistula [C] Right Middle Meningeal Artery Fistula [D] Post embolization Left Vertebral Angiogram demonstrates resolution of the high flow and pressure A-V Shunting following successful embolization with liquid embolics (NBCA).
Key Learning Points:

  1. Indirect Dural AV Fistula Vascular Malformations represent high risk lesions that result from acquired and/or congenital indirect fistula and A-V shunts that can arise within many of the deep venous structures of the brain (Superficial and Deep Venous Drainage systems). 
  2. Many patients may present with initially mild symptoms of pulsatile tinnitus or headaches but may progress over time to more severe high-risk symptomatology including hemorrhagic stroke, permanent neurologic deficits, and even mortality. 
  3. Early evaluation by an expert multi-disciplinary team is critical to diagnosis, management, and successful treatment and recovery with a variety of medical, endovascular, and surgical approaches.
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Central Retinal Artery Occlusion -
IA tPA and Hyperbaric Oxygen Therapy
Our patient is a 70-year-old man with a PMH of anxiety, depression, GERD, and mitral valve repair. He was in usual state of health on the night prior going to bed at 3 am. The next morning he awoke at 9 am with left eye vision loss except for a small crescent of vision in his central vision. He denied eye pain, headache, trauma. He denied temporal artery tenderness, headaches, or jaw claudication. No prior history of glaucoma. Emergent ophthalmologic and stroke neurology consultation confirmed a diagnosis of left Central Retinal Artery Occlusion (CRAO) with macular sparing (Fig 1A-Fundoscopic OS Pre-tPA). Emergent consultation for interventional therapy was requested. 

NEURO-INTERVENTIONAL THERAPY AND HYPERBARIC OXYGEN THERAPY
Dr. Sundeep Mangla performed emergent angiography of the left internal carotid artery and left ophthalmic artery, demonstrating normal origin of the ophthalmic artery with a poor choroidal blush confirming the diagnosis of retinal ischemia (Figure 2, A+B). Superselective angiography of the ophthalmic artery was performed followed by intra-arterial infusion of tPA at a concentration of 0.4 mg/cc for a total dose of 4 mg over 5-7 minutes. The patient reported significantly improved vision immediately after IA tPA therapy, with persistent lateral field cut. The patient then received post interventional hyperbaric oxygen therapy (2.0 – 2.6 atmospheres, 90-120 mins duration) for 4 sessions starting within 12 hours of diagnosis and treatment. A follow-up fundoscopic examination demonstrates improved perfusion of the retinal branches (Figure 1A and 1B, immediate and 2 days post fundoscopic). MRI of the brain confirmed an embolic source of the CRAO, with additional small diffusion positive strokes within the left hemisphere. He was discharged home with significantly improved vision in the left eye for continued outpatient therapy and management.
Figure 1A: OS A. CRAO pre tPA
Figure 1B: OS B. 30 mins post IA tPA demonstrates improved perfusion and branching vessels of retina
SUMMARY AND DISCUSSION
Central Retinal Artery Occlusion (CRAO) represents on neuro-ophthalmologic emergency, which can lead to irreversible retinal damage secondary to ischemia of a terminal vessel (without collaterals). It is characterized by a sudden, unilateral and painless loss of vision. Embolism is the most common cause of CRAO, the major source of which is carotid artery disease. The natural history for spontaneous recovery or improvement with conservative measures (including paracentesis, acetazolamide, anticoagulation and/or antiplatelets) remains poor, ranging from 20-30% for some measures of functional visional improvement. In studies comparing selective thrombolysis with conservative therapy, Schmidt et al. reported 58% of the interventional therapy group compared with 29% of the control group demonstrated partial improvement in visual acuity, with 77% vs. 26% if treated within 6 hours. 1 Additional studies delivering lower doses of tPA within 4 hours of onset published by Aldrich and colleagues demonstrated significant improvement in visual acuity (at least 1 line on the Snellen chart) in 76% of patients receiving intra-arterial therapy versus 33% of patients in the control group. The Interventional group was 13 times more likely to have improvement in visual acuity of 3 lines or more and 4.9 times more likely to have a visual acuity of 20/200 or better. 2 Although limited due to the heterogeneity of the presentations and therapeutic regimens applied, early experiences suggest opportunities for improved outcomes.
Figure 2. A. Left ICA Angiogram CRaO; B. Selective infusion 4 mg tPA; C. Post IA tPA
(OA-Ophthalmic Artery, CRA-Central Retinal Artery, CB-Choroidal Blush, PCA-Posterior Ciliary Artery)
Hyperbaric oxygen therapy (HBOT) has been associated with visual improvement in retrospective studies. 3 HBOT can maintain oxygenation of the retina through the choroidal blood supply, decrease edema and preserve compromised tissue adjacent to ischemic area. Important key factors for improvement include early therapy (<4-12 hours), degree of vessel occlusion, type of vessel occluded and presence of an adequate PaO2 of oxygen. 4

Our patient experienced the most severe form of CRAO with complete vision loss with only light perception. Despite this critical presentation, with a combination of early Neurointerventional therapy with intra-arterial thrombolysis directed to provide primary revascularization and Hyperbaric oxygen therapy to improve collateral and retinal perfusion, he was able to achieve early functional visual improvement of movement, objects, and color in his lateral fields. CRAO represents an ocular emergency with devastating outcomes. Poor outcomes are more commonly observed with delayed presentation, complete vision loss, and conservative management. Early recognition and potential multi-disciplinary treatment plans may offer patients an opportunity for improved functional outcomes and restoration of vision for these ophthalmologic emergencies and impending strokes of the eyes.
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Y Neuroendovascular Case Study:
A painful, enlarging mass behind ear of young girl.
The patient is an eleven year old girl who presented with a painful, discolored swelling behind her left ear. She said the swelling had increased noticeably in size over the previous 6 months.

The swollen area, upon physical examination, proved to be a pulsatile mass, with some reddish discoloration. (Fig. 1A) The results of MRI/MRA imaging was consistent with an extra-cranial AVM, with feeders from the anterior and posterior auricular branches. There was suggestion of feeders from branches of the middle meningeal artery.

Selective angiogram confirmed feeders from the anterior and posterior auricular arteries. (Fig. 2A) Super selective embolization was performed of feeders involved in the auricular cascade with penetration into the draining veins, nidus, and distal dedicated feeding arteries. Concurrently, the ear was packed in ice to stop flow to the normal tissue. One-tenth of a cc of non-opacitied NBCA was used to minimize the mass of embolic material and discoloration. This led to the total obliteration of the AVM.

Follow-up, (Fig. 2B) shows obliteration of the AV shunting. Additional angiography is indicated in 6-12 months to confirm obliteration.
Fig. 1A Posterior aspect of Left Ear.
Fig. 1B Two weeks after embolization the inflammation is gone and the shunt gone by Doppler.
Fig. 1B Two weeks after embolization the inflammation is gone and the shunt gone by Doppler..
Fig. 2B Total angiographic obliteration of AVM and fistula with sparing of the Helix cascade( as seen on late films)
Key Points:
  1.  Extra-cranial AVMs can become quite active, and can grow with trauma, puberty, or pregnancy.
  2. Normal tissue blood flow is controlled by tissue temperature, whereas pathological shunts seen in AVM’s are fixed. At temperatures below 20C, there is virtually no flow to normal tissue.It is possible to take advantage of this to spare the normal tissue and target the shunts as in this case.
  3. Angiographic follow-up is needed in all AVM treated cases once the non-invasive imaging has been negative for 6-12 months as it is the only way to confirm cure.
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NEUROLOGICAL SURGERY, P.C.
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