Introduction

Post-traumatic syringomyelia (PTS) is the growth of a cavitation in the spinal cord after a vertebral lesion with or without an injury of the cord. Clinically, it is characterised by dissociated sensory reduction, signs of lower motor neuron involvement (usually limited to upper limbs and trunk), the involvement of descending and ascending tract functions and alterations of skin trophism. The cavity may extend into the brainstem and produce the syndrome of syringobulbia with involvement of the cranial nerves and of the reticular substance. The neurological disturbances associated with syringomyelia and syringobulbia depend on the localisation, dimension and extension of the spinal cord cavitation and subsequent gliosis [1].

We report a case of PTS with syringobulbia in a patient without symptoms.

Case report

A 36-year-old woman suffered a T6 vertebral fracture with spinal cord injury (SCI) because of a sport accident (fall from a horse) in 1996. The injury resulted in an AIS A T7 paraplegia. She underwent non-surgical treatment with immobilisation for 4 months. Soon after the accident, she developed pain in the C7–C8 dermatomes without sensory or movement deficits. The woman underwent rehabilitation resulting in complete wheelchair independence. She returned to a full social and vocational life and returned to regular swimming for exercise. A few months prior to the magnetic resonance imaging (MRI) examination, she developed neck and left shoulder pain without other symptoms.

MRI images of the thoracic and cervical spine showed a large cavity involving the cord beneath T6 and the medulla (Figs. 1, 2). Septations were present at both the spinal cord and the medulla levels (Figs. 1, 2). With regard to vertebral status, the MRI showed the presence of severe kyphosis at the fracture level together with spinal cord compression (Fig. 3).

Fig. 1: MRI of the brainstem.
figure 1

T2-weighted transverse MRI of the brainstem showing the extension and entity of the syringobulbia.

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Fig. 2: MRI of the cervical spinal cord and brainstem.
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T1-weighted sagittal MRI of the spinal cord and brainstem showing the extension and entity of the syringomyelia and syringobulbia.

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Fig. 3: MRI of the thoracic spinal cord.
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T2-weighted sagittal MRI of the thoracic spine showing the kyphosis of the spine.

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The neurological examination showed the pre-existing picture of complete paraplegia. The sensory examination of the dermatomes beneath the lesion level did not show any sensory loss with the exception of loss of pain sensation in the C8 dermatome. With regard to muscle testing, the individual did not show any strength loss. Triceps reflex was reduced on the left arm. Cranial nerve examination did not show any deficit and she did not report any cardiac or respiratory problems.

The subject underwent neuro-surgical examination, but surgical intervention was determined inappropriate because of the presence of septations that make it difficult to void the cavity with a shunting procedure and because of the high risk of bleeding with concurrent cavity enlargement and acute cardio-respiratory insufficiency.

The symptoms she presented disappeared with a short course pharmacological treatment with non-steroid anti-inflammatory drugs and muscle relaxants.

Discussion

The incidence of PTS is reported to be increasing and varies based on whether the diagnosis is purely clinical or instrumental (mainly by means of MRI) [2]. It has been calculated that if all subjects with a spinal injury undergo an MRI examination between 1 and 30 years after the lesion, 21–28% of them will be found to present a syringomyelia. However, syringomyelia is symptomatic in only 1–9% of individuals with SCI [3].

Regarding pathogenesis, the formation of the cavity may be related to several different factors [3]. The cascade of inflammatory reactions triggered by the trauma could result in oedema and possibly in cavity formation. The evolution of bleeding phenomena within the spinal cord may lead to a cystic cavity. Ischaemic phenomena, triggered by the primary injury or subsequent arachnoiditis, may also play a role in cavity formation as post-traumatic cavities are often reported to be placed in the vascular watershed regions of the cord. Cavity expansion may be due to a disproportion between fluid inflow and outflow, with ‘slosh’ and ‘suck’ mechanisms [2, 3]. The development of PTS has been reported to be correlated with spinal canal stenosis both in the sagittal and in the axial plane. This may prove that a lack of reduction of the vertebral lesion and the persistence of spinal cord compression may be related to the genesis of the cavity [4]. However, this hypothesis is questioned by a recent study that did not find a relationship between the initial management of spinal cord lesion and the incidence of PTS [5, 6]. Therefore, additional studies on the aetiology of this complication are required to investigate this issue because it may influence the future management of individuals with SCI.

PTS may occur between the first months and several years after SCI with gradual symptomatic progression. However, a rapid worsening due to bleeding into the cavity has been described. Common PTS symptoms include ache at or above the level of lesion; a loss of sensation, which is classically defined as dissociated (a loss of pain and cold and heat sensation with light touch and proprioception sparing) in the segments above the lesion, progressive muscle weakness and reflexes weakening; signs of autonomic dysregulation; and Horner’s syndrome [3].

The syrinx may extend into the brainstem (syringobulbia) and produce symptoms and signs due to the involvement of cranial nerves [1, 3] or reticular formation with involvement of the cardiovascular and respiratory functions [7]. A positive correlation seems to exist between syrinx length and neurological deterioration, whereas cyst diameter did not seem to be of importance [2].

The case we presented is in some ways typical of PTS syndrome. This woman had an SCI 11 years before the finding of PTS. At the moment of the trauma she underwent non-surgical treatment that resulted in a vertebral stabilisation with kyphosis and persisting spinal cord compression. She did not show any sign or symptom of neurological deterioration due to the cavity, as the pain she presented and which was the cause of MRI examination disappeared after a short-term treatment with non-steroid anti-inflammatory drugs and muscle relaxants; therefore, the symptomatology was likely un-related to the presence of the syrinx, but to a contracture of the shoulder and neck muscles. What is surprising in the present case is the dimension of the cavitation that ascends from the fracture level up to the cervical spinal cord and to the medulla, occupying the largest part of these structures. As it has been demonstrated, there is usually a relationship between the length of the syrinx and neurological deterioration, [2] and cardio-respiratory symptoms may occur due to the involvement of the intermediate reticular formation [7], therefore, we would expect a much more severe clinical picture.

Several procedure have been proposed for treatment of PTS, including shunting of the cavity [8, 9], arachnoidolysis and duroplasty [10], decompression of the spinal cord [11], spinal cord untethering alone or associated with other techniques [12]. However, surgical treatment is recommended mostly in subjects with developing symptoms [13]. Furthermore, a number of SCI subjects with syringomyelia are refractory to surgical treatment [14] or present a recurrence of the syrinx requiring re-intervention [15]. Based on this evidence, on the presence of septations in the cavity and on the high risk of bleeding after surgery, it was decided not to operate on the patient, who is undergoing MRI and clinical follow-ups that, until now, have demonstrated the stability of the radiological and clinical picture.