Syringohydromyelia, syringobulbia and syringocephaly associated with Chiari – I malformation: A case report

Abstract

Syringohydromyelia, syringobulbia, and syringocephaly are rare manifestations of Chiari-I malformation (CM-I), each resulting from disrupted cerebrospinal fluid dynamics. While syringomyelia is commonly associated with CM-I, the rostral extension of syrinx cavities into the brainstem (syringobulbia) and cerebral parenchyma (syringocephaly) is very rare, with limited cases reported globally. This case report describes a 40-year-old woman presenting with progressive neurological deficits, including hemiparesis, sensory disturbances, and bulbar symptoms. Magnetic resonance imaging revealed CM-I with a syringohydromyelic cavity extending from the cervicomedullary junction to the thoracic spinal cord, syringobulbia involving the brainstem, and syringocephaly affecting the left cerebral hemisphere, internal capsule, and basal ganglia. Following posterior fossa decompression, the patient experienced significant neurological improvement, including restored motor function and resolution of intracranial edema, although the cervical syrinx cavity remained stable. This case demonstrates the importance of early diagnosis and surgical intervention in managing these rare yet debilitating complications of CM-I, highlighting the potential for improved outcomes despite the complex and extensive nature of these lesions.

Introduction

Syringohydroomyelia is a neurological disorder in which a fluid-filled cyst (syrinx) forms within the spinal cord, either in the central canal or extending into the cord's tissue [1]. It is commonly associated with hindbrain malformations, particularly Chiari-I malformation (CM-I), and is observed in approximately 35% of patients with symptomatic CM-I [2]. In rare cases, the fluid cavity extends rostrally into the brainstem, a condition known as syringobulbia [3,4]. Even more rarely, the syrinx cavity may extend further rostrally into the cerebral parenchyma, a phenomenon referred to as syringocephaly [5]. Reports describing syrinx involvement extending from the spinal cord to regions such as the basal ganglia, internal capsule, and cerebral cortex remain exceedingly scarce [[5], [6], [7], [8], [9], [10], [11]]. While CM-I is a common association with these findings, it is important to differentiate it from other conditions that can mimic its imaging features, such as cerebrospinal fluid (CSF) hypotension and idiopathic intracranial hypertension (IIH), which can also result in low-lying and peg-shaped tonsils. This case report presents a 40-year-old woman with CM-I, syringomyelia, and syringocephaly, resulting in progressive neurological deficits.

Case presentation

A 40-year-old right-handed woman presented with a 4-month history of progressive right-sided numbness, weakness, and intermittent pain. Her symptoms began as mild numbness in her right hand, which extended to her arm and leg over weeks. By the third month, she experienced significant functional limitations, including an inability to perform tasks like writing and walking due to weakness in her right extremities. She also developed urinary incontinence, balance disturbances, intermittent voice changes, choking episodes while swallowing liquids, and burning pain in her right extremities that disrupted her sleep. She had no other known medical conditions, allergies, and was not taking any regular medications. Both social and family histories were unremarkable.

On admission, the patient appeared distressed but had stable vital signs. She required assistance to walk, displaying a hemiplegic gait. Neurological examination revealed hypertonia in the right upper and lower extremities with muscle strength graded at 3/5. Brisk deep tendon reflexes were noted, along with clonus, a right-sided Babinski sign, and a positive Hoffman’s sign. Sensation to light touch and pinprick was diminished in the affected extremities. The left extremities showed normal findings, and other neurological and systemic examinations were unremarkable except for a poor gag reflex.

Routine laboratory studies were within normal limits.

The Magnetic resonance imaging (MRI) of the brain and cervical spinal cord revealed a crowded foramen magnum and cerebellar tonsillar descent with a peg-like tip lying 1.1cm below the basion-opisthion line. There was an associated long segment cervical cord T2 hyper intense syringohydromyelic cavity spanning from cervicomedullary junction to lowest included level in the scan (T5). Additionally, there was a well-defined, longitudinally oriented T1 hypointense and T2 hyperintense intracranial cystic lesion, showing suppression on FLAIR involving the left frontal centrum semiovale, left posterior limb of internal capsule, the anterior parts of midbrain, pons and medulla. The lesion does not show post contrast enhancement or diffusion restriction. There is a surrounding perilesional vasogenic edema with associated mass effect, effacing the left lateral ventricle. No obvious communication was noted between this lesion and the cervical cord syrinx or the fourth ventricle (Fig. 1) findings consistent with Chiari malformation type I (CM-I) associated with syringomyelia, syringobulbia and syringocephaly.

Fig. 1.

: Initial brain MRI Axial T2W (A), coronal T2W(B) and sagittal T2W(C&D), axial FLAIR (E&F), axial contrast enhanced T1W(G) images of the brain and spine shows a well-defined, lobulated, longitudinally oriented cystic cavity involving left centrum semi ovale (white arrow), basal ganglia, posterior limb of internal capsule (black arrowheads), brainstem (black arrow) and cervical cord (white arrowhead), with surrounding vasogenic edema.

The patient underwent posterior fossa decompression (PFD) to address the Chiari-I malformation and associated syringohydromyelia, syringobulbia, and syringocephaly. The procedure involved suboccipital craniectomy to decompress the crowded posterior fossa, C1 laminectomy to relieve pressure at the cervicomedullary junction, and duraplasty with a graft to expand the dural sac and restore cerebrospinal fluid flow.

Follow up brain MRI done 4 months postoperatively demonstrates sub occipital craniectomy defect with minimal overlying pseudomeningocele which represents postoperative CSF leak. There is a significant shrinkage of the previously visualized intracranial cystic lesion involving the left cerebral hemisphere and brainstem with only a small slit-like cavity remaining. There is also resolution of surrounding perilesional edema and associated mass effect. However, the cervical syrinx remained stable in size (Fig. 2).

Fig. 2.

Post-op follow up brain MRI, axial T2W (A) and sagittal T2W(B) images shows suboccipital craniectomy defect with overlying pseudomeningocele (arrow heads), marked interval radiologic reduction in the intracranial cystic cavity with remaining slit like cavity in the posterior limb of internal capsule and brain stem (white arrow) and relatively stable cervical syringomyelic cavity(black arrow).

Postoperatively, the patient showed marked improvement in motor function, regaining independent ambulation, improvement of gag reflex and hand functionality. She was discharged with a management plan that included physiotherapy for motor rehabilitation and pregabalin for neuropathic pain, along with regular follow-up at a neurosurgical clinic.

Discussion

Chiari malformation type I (CM-I) is a neurological disorder characterized by the downward displacement of the cerebellar tonsils through the foramen magnum, leading to compression of the cervicomedullary junction and disruption of cerebrospinal fluid (CSF) flow [12]. It is commonly associated with syringomyelia, a fluid-filled cyst in the spinal cord caused by altered CSF dynamics [13]. In rare cases, the syringomyelic cavity extends into the brainstem (syringobulbia) and even further rostrally into the brain (syringocephaly) [14]. While typically linked with hindbrain abnormalities or neoplasms of the posterior fossa and spinal canal, it can also occur in isolation following conditions like meningitis [[14], [15], [16], [17], [18], [19], [20]]. A study by Menezes et al. evaluating 326 pediatric patients with chiari-I malformation found that 13 (4%) of pediatric CM-I patients had syringomyelia or syringobulbia, with only 1 case showing extension to the cerebrum (syringocephaly) [21]. While CM-I is a common association, differentiating it from CSF hypotension (positional headaches, meningeal enhancement) and IIH (papilledema, elevated CSF pressure) is crucial. Clinical evaluation, fundoscopy, and lumbar puncture aid in distinguishing these conditions. During the initial radiologic assessment, alongside the clearly visible Chiari-I malformation and syrinx in the posterior fossa, several potential diagnoses were considered for the cystic intracranial lesion. These included cystic astrocytoma, neuroglial cyst, and large perivascular spaces. A cystic astrocytoma, especially pilocytic astrocytoma, typically presents with a strongly enhancing solid component, and there is usually little to no surrounding vasogenic edema. A high-grade astrocytoma with central necrosis would also show an enhancing solid component, along with signs of high cellularity, such as areas with restricted diffusivity [22]. Neuroglial cysts are congenital, unilocular cysts lined with glial cells, typically found in the frontal lobe, and do not show contrast enhancement or surrounding edema [23]. Giant tumefactive perivascular spaces generally appear as clusters of cysts of varying sizes that follow CSF signal. These are most commonly located along the lenticulostriate arteries, just above the anterior perforated substance, near the anterior commissure, and less frequently in the centrum semiovale [24]. Complete thoracolumbar MRI was not done to visualize the caudal extent of the syrinx.

Symptoms of syringobulbia and syringocephaly vary depending on the location of the syrinx, often involving unilateral neurological deficits such as extremity weakness, headache, diplopia, swallowing difficulties, dizziness, and sleep apnea [14,21,25]. Menezes et al. reported that all 13 patients with syringobulbia had multiple cranial nerve palsies, primarily affecting the vagus and glossopharyngeal nerves [21]. While early imaging techniques often struggle to demonstrate these extensions due to the narrow and slit-like nature of the cavities in the brainstem [26], modern MRI sequences offer improved visualization.

The mechanisms behind syringobulbia and syringocephaly are not well understood, but some theories include acute CSF pressure changes forcing fluid into the brainstem through the path of least resistance, or a dilated spinal central canal leading to fluid egress into the brainstem via perivascular spaces [6,13,27].

Posterior fossa decompression (PFD) is the standard treatment for symptomatic CM-I, involving suboccipital craniectomy, C1 laminectomy, and duraplasty to relieve compression and restore normal CSF flow [28,29]. In our patient, decompression resulted in significant improvement in motor function and resolution of perilesional edema, although the cervical syrinx remained stable. Similarly, in Menezes' study, syringobulbia resolved postoperatively in all patients, but the syringomyelia persisted longer, requiring ongoing monitoring to prevent recurrence or progression of symptoms [21,30].

Conclusion

Syringohydromyelia, syringobulbia, and syringocephaly are rare but possible manifestations of Chiari-I malformation, arising from disrupted cerebrospinal fluid dynamics. Surgical intervention, such as suboccipital decompressive craniectomy, can result in significant neurological improvement, particularly in motor function, while ongoing monitoring is essential for managing residual syrinx cavities.

Author contributions

All authors contributed to this research and read and approved the final version of the manuscript.

Patient consent

Written informed consent was obtained from the patient for anonymized patient information to be published in this article.