Working Diagnosis:
Left transverse venous sinus thrombosis

Treatment:
Anticoagulation initially with LMWH or unfractionated IV heparin, followed by transition to DOAC or vitamin K antagonist

Outcome:
The patient's first outpatient neurology follow-up occurred 2 weeks after her discharge from the hospital. At that time, neurology repeated MR and MRV of the brain, which showed significant improvement in the left transverse venous sinus thrombosis. They recommended the patient continue with her anticoagulation and follow up again in another 3 months. At the next follow up, neurology again repeated MR and MRV of the brain, but this time they showed no significant improvement since the last round of imaging. Neurology referred the patient to hematology, who recommended the patient remain on lifelong anticoagulation, with the option to decrease to Eliquis 2.5 mg twice daily or full dose aspirin daily. Hematology repeated her hypercoagulability workup as well as a genetic workup, all of which were negative. The patient continued to follow up with hematology 6 months later, at which point she was cleared to follow up only as needed, assuming she continues her anticoagulation as instructed. As the patient did not participate in any high risk contact sports, she was cleared to participate in all other activities after an extensive conversation of shared decision making. Since then, she has not had any repeat clotting events or recurrence of symptoms.

Author's Comments:
Concussions are defined as mild traumatic brain injuries with no abnormalities on standard neuroimaging [2]. Patients may be diagnosed with concussion or mild traumatic brain injuries on the basis of negative CT alone, as additional imaging such as MR are more difficult to obtain. Thus, knowing when to suspect non-concussion etiologies and the need for additional imaging is crucial in the management of patients such as ours, in whom an erroneous diagnosis of concussion would have been potentially fatal. Although there are no universal diagnostic criteria for concussions [2], certain atypical symptoms may raise suspicion for alternative diagnoses. In our patient, the intractability and severity of her headache, changes with recumbency, and recurrence of headache after 4 days without symptoms suggest the need for further testing.
Cerebral sinus venous thromboses (CSVT) are rare, with an incidence of 5 per million [3]. However, our patient had several of the most common risk factors, including age under 55, female sex, oral contraceptives, infection (i.e. pansinusitis), and head injury (i.e. posterior head strike) [1,3]. The most common locations for CSVT are the superior sagittal sinus (62%), left transverse sinus (44.7%), and right transverse sinus (41.2%) [1]. Headache is by far the most common symptom (88.8%), typically diffuse and worsened with recumbency or Valsalva, but a minority may present with a thunderclap or migraine-like headache [3]. Up to 25% may have isolated headaches without neurologic symptoms [3]. Symptom onset is usually acute (30 days), making this otherwise rare diagnosis still a possibility warranting consideration even a month after the index event [1].
Diagnosis is usually made with CT/CTV or MRI/MRV, with no significant differences in sensitivity or specificity between these imaging studies, but if these are inconclusive, cerebral angiography should be pursued [3]. Anticoagulation is the standard of care, with initial treatment usually involving LMWH or unfractionated IV heparin for 5-15 days before transitioning to either DOAC or vitamin K antagonist. Anticoagulation duration and type thereafter vary depending on whether the CSVT was provoked and whether the patient has prothrombotic conditions. Monitoring may involve repeat imaging in 3-6 months, however its utility in informing anticoagulation duration remains uncertain [3].
Regarding outcomes, the ISCVT study reported 79% of patients had complete recovery at median 16 months, while 8% died and 2% had recurrent CSVT [1]. However, there still remains significant potential impact on quality of life, given the high prevalence of residual symptoms affecting cognition, mood, and headaches. The risk of VTE after initial CVT is about 1-4% per year, and repeat CVT about 1-2% per year [3]. Death or dependence occurs in 10-15% of cases even with treatment [3].

Editor's Comments:
Please note, author and editor commentary have been combined above as a collaborative work.

References:
[1] Ferro JM, Canhao P, Stam J, Bousser MG, Barinagarrementeria F; ISCVT Investigators. Prognosis of cerebral vein and dural sinus thrombosis: results of the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT). Stroke. 2004 Mar;35(3):664-70. doi: 10.1161/01.STR.0000117571.76197.26. Epub 2004 Feb 19. PMID: 14976332.

[2] Patricios JS, Schneider KJ, Dvorak J, Ahmed OH, Blauwet C, Cantu RC, Davis GA, Echemendia RJ, Makdissi M, McNamee M, Broglio S, Emery CA, Feddermann-Demont N, Fuller GW, Giza CC, Guskiewicz KM, Hainline B, Iverson GL, Kutcher JS, Leddy JJ, Maddocks D, Manley G, McCrea M, Purcell LK, Putukian M, Sato H, Tuominen MP, Turner M, Yeates KO, Herring SA, Meeuwisse W. Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport-Amsterdam, October 2022. Br J Sports Med. 2023 Jun;57(11):695-711. doi: 10.1136/bjsports-2023-106898. PMID: 37316210.

[3] Saposnik, Gustavo and Bushnell, Cheryl and Coutinho, Jonathan and Field, Thalia and Furie, Karen and Galadanci, Najibah and Kam, Wayneho and Kirkham, Fenella and McNair, Norma and Singhal, Aneesh and Thijs, Vincent and Yang, Victor. (2024). Diagnosis and Management of Cerebral Venous Thrombosis: A Scientific Statement From the American Heart Association. Stroke. 55. 10.1161.

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