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Citation: Ghanmi M, Gaddour M, Toulgui E, Ouanes W, Jemni S. Neurogenic heterotopic ossification causing sciatic nerve entrapment in Children:

A case report. Ghanmi et al © All rights are reserved. https://doi.org/10.32512/jmr.4.2.2021/10.12

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Case Report

Ghanmi Marwa

**1

, Gaddour Mariem

, Toulgui Emna

, Ouanes Walid

, Jemni Sonia

Neurogenic heterotopic ossification causing sciatic nerve entrapment in children: A case report.

1: Faculty of Medicine, Monastir,

Tunisia.

2: Physical medicine and rehabilitation

department, Sahloul University Hospital

Sousse, Tunisia.

* Corresponding author

** Academic Editor

Correspondence to:

gadmariem@gmail.com

Publication Data:

Submitted: February 22,2022

Accepted: April 18,2022

Online: June 30,2022

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Heterotopic ossification (HO) is an abnormal formation of mature lamellar bone in soft tissues. It is

usually containing bone marrow. Neurogenic HO is rare in pediatric practice and occurs after insult

to the nervous system. We herein present one of the first reports of sciatic nerve entrapment

caused by neurogenic HO in a 4-year-old boy presenting with severe traumatic brain injury. The

aim was to highlight clinical and radiological characteristics and to discuss the most accurate

diagnostic tools.

Keywords

heterotopic ossification; children, sciatic nerve; entrapment.

Introduction

Neurogenic HO is seen after central and less frequently peripheral nervous system insults,

including spinal trauma and traumatic brain injuries (TBI). The pathogenesis may depend on

the transformation of mesenchymal to bone-forming cells in response to a variety of stimuli.

Reports suggest that stimuli may be due to immobilization, muscles microtrauma, spasticity

of special muscle groups, disturbance of the protein and electrolyte balance, alteration of

vasomotor outflow, and tissue hypoxia [1,2].

The prevalence of HO after spinal cord injuries is estimated at 20-25% and following

traumatic brain injury (TBI) at 10-23% (5) in adult population. It is less frequent among

children, estimated at 10% after spinal cord injury (SCI) and TBI [3]. This entity remained

almost unreported in children and might be the misdiagnosed cause of handicap in several

cases.

Observation

A 4-yr-old boy presented with severe TBI after a domestic accident. Initial management was

marked by long coma and several neurosurgical procedures. He was admitted to the

rehabilitation unit five months after the accident. He had cranial fracture and cerebral

contusion complicated with infection, diffuse axonal injury and cerebellar contusion. On

admission the patient was aphasic. He had spastic flexion deformities in upper limbs and

spastic extension deformities in lower limbs. Elbow, hip, knee and ankle joint ranges of

motions were limited bilaterally. Substantial neurological examination could not be performed

because of joint limitations, but gross motor strengths were tested using medical research

council scale (MRC) revealing 2 on the right and 3 on the left side. He had action tremor and

static balance dysfunction. Functional independence measure for children (weeFIM) score

was 22, careful goniometric measurement of the hip showed bilateral limitation in flexion (60

on the right side and 80 on the left side), rotations were completely impossible on the right

side and severely limited on the left side. The patient showed signs of suffering upon

mobilization of the hip. Neurogenic HO was suspected. Standard radiography showed

bilateral islands of calcification around the hip Brooker grade 1 (figure 1). Alkaline

phosphatase in the blood serum were as high as 3 times the normal rate (348 U per liter).

Computed Tomography of the hips showed posterior ossification in the coxofemoral joints

consistent with mature neurogenic ossification surrounding the sciatic nerve on both sides

(figure 2,3). Electrodiagnostic evaluations were consistent with axonal degeneration of the

right sciatic nerve. The rest of the muscles, including the quadriceps, gluteus Maximus,

gluteus mediums, and lumbar paravertebral muscles, were normal. Rehabilitation program

was carried on with intensive range-of-motion exercises for the elbow, hip, knee, and ankle

joints. Paracetamol was used for pain treatment. He was not proposed for a surgical

treatment, because the sciatic nerve entrapment was not responsible for the spastic gait

disorder. we decided to start with botulinum toxin injection to the gastrocnemius, soleus and

popliteus to straighten the leg and the foot.

Abstract

Neurogenic heterotopic ossification causing sciatic nerve entrapment in Children: a case report

Citation: Ghanmi M, Gaddour M, Toulgui E, Ouanes W, Jemni S. Neurogenic heterotopic ossification causing sciatic nerve entrapment in Children:

Figure 1: plain radiography showing bilateral islands of calcification around the hip

(Brooker grade 1).

Figure 2,3: CT scan of the hips showing posterior heterotopic ossification causing compression to the sciatic nerve.

Discussion

Heterotopic ossification (HO) is defined as the extraskeletal bone formation in soft tissues, blood vessels, ligaments and

muscles. The pathogenesis is still unclear and involves multiple complex inflammatory cascades mediated by different

neuroinflammatory substances. Three types of HO have been described: traumatic, neurogenic and hereditary [4]. The

disease always appears caudally to the lesion level, mainly in the hip, knee, elbow and shoulder joints. The hip is the most

affected joint in children [5]. A sciatic nerve lesion secondary to heterotopic ossification compression is rare even in adult

population. Release of the entrapped sciatic nerve may restore functions partially or completely. However, disabilities are

frequently permanent due to late diagnosis, autonomic dysreflexia and muscle spasticity. An early electrophysiologic study

maybe useful to determine the location and severity of nerve damage in severe SCI and TBI cases [6]. Prevention of HO for

high‐risk injury patterns may reduce the morbidity rate and enhance the functional prognosis. Susceptibility for HO formation is

a diverse process with several leading factors still to be defined. Steroidal and non-steroidal anti-inflammatory as well as

bisphosphonate and radiation therapy are routinely used to modulate inflammation in high-risk patients. Once established, only

surgical excision of HO neoformations with releasee of nervous adjacent structures can ensure functional improvement [7].

Neurogenic heterotopic ossification causing sciatic nerve entrapment in Children: a case report

Citation: Ghanmi M, Gaddour M, Toulgui E, Ouanes W, Jemni S. Neurogenic heterotopic ossification causing sciatic nerve entrapment in Children:

Conflict of Interest: None

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