Ecchordosis Physaliphora and Posttraumatic Headache: A Diagnostic Challenge in Neurotrauma

Ecchordosis physaliphora (EP) is a rare entity of the central nervous system (CNS) originating from ectopic remnants of the notochord. During embryonic development, the notochord induces the formation of the neural tube through molecular signals such as Sonic Hedgehog. While it typically degenerates and persists only in the nucleus pulposus of the intervertebral discs, its remnants may localize in abnormal sites. EP most commonly occurs in the retroclival prepontine cistern, although it can appear anywhere along the notochordal axis, from the base of the skull to the sacrum. This benign lesion, with a unique histology and specific location, is usually asymptomatic, making it a diagnostic challenge for clinicians and researchers.[1] [2]

The clinical manifestations of EP include headache, cerebrospinal fluid (CSF) rhinorrhea, diplopia, sixth cranial nerve palsy, and hemiparesis. Less frequent symptoms, such as dizziness, tinnitus, and paresthesia, may also occur. Neuroimaging is the primary diagnostic tool and allows differentiation from other neurological conditions, aiding in the decision between conservative management with serial magnetic resonance imaging (MRI) or surgical resection with biopsy. In more severe cases, EP may progress to malignant chordoma, necessitating timely surgical intervention.[2] A case of EP discovered as an incidental finding in a patient with posttraumatic headache secondary to neurotrauma is presented below.

Clinical Case

A 55-year-old patient was evaluated in 2020 for a universal headache secondary to mild head trauma sustained during a traffic accident. As part of the evaluation, an MRI was performed, revealing a cystic retroclival cisternal lesion on the right measuring 13.1 mm by 8.25 mm, without contrast enhancement ([Fig. 1A, B]). These images were diagnostic for EP, and the patient improved with symptomatic treatment.

Fig. 1 MRI images with and without contrast, in (A) T1 and (B) DWI (diffusion-weighted imaging) from 2020, and (C) T1 and (D) DWI from 2024, showing a well-defined cystic lesion to the right of the midline, toward the dorsal aspect of the clivus. The lesion appears hypointense on T1-weighted images, with no evidence of diffusion restriction on the DWI sequence. Post-contrast T1-weighted images did not show enhancement of the lesion, and the rest of the brain parenchyma showed no significant alterations. MRI, magnetic resonance imaging.

Annual follow-up MRI was conducted until 2024, confirming the morphological stability of this finding, with very minimal variation in its original dimensions ([Fig. 1C, D]).

[Fig. 1] shows MRI images with and without contrast, in A (T1) and B (DWI [diffusion-weighted imaging]) from 2020, and C (T1) and D (DWI) from 2024, showing a well-defined cystic lesion to the right of the midline, toward the dorsal aspect of the clivus. The lesion appears hypointense on T1-weighted images, with no evidence of diffusion restriction on the DWI sequence. Post-contrast T1-weighted images did not show enhancement of the lesion, and the rest of the brain parenchyma showed no significant alterations.

Discussion

EP was first described in 1856 by Luschka, who referred to it as “gelatinous enchondroma,” and it has historically been associated with remnants of the notochord. In his 1857 study, Virchow suggested that EP could originate from these embryological structures, and later, in 1894, Ribbert coined the definitive term.[3] [4]

Today, EP remains an incidental finding in approximately 2% of autopsies.[1] However, it may cause mass effect and compression of the brainstem or cranial nerves.[5] In this case, the incidental finding of EP in a patient with posttraumatic headache presents a significant diagnostic challenge, as posttraumatic headache is a common complaint and is not typically associated with rare lesions like EP.

Previous studies have documented the incidence of EP in MRI series. Mehnert and colleagues found EP in 1.7% of cases as an incidental finding in 300 MRIs,[6] while Gökoğlu and associates reported that 37.5% of EP cases were detected incidentally during imaging studies for various indications.[7] In a systematic review of 60 cases, Gupta and colleagues concluded that EP is more common in women (62%) and its most frequent location is the prepontine region (77%), although it can also be found in other areas such as the posterior sphenoidal sinus.[2]

EP can be easily confused with other more common pathologies, especially in patients with neurotrauma. This underscores the importance of considering comprehensive differential diagnoses in cases of posttraumatic headaches to avoid misdiagnosis or delays in appropriate treatment. Although EP generally does not cause significant symptoms, in this case, the posttraumatic headache was a confounding factor, as the incidental lesion was not directly related to the patient's clinical symptoms. However, serial follow-up through imaging, as in this case, allows for the exclusion of potential complications, such as lesion growth or progression to malignant chordoma.[8] [9]

Regarding imaging, EP appears hypointense on T1 and may be hyperintense on T2, and its appearance on T2-FLAIR follows the signal of CSF, facilitating its identification on MRI. Unlike chordoma, EP does not show contrast enhancement, helping to differentiate it from other malignant or more aggressive lesions in the prepontine region.[5]

This case highlights the importance of identifying incidental findings such as EP in patients with neurotrauma. Although EP is a benign lesion, its accurate identification can prevent misdiagnoses and help provide appropriate follow-up to ensure that no future complications arise. Including EP in the differential diagnosis is crucial for clinicians managing patients with posttraumatic headaches, as the lesion, though rare, can easily be mistaken for other more common pathologies.

Conclusion

EP is a rare lesion of the CNS that, although generally asymptomatic, should be considered in the differential diagnosis of patients with posttraumatic headache and other neurological manifestations. Its incidental identification through MRI in patients with neurotrauma underscores the importance of recognizing uncommon findings that could be confused with more frequent conditions. Despite its benign nature, an accurate diagnosis is crucial to avoid unnecessary interventions and ensure appropriate follow-up.

Conflict of Interest

None declared.

• References

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Publication History

Article published online:
26 March 2025