The role of medical imaging in the management of a complex prehelix fistula in children: A case report

A prehelix fistula, or periauricular sinus, is a benign congenital malformation, often asymptomatic, and it is usually recognized by a tiny opening located in front of the helix [1]. It shows up during the sixth week of gestation, when the first and second branchial arches come together [2]. Its incidence is estimated around 0.1–0.9% in the United States, 0.9% in England, about 2.5% in Taiwan, and can reach up to 4–10% in some parts of Africa [3].

Now, the reason it can be a bit complicated is that the lesion involves deep, branched fistulous tracts, so the surgical removal becomes harder, with a notable risk of recurrence [4]. Because of that, medical imaging really matters, since it helps to map the fistulous course and allows a more suitable surgical approach to be chosen.

So, this report describes a right prehelix fistula managed in the Democratic Republic of the Congo. In particular, in the ENT department of Saint Joseph Hospital in Kinshasa, among 484 otological procedures recorded from 2007 to 2024, prehelix fistula excision represented only 0.8% of all cases, including this difficult one [5]. The aim of this study was to show the added value of medical imaging for handling a complex prehelix fistula.

This clinical observation is about an 11-year-old girl who was admitted to the ENT unit of Saint Joseph Hospital in Kinshasa/Limete because she had recurrent purulent otorrhea on the right side. At the same time, there was a swelling in front of the tragus that seemed to have been there for several years.

Her background includes a cranial suture malformation noticed at birth and seizures, later diagnosed as epilepsy. She was treated well with Depakine, and also Gamalate. In the family, her father had diabetes along with hypertension. Her mother, as reported, had taken an ovulation inducer before conception, namely clomiphene citrate.

When she was admitted, she showed a small opening in front of the left helix, and near it there was a painful swelling, tender, and kind of fluctuating to touch. Otherwise, the rest of the ENT exam was basically normal.

So the working diagnosis was a prehelix fistula, complicated by a recurrent pretrageal abscess. The treatment involved surgery: incision and drainage of the pretrageal abscess. This was completed with antibiotics, lincomycin and niflumic acid suppositories. After that, the inflammatory and infectious episode settled.

Finally, a secondary prehelix sinusectomy was done, and it was performed without doing any prior fistulography.

The postoperative course was pretty much a remission for around five months, then after that there were three episodes of recurrence within one year, all managed with antibiotic therapy and also incision and drainage of the abscesses, and later some steroid anti-inflammatory drugs too.

Because these inflammatory infectious relapses kept coming back, a routine fistulography was done, this showed a transverse fistulous tract that seemed to be intrapetrous, going upward and kind of overhanging the mastoid cells (Figure 1).

Medical treatment was maintained for one year, after each infectious episode, until recovery.

A brain magnetic resonance imaging (MRI), done because of seizure activity, showed a right parieto-occipital communicating porencephaly, along with hemispheric collapse and meningeal contrast enhancement yet no formal identification of a fistulous tract (Figure 2).

Illustration of the brain MRI performed

On the contrast-enhanced sequence (E and F) we see right temporo-parieto-occipital leptomeningeal contrast enhancement that matches leptomeningitis, as a result of disruption of the blood brain barrier, so it is sort of a blood–brain barrier (BBB) issue.

Because there was no active fistula reoperation was not pursued, and in a sense there was nothing target. Currently, two years have passed without any recurrence, so the fistula looks inactive anymore (no fistulous tract was found on MRI). Pure-tone audiometry demonstrated normal hearing, and renal plus pre-helical ultrasound showed, respectively, a normal urinary tract, and fibrosis in the pre-helical region. That said, the patient still has academic delays, mainly because of memory difficulties.

The aim of this article was to show how medical imaging can be really useful when dealing with a complicated prehelix fistula and, in this situation, with management that involved recurrence as well.

Even if diagnosing a prehelix fistula is usually based on clinical observation, and routine imaging is not always needed, once the case gets complicated and starts coming back, the usefulness of medical imaging becomes quite obvious.

In fact, the literature describes that several imaging studies are recommended. For example, high resolution ultrasound is often the preferred option, particularly in children, because it helps confirm the diagnosis, clarify the connection with the superficial temporal artery and cartilage, and also detect other related anomalies when certain syndromes are involved [6]. Computed tomography (CT) scanning with contrast injection directly into the fistula is also helpful, mainly for surgical planning of complex lesions, since it can indicate how deep the fistula tract goes [7]. As for MRI, it is the test of choice when the goal is precise mapping of the fistula tunnel and when you need to distinguish it from malformations of the first branchial cleft [8].

In the current clinical case, all three examinations were carried out postoperatively, and they gave very accurate details. During active phase fistulography, using contrast injection, demonstrated a long, deep fistula tract, which matches the idea that the lesion was complex, and it also explains why recurrence occurred after the surgery. Clearly, the surgical approach, ideally, should include full excision of the fistula tract [3],[4]. Two surgical approaches are described: the supra-auricular approach via local excision of the sinus and sinusectomy [3]. Tan et al. [3], 2005 note that the first approach is presently preferred, since it gives the best results overall.

Meanwhile, MRI has also shown an association between this congenital malformation and brain malformations. In particular, it has been described that prehelix fistula might come alongside other conditions or syndromes in about 3% to 10% of patients, especially deafness and branchio-oto-renal syndrome [9], even though a link with brain malformations has not been reported in the available literature demonstrating the value of medical imaging. Also, renal ultrasound plus pure-tone audiometry came back normal.

Finally, MRI was used to confirm that the issue had resolved, showing no fistulous tract. Ultrasound likewise demonstrated perilesional fibrosis, which suggests the fistula was no longer active. The learning difficulties and memory problems experienced by the patient are consistent with MRI findings, particularly the localized parenchymal destruction of cerebral parenchyma.

This clinical case report demonstrates that medical imaging is a cornerstone of the surgical strategy in cases of recurrence or diagnostic uncertainty regarding a prehelix fistula. It enables the complete excision of the fistula tract and is essential for postoperative surveillance and the assessment of associated congenital anomalies.