Delayed unrelated presentation of a lumbar burst fracture consequent to a remote episode of a single convulsive seizure: A diagnostic challenge

Abstract

Non-traumatic vertebral fractures occurring as a sole consequence of the violent muscle forces generated during the first episode of a GTCS(generalized tonic clonic seizure) in a previously healthy non-epileptic individual are very rare. Being clinically asymptomatic they are easily overseen at the time of initial presentation due to their rarity of occurrence and the presence of potentially distracting factors in the post-ictal phase. We present a 52-year-old healthy non-epileptic male who presented with unrelenting back pain and neurodeficit secondary to a four-month-old unstable burst fracture of the first lumbar vertebra sustained during an isolated single episode of a witnessed GTCS. A detailed inquiry revealed no history of a significant traumatic event either during the convulsive episode or thereafter. A meticulous history taking, a thorough clinical and neurological examination combined with a comprehensive radiological evaluation established the unusual etiology of the fracture and the presence of a thoracolumbar kyphotic deformity with compression of conus medullaris. A detailed neurological, and laboratory work-up, confirmed no attributable organic or metabolic cause for the seizure. His BMD(Bone Mineral Density) was normal. Patient was managed with posterior instrumented deformity correction by a posterior column shortening osteotomy, neural decompression and fusion of D12-L1 facets. Patient had complete neurological recovery with good clinical and functional outcomes at 28-months follow-up. A few cases of seizure-induced non-traumatic spinal fractures have been published in literature. A majority of these fractures occurred in individuals with either seizure-provoking risk factors (epileptics with recurrent seizures, brain tumors, drug overdose/withdrawal, metabolic disorders, or electrolyte imbalance) or in those with an increased susceptibility to fracture due to decreased BMD. This case demonstrates the rare occurrence of a non-traumatic vertebral fracture during the first episode of a GTCS in an otherwise healthy non-epileptic individual with normal BMD and no seizure-provoking risk factors. This is the first case report of a delayed unrelated presentation of a non-traumatic lumbar vertebral fracture with complications (spinal deformity and neurodeficit) consequent to a remote episode of a single convulsive seizure. It emphasizes the need for a high index of clinical suspicion,a meticulous history taking, thorough musculoskeletal and neurological examination in any individual presenting with a seemingly benign back pain following a remote isolated episode of seizure, even in the absence of overt trauma. A detailed radiological evaluation guided by a meticulous history taking and detailed clinical examination is essential to rule out a fracture unless proven otherwise. It also shows that a single convulsive seizure can result in a potentially unstable fracture that when neglected, can result in devastating complications like spinal deformity and neurodeficit.

Level of evidence

Level IV.

1. Introduction

Non-traumatic spinal fractures occurring solely because of the violent paraspinal muscle contractions produced during a convulsive episode are very rare.^1,2 The diagnosis is easily missed at initial presentation, leading to serious complications like neurodeficit or symptomatic spinal instability. A majority of seizure-induced non-traumatic spinal fractures occurred in individuals with seizure-provoking risk factors (known epileptics with recurrent seizures, brain tumors, drug overdose/withdrawal, metabolic disorders, or electrolyte imbalance) or in those with an increased susceptibility to fracture due to decreased BMD following prolonged anticonvulsant therapy.^{3, 4, 5, 6, 7} To our existing knowledge, there are no case reports of a delayed presentation of a seizure-induced non-traumatic spinal fracture, unrelated to a remote episode of a single convulsive seizure.

2. Case report

A 52-year-old otherwise healthy non-epileptic male, construction worker presented with complaints of unrelenting low back pain of four months duration, following the first episode of a witnessed GTCS (generalized tonic clonic seizure) which he sustained four months ago while sitting in a chair at his house. He also had progressive numbness and weakness in both the lower limbs for ten days. A detailed inquiry revealed no history of a significant traumatic event either during the convulsive episode or thereafter.

Clinical examination revealed tenderness over the D12, L1 spinous processes, with painful restriction of spine movements. A meticulous neurological examination revealed grade 3/5 power in both the lower limbs, sensory blunting below L1 dermatome, normal deep tendon reflexes and a down going plantar response. Perianal sensation and rectal tone were intact. A detailed radiologic evaluation with plain radiographs (including dynamic films) [Fig. 1], computed tomography (CT) scan and magnetic resonance imaging (MRI) revealed an unstable burst fracture of L1 vertebra with kyphotic deformity of the dorsolumbar junction [Fig. 2]. A neurological evaluation including MRI of the brain and EEG (electroencephalogram) revealed no organic cause for the seizure. A complete metabolic and hormonal profile revealed no seizure provoking risk factors.

Fig. 1.

Standing anteroposterior (A) and dynamic lateral (B, C) radiographs of the thoracolumbar spine showing an old L1 unstable burst fracture with kyphotic deformity at the thoracolumbar junction. (D) T2-weighted sagittal MRI of the thoracolumbar spine, showing an old L1 burst fracture with retropulsion of the posterosuperior fragment causing compression of the conus.

Fig. 2.

(A) Sagittal CT image of the thoracolumbar spine showing features (white arrow) of an old unstable burst fracture of L1 vertebra. Sagittal CT images at the level of the left (B) and right (C) facets of D12/L1, showing subluxing facets (white arrow heads), a sign of posterior ligamentous complex injury. Axial (D) and coronal (E) CT images showing features of an unstable burst fracture of L1 vertebra, with features of attempted auto-stabilization of the fracture.

The patient was treated surgically using posterior instrumented stabilization, neural decompression, deformity correction by posterior column shortening osteotomy done at the D12-L1 level and fusion of D12/L1 facets. Patient was started on antiseizure medication and kept on regular follow-up. Patient showed significant improvement in VAS (Visual Analogue Scale) scores for back pain and good correction of kyphosis in the early postoperative period. There was complete neurological recovery with return to work at 3 months post-surgery. At 28-months follow-up, the patient had excellent functional outcomes and the radiographs showed no progression of deformity with good spinal alignment [Fig. 3].

Fig. 3.

Standing anteroposterior (A) and lateral (B) radiographs of the thoracolumbar spine taken at 26-months post-surgery, showing good healing of the L1 vertebral fracture, good correction of kyphosis and no loss of correction at 26-months follow-up.

3. Discussion

The incidence of spinal fractures in seizures varies from 0.95% to 16%.⁸ These fractures occur commonly due to a significant traumatic event during the seizure episode. However, a non-traumatic vertebral fracture occurring as a sole consequence of the violent muscle forces generated during a convulsive seizure is a rare clinical entity. Published literature shows that they commonly occur in individuals with risk factors (known epileptics with recurrent seizures, brain tumors, drug overdose, metabolic disorders, or electrolyte imbalance) which triggered the convulsive episode or in those with decreased BMD (due to anticonvulsant therapy or other medications) with an increased susceptibility to spine fracture.^{3, 4, 5, 6, 7} Individuals with increased muscle mass, decreased BMD, prolonged convulsions and recurrent convulsions are at high risk of post-ictal spinal fractures.⁸ Our case demonstrates the rare occurrence of a non-traumatic vertebral fracture during the first episode of a GTCS in a healthy non-epileptic individual with normal BMD and no seizure-provoking risk factors. Hence the fracture was the sole result of seizure-induced violent muscle contractions alone.

The violent contractions of the posterior paraspinal, and abdominopelvic musculature during a convulsive seizure can hyperflex the spine, which is then subjected to axial loading and flexion compressive forces directed along the anterior and middle spinal columns resulting in compression or burst fractures.^{5, 6, 7} These fractures are common in mid-thoracic spine (T3-T8) although fractures in lumbar spine have also been reported.^{3, 4, 5, 6,9,10}

Only 1% of these fractures are symptomatic and a serious spinal injury can be easily overseen due to the absence of overt external signs of trauma and the presence of post-ictal amnesia which fail to provide a clue for early diagnosis, and misinterpretation of motor weakness for post-ictal Todd’s paralysis.⁸ A high index of clinical suspicion combined with a meticulous musculoskeletal and neurological examination is imperative whenever a patient presents with back pain following a seizure.

Most seizure-induced spinal fractures are typically stable compression fractures without neurodeficit, although unstable burst fractures have been reported.^{4, 5, 6,8} The rarity of their occurrence, absence of an history or overt signs of a significant trauma and the common tendency to attribute a benign etiology to the back pain following a seizure often results in overlooking or under-investigating the spinal injury and failure to identify a potentially unstable fracture pattern which can present at a later date with devastating complications such as spinal deformity and late-onset neurological deficit. This emphasizes the need for a radiographic evaluation of the spine including dynamic lateral views (as guided by history and clinical examination) in a patient with complaint of back pain following a seizure. Additional assessment with MRI and CT to identify a potentially unstable fracture pattern (posterior osteoligamentous complex failure or a subluxating facet), [Fig. 2], is helpful to decide the modality of treatment.

Since its first report by Lehndorf in 1907, a few case reports of seizure-induced non-traumatic spinal fractures have been published in literature. In none of the previously published reports has the patient presented remotely, several months after the convulsive episode, which makes the diagnosis even more challenging. This is the first case report of a delayed unrelated presentation of a non-traumatic lumbar vertebral fracture with complications (spinal deformity and neurodeficit) consequent to a remote episode of a single convulsive seizure.

Institutional review board (IRB) approval

The study was approved by the IRB and Ethics committee of Madras Medical College, Chennai, India.

Source of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

CRediT authorship contribution statement

Aju Bosco: Conceptualization, Methodology, Formal analysis, Writing - original draft, Writing - review & editing, Software. Nalli Ramanathan Uvaraj: Conceptualization, Writing - review & editing, Visualization, Supervision. Eswar Ramakrishnan: Writing - original draft, Writing - review & editing, Software, Formal analysis.

Declaration of competing interest

The authors have no potential conflicts of interest.