November 7, 2024
A 17-year-old adolescent boy comes to the emergency department after a motorcycle crash, with intense pain in the right arm and shoulder, decreased sensitivity, and incapacity to move wrist and fingers.
Posttraumatic pseudomeningocele and nerve root avulsion
- Background:
- A pseudomeningocele is an abnormal perivertebral circumscribed fluid collection of CSF, which communicates through the neural foramen or through a vertebral defect, associated with dural tear after spinal surgery (durotomy) or nerve root avulsion and tear of nerve root sleeve during spinal trauma. Most adult brachial plexus injuries are posttraumatic, caused by traction in situations of high-energy forces (abduction or downward displacement of the arm), with avulsion of one or more nerve roots from spinal cord. Nerve root avulsion is classified as preganglionic (lesion central to dorsal root ganglion) or postganglionic (injury peripheral to ganglion). The most common signs/symptoms are localized soft tissue swelling, pain, and paralysis of ipsilateral limb.
- Clinical Presentation:
- Intense pain in the right arm and shoulder, with edema
- Decreased sensitivity and incapacity to move wrist and fingers
- Shoulder and arm radiographs may be normal
- Key Diagnostic Features:
- CT findings include an epidural and/or paravertebral fluid collection, which can be associated with vertebral fracture, and, if chronic, can be associated with osseous remodelling and foraminal widening.
- An MRI will show a fluid collection, epidural and/or paravertebral, well-delineated, with the epidural fat providing a natural contrast to the extent of the collection. The collection is lacking of neural elements, is hypointense on T1, hyperintense on T2 and STIR, with no enhancement after T1 contrast.
- A fast-spin-echo T2-weighted sequence can be helpful to define dural margin and presence or absence of nerve roots, which are absent in cases of nerve root avulsion.
- Differential Diagnosis:
- Epidural or paravertebral hematoma, which is a collection of blood, hyperdense on CT in acute stages, and will not follow the CSF signal on every MR sequence.
- Epidural or paravertebral infected collection, as it is seen in spondylodiscitis, will have a marked enhancement, with peripheral enhancement if an abscess, or diffuse if a phlegmon.
- Nerve root sleeve cysts are incidental findings and can be large, with intact nerve roots peripherally displaced by cyst.
- Lateral meningocele can mimic pseudomeningocele but contains neural elements associated with Marfan or Ehler-Danlos syndromes and NF-1.
- Treatment:
- Injury level is critical to treatment planning and prognosis, because the integrity of nerve roots is key for surgical decision.
- Preganglionic avulsions are normally not feasible to repair surgically, and thus have a worse prognosis.
- Postganglionic avulsions are surgically managed, with excision of damaged segment and nerve autograft between nerve ends, and have a better prognosis.
- In the patient with preganglionic avulsions and pseudomeningocele, a conversative approach was followed with medical treatment of symptoms, physiotherapy, and small improvement.
