Multilevel Laminectomy for Lumbar Spinal Stenosis With Low Back Pain in Achondroplasia: A Case Report

Introduction

Achondroplasia is the most common form of skeletal dysplasia and etiology of dwarfism, emerging from mutation in the fibroblast growth factor receptor 3 (FGFR3) gene, which inhibits endochondral bone formation [1,2]. It is inherited in an autosomal dominant pattern, although current estimates suggest that approximately 80% of the cases are caused by sporadic de novo mutations of the FGFR3 gene [1,2]. The reported incidence is around 1 per 16 000 to 25 000 live births [3]. Individuals with this condition typically have a long, narrow trunk; rhizomelic limb shortening; and macrocephaly with frontal bossing [1,3,4]. The impaired longitudinal growth results in early fusion of the pedicles to the vertebral bodies in the spine [4–6].

Lumbar spinal stenosis (LSS) in achondroplasia usually arises from a combination of congenital spinal dysplasia and degenerative changes [1]. The early fusion of the pedicles to the vertebral bodies along with the reduced interpedicular distance limits the available dural space and results in a narrow spinal canal [3]. Furthermore, as these individuals age, hypertrophy of ligamentous and bony structures, disc degeneration, and facet joint changes further compromise the already limited diameter of the spinal canal [3]. Because of the structural severity and multilevel involvement, conservative management of these patients often fails [1,3,4]. As a result, surgical decompression becomes an important way to relieve symptoms and prevent further neurological decline [4,5].

This report describes the case of a 55-year-old woman with achondroplastic dwarfism and a history of back pain due to spinal stenosis, managed with a multilevel laminectomy. She had rapid postoperative recovery of neurologic deficit after multilevel posterior decompression surgery, despite prolonged symptom history, which shows the potential benefit of surgery even in cases with chronic debilitating symptoms. We provide a summary of spinal decompression techniques in achondroplasia, particularly intraoperative considerations and reported outcomes, discussing the surgical challenges in management of these cases.

Case Report

PRESENTATION AND HISTORY:

A 55-year-old woman with achondroplasia presented to an outpatient clinic with a 5-year history of progressively worsening low back pain and lower-limb weakness. For the past 2 years, she was unable to sleep in a supine position due to discomfort and pain. She had bilateral sensory problems, with numbness along the posterior thighs and anterior aspects of both lower legs. She also had neurogenic claudication in both legs, experiencing pain after walking just 20 meters.

EXAMINATION AND DIAGNOSIS:

The diagnosis of achondroplasia in this patient was established clinically based on characteristic phenotypic features, including short stature, rhizomelic limb shortening, and frontal bossing, and was genetically confirmed in early adulthood as an autosomal dominant FGFR3 mutation.

Clinical examination revealed gait disturbance with bilateral foot drop, gradually developing during the last 5 years. The anterior tibialis strength was graded 2/5 on the right and 3/5 on the left according to the Medical Research Council (MRC) scale. In addition, muscle strength of right lower-limb quadriceps was also reduced, graded 2/5 on the MRC scale, in conjunction with diminished patellar reflexes bilaterally, which was 1+ according to the deep tendon reflex (DTR) scale. Sensory examination indicated the presence of hypoesthesia in the right lower limb of L3–L5 dermatomal distribution. Magnetic resonance imaging (MRI) revealed severe spinal stenosis at L2–L3, L3–L4, and L4–L5. Preoperative MRI evaluation is presented in Figure 1.

The presence of bilateral foot drop, significant motor deficits, and neurogenic claudication necessitated surgical management to prevent further neurological deterioration and to restore functional mobility. Unfortunately, data on preoperative progression of the neurologic deficit were incomplete. Surgery was initially postponed due to the complexity of the spinal anatomy and multilevel stenosis. However, after meticulous evaluation at our center and thorough discussion of potential risks and potential benefits of surgery, patient consent was given.

SURGICAL MANAGEMENT:

Initially, the patient was placed prone under general anesthesia on a radiolucent operating table. As routinely conducted, bolsters were used for support of the chest and pelvis, eliminating abdominal pressure to facilitate venous return. The hips and knees were flexed to maximize interlaminar space dimensions and facilitate decompressions. Due to the skeletal features of this patient, this maneuver was of utmost surgical importance. Subsequently, an incision was planned to include levels of interest under fluoroscopic navigation.

A routine posterior approach was then implemented with skin incision, dissection of subcutaneous fat, and meticulous subperiosteal detachment of paravertebral musculature with dissection of L3–L5 laminae bilaterally (Figure 2). The patient underwent laminectomy and neural decompression at the L2–L3, L3–L4, and L4–L5 levels, with subsequent routine wound closure in layers.

POSTOPERATIVE OUTCOME AND FOLLOW-UP:

The patient’s condition improved immediately after the procedure. Mobilization was achieved in 3 hours following the procedure and she was discharged on the same day without any perioperative complications, being advised to walk using a lumbar orthosis and to avoid spinal flexion, extension, lateral bending, and rotation, avoiding weight bearing, and with progressive resumption of her daily routine. At 1-, 2-, and 4-week follow-up visits, she reported an improvement in symptoms and finally could sleep lying flat for the first time in 2 years. Gait and lower-limb strength improved, and overall functional mobility was restored. Furthermore, she was able to walk over 200 meters without experiencing neurogenic claudication. At the final follow-up, the anterior tibialis was graded 4/5 bilaterally and quadriceps strength on the right was also graded 4/5 according to the MRC scale. Patellar reflexes were also restored to 2+, and sensation in the lower limbs had improved on examination. These results were accomplished via an intensive physical therapy program implemented after the first postoperative week, primarily focusing on active muscular strengthening, proprioception, and neural tissue mobilization exercises. She expressed satisfaction with her functional improvement and reported marked relief of pain. Figure 3 shows the patient demonstrating dorsiflexion of the toes, reflecting the recovery of distal motor function postoperatively.

Discussion

This case report illustrates that significant neurological recovery can occur in achondroplasia-associated LSS even after years of progressive symptoms, but only when surgical decompression and perioperative management are meticulously applied. Although many medical complications that are encountered in patients with achondroplasia can cause developmental deformities, LSS is an increasingly common condition in these patients, associated with reduced quality of life [4]. The combination of shortened pedicles, reduced interpedicular space, and thickened laminae ultimately narrows the spinal canal, which can lead to nerve root compression and symptomatic spinal stenosis [1,4–6]. Clinically, these patients present with low back pain, neurogenic claudication, limb weakness with functional mobility, and, in more severe cases, bladder and bowel dysfunction due to parasympathetic fibers dysregulation [3,4]. About 40% of adults with achondroplasia develop chronic back ailments and half of them undergo spinal surgery [3,7]. Anatomical features in achondroplasia patients in conjunction with surgical relevance and practical points from a surgical view are presented in Table 1 [4,7–13]. Although the anatomical challenges of achondroplasia have been documented, the true challenge lies in correlation of these characteristics with intraoperative complications. Hence, meticulous preoperative planning with recognition of these characteristics and potential risks is crucial for successful surgery.

Patil et al recently studied over 200 patients with achondroplasia undergoing laminectomy and compared them to the general population [14], showing that patients with achondroplasia are at an increased risk of 90-day postoperative surgical complications and often need more careful postoperative monitoring [14]. Chintapalli and Desai [15] found higher risk of postoperative complication in achondroplasia patients subjected to multiple spine decompression procedures compared with matched controls [15].

Hariharan et al noted revision surgery rates as high as 38% in achondroplasia patients, primarily due to pseudarthrosis from previously attempted spinal fusions, proximal junctional kyphosis, and, most importantly, poor decompression [16]. The present case highlights the importance of preoperative planning to prevent complications such as those discussed above. A deep understanding of the anatomical features associated with achondroplasia and appropriate selection of the surgical approach are essential to achieve optimal outcomes, as demonstrated in this report.

Carlisle et al demonstrated that a surgical decompression procedure within 6 months of symptom onset was associated with good functional results [8]. While earlier decompression is obviously ideal, our findings suggest that chronic symptoms do not always predict poor outcomes. The patient in this case had a 5-year history of worsening symptoms, but the absence of bladder or bowel dysfunction and the stable neurological baseline likely contributed to a better recovery [8]. Furthermore, her past medical history was unremarkable for other disorders that can promote neural tissue damage (eg, diabetes mellitus, chronic kidney disease, and other neurologic disorders), which can also hinder improvement of neurologic deficits. These chronic, established motor deficits that can be associated with inability to walk should not be a relative contraindication for surgical management in these patients since, as in our case, decompression surgery can lead to rapid and significant amelioration of motor deficit and neurogenic claudication due to release of pressure on the dural sac and nerve roots, improving patient quality of life.

Several studies suggest that in achondroplasia patients, preservation of posterior tension band or posterior ligamentous complex during surgery is crucial as these patients are at higher risk of developing postoperative kyphosis [17–19]. Podkovik described a modified interapophysealaminar decompression technique that preserved the posterior tension band [17]. Ain et al reported that instrumented fusion is also recommended in cases with extensive decompression to prevent postoperative kyphosis [9].

Additionally, the reported high revision rates following spinal decompression in achondroplasia patients could make surgeons consider early fusion surgery [4,9,10,16,20]. However, in the present case, we decided to perform a multilevel laminectomy without instrumentation, aiming to preserve the posterior ligamentous complex. Because of her older age, we decided not to proceed with fusion to avoid early and late spinal fusion complications such as hemorrhage, wound complications, implant failure, adjacent segment disease, proximal junctional kyphosis, and pseudarthrosis, which may all necessitate revision surgery in these vulnerable individuals [16]. In this context, other minimally invasive procedures for postoperative iatrogenic instability avoidance in surgical management of LSS as unilateral laminotomy for bilateral decompression should be meticulously considered, since they may increase wound complications rates due to the longer surgery necessitated by the disturbed physiologic anatomy in these patients [21]. Table 2 provides a comparative practical overview of the previously mentioned surgical approaches, including instrumented fusion, discussing advantages and disadvantages of each procedure, selection of which should be conducted on a case-by-case basis considering clinical and imaging characteristics, age, comorbidities and functional status [1,5,8,9,14,18,19,21,22].

Multiple studies have evaluated the role of laminectomy in the surgical management of LSS in patients with achondroplasia. Ain et al reported favorable outcomes in a cohort of 48 patients, even though the procedures were associated with a 15% incidence of dural tears and risk of postoperative kyphosis [9]. Hallan et al and Agabegi et al [18,19] reported similar findings, in which patients developed post-laminectomy kyphosis requiring secondary intervention [9,18,19]. This is why fusion is often considered in multilevel decompressions, especially in the presence of instability or sagittal imbalance. Additionally, surgical experience is required to successfully deal with the altered anatomy and narrow safety margins in patients with achondroplasia. The surgeon needs to be familiar with the dysplastic pedicle trajectories, dural adhesions, and spinal alignment anomalies to optimize clinical outcomes. Moreover, optimization of clinical outcomes is affected by the entire perioperative management of these patients. Parameters that have not been standardized yet for meticulous preoperative evaluation, postoperative management in terms of pharmacologic and non-pharmacologic measures, and gradual return to daily routine, depending on chronicity of symptoms [23]. In line with these considerations, Fu et al [24] presented a case series of 9 adults with achondroplasia who developed complicated lumbar spinal stenosis and associated spinal deformities, managed through various combinations of decompression and fusion procedures [24]. Their report emphasized that surgical planning should be individualized according to anatomical severity and deformity pattern. Comparable to their findings, our case demonstrates that multilevel decompression without fusion can yield favorable neurological recovery when sagittal alignment and segmental stability are preserved.

Our case demonstrates that laminectomy without fusion can be safely performed in patients with neutral alignment, no clinical signs of instability, and well-documented neurologic deficits in correlation with imaging findings, even in patients with multilevel stenosis. The literature supports laminectomy as a viable technique, but patient selection, preservation of posterior elements, and postoperative monitoring remain important to minimize complications and improve outcomes. Furthermore, chronicity of symptomatology, even in cases with motor deficit, should not preclude the decision for surgical management.

Conclusions

Dural tear is one of the most common and concerning complications in achondroplasia-related spine surgeries. Shortened pedicles and a shallow spinal canal significantly narrow the working corridor, increasing the risk of unintentional dural injuries. In this context, routine use of intraoperative fluoroscopy (C-arm) to correctly assess the depth of the spinal canal is strongly recommended during all steps of surgery. In addition, the use of microsurgical techniques under high magnification to safely detach the dura and to mobilize nerve roots is essential to minimize complications. Combining these 2 important intraoperative elements – accurate removal of bony elements and safety during nerve decompression – can help surgeons deal with the altered anatomy of these patients. Moreover, chronic and established neurologic deficits should not exclude these patients from surgical management, since it can significantly contribute to functional improvement in the context of underlying disease.