|Ahead of print publication
A rare case of isolated congenital foot drop in a new-born infant
Narmadha Morvil1, Suresh Chandran2, Ashwani Bhatia1, Krishna Revanna Gopagondanahalli1
1 Department of Neonatology, KK Women's and Children's Hospital, Singapore
2 Department of Neonatology, Duke-NUS Medical School, Yong Loo Lin School of Medicine, Lee Kong Chian School of Medicine, Singapore
|Date of Submission||08-May-2020|
|Date of Decision||07-Aug-2020|
|Date of Acceptance||07-Aug-2020|
Krishna Revanna Gopagondanahalli,
Department of Neonatology, KK Women's and Children's Hospital, 100 Bukit Timah Road
Source of Support: None, Conflict of Interest: None
We report a case of congenital foot drop in a term neonate born through cesarean section for breech presentation. The antenatal history was unremarkable; the baby was born well and no significant anomalies were noted at birth except for right congenital foot drop. The rest of the neurological examination was unremarkable with normal head and spine ultrasound scans. The postnatal period was otherwise unremarkable with normal feeding and examination. Baby was discharged home in stable condition with regular physiotherapy on follow-up. The foot drop completely resolved by 3 months of age with physiotherapy alone. Baby is currently doing well with normal growth and development.
Keywords: Common peroneal nerve injury, congenital foot drop, congenital talipes equinovarus
|How to cite this URL:|
Morvil N, Chandran S, Bhatia A, Gopagondanahalli KR. A rare case of isolated congenital foot drop in a new-born infant. Med J DY Patil Vidyapeeth [Epub ahead of print] [cited 2021 Jun 13]. Available from: https://www.mjdrdypv.org/preprintarticle.asp?id=316407
| Introduction|| |
Foot drop is defined as the inability to dorsiflex the forefoot due to weakness of the muscles of the anterior compartment of the foot. This could be a result of either weakness of the muscles involved in the dorsiflexion of the foot or damage to the common fibular nerve supplying the muscles of the anterior compartment of the foot. The congenital foot drop in a new-born is rare and is often associated with an underlying neurological, muscular, or anatomical problem (structural talipes equinovarus deformity). The most common underlying lesions leading to common peroneal neuropraxia or any other mononeuropathies may be related to obstetric complications like birth trauma, foetal malpositioning such as breech presentation or transverse lie. We present a case of isolated congenital foot drop in an otherwise well neonate most likely due to common peroneal nerve injury which recovered well with regular physiotherapy.
| Case Report|| |
A routine postnatal screening examination of term male infant revealed a surprising right foot drop. He was born at 39 weeks of gestation by cesarean section for flexed breech. The antenatal period was unremarkable with normal screening and growth scans. Baby was vigorous at birth with Apgar scores of 9 at the 1st and 5th min of life, the birth weight was 3206 g. Examination of foot revealed inversion, plantar flexion at ankle with no active dorsiflexion, and minimal movement at the toes on stimulus (Babinski reflex) [Figure 1]. There was no wasting of muscles of the leg, and no bony/anatomical deformity was noted. The range of motion at the ankle was comparable. The active/passive movements were normal over other joints such as knee and hip joints and symmetrical when compared to the unaffected side. The sensation was grossly intact with evidence of withdrawal to touch. The rest of neurological examination was unremarkable with normal deep-tendon reflexes on both lower limbs. There were no dysmorphic features to note. The minor abnormalities noted were bilateral postural talipes equinovarus and mild left torticollis. The lower limb X-ray did not show any bony abnormality. The cranium and spine ultrasounds were normal. Brain magnetic resonance imaging was not done as the baby was clinically well with no other features suggestive of an upper motor neuron lesion. A diagnosis of congenital foot drop was made, and neurology consult was obtained which also concurred with the diagnosis of isolated congenital foot drop probably due to common peroneal nerve injury.
The baby was managed conservatively with physiotherapy and a resting splint for the affected foot to avoid contractures. He was discharged home in stable condition with scheduled follow-up. On follow-up, the foot drop gradually improved and was completely resolved by 3 months of age with normal developmental milestones and growth parameters [Figure 2].
|Figure 2: Both foots demonstrating positive Babinski reflex at 6 months of age|
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| Discussion|| |
Mononeuropathies in the neonatal population are very rare and most often due to trauma during birth process or compression in utero. The most common peripheral nerve injuries described in new-born are those involving the brachial plexus and facial nerve. Congenital foot drop due to peroneal nerve injury is an uncommon entity in the new-born period, most commonly reflects an abnormality due to a lower motor neuron lesion involving common peroneal nerve, sciatic nerve and rarely an upper motor neuron lesion involving the spinal cord or the motor cortex of the brain. It can also be due to structural defects of periarticular bones and the ligaments.
The isolated congenital foot drop in a new-born secondary to common peroneal nerve palsy is so rare that there are only two case reports and one case series with 50 cases of neonatal foot drop.,,
Foot drop in neonatal population is most likely due to compression, trauma, or entrapment of common peroneal nerve secondary to constriction bands., Other uncommon etiologies reported are ischemic necrosis of the gluteal region affecting the sciatic nerve following umbilical artery catheterization and Group B streptococcus osteomyelitis, but in these scenarios, the foot drop was not an isolated finding but had other localizing signs.,
Investigations in a case of foot drop should be directed by the clinical findings to rule out structural causes involving bones, nerves, and tendons surrounding the ankle joint. The brain and spine imaging may be considered if clinically indicated. The most important investigation to consider is nerve conduction studies (NCS) and electromyography (EMG). However, in a neonatal population, one must consider gestation-dependent motor nerve conduction velocity influencing the interpretation. It is also technically challenging to conduct a NCS in neonates due to limited tolerance for discomfort and sedation may be required to obtain meaningful data. In our case, we did not conduct a NCS or EMG, but we postulate that the peroneal nerve palsy is likely secondary to in utero compression given the breech presentation as well as evidence of other clues such as postural talipes equinovarus and left torticollis.
The congenital foot drop associated with congenital talipes equinovarus (CTEV) deformity secondary to common peroneal nerve injury is rare. Moreover, the foot drop may even be completely overlooked when associated with clubfoot due to similar appearance. Common peroneal nerve injuries, often occur where the nerve winds around the fibular neck as it is most susceptible susceptible to trauma, entrapment, and compression at this point. These cases are challenging to treat and are associated with the poor prognosis. The isolated peroneal nerve palsies caused by pressure or compression at the fibular head have a good prognosis but with concomitant CTEV deformity, one must also be wary of potentially worsening the common peroneal nerve palsy as a result of repeated cast pressure for CTEV treatment. Whether just a positional varus deformity of foot leads to common peroneal nerve injury resulting in foot drop is unclear.
The outcome of the congenital foot drop depends on the underlying etiology, but early physiotherapy and occupational therapy should be initiated to improve long-term outcomes. In a large case series with 50 cases of neonatal foot drop by Huaizy and Baban, all were conservatively managed with either immobilization by a back slab of the affected limb or physiotherapy. Recovery was noted to be faster when physiotherapy was implied. Timely surgical management was more relevant in cases of acquired nerve entrapment secondary to tumors in the pediatric population or in the event of concomitant complex clubfoot refractory to conservative management requiring Achilles tenotomy. The patients with congenital clubfoot and concomitant peroneal nerve dysfunction were resistant to conservative management and had unsatisfactory outcomes despite surgical release. However, if the peroneal nerve dysfunction was acquired as a result of repeated casting, they were noted to respond better with conservative treatment alone and resolve with time. In our case, there was significant improvement and complete resolution with conservative management suggesting that the peroneal nerve injury was likely neuropraxia.
An isolated uncomplicated congenital foot drop in neonates is extremely rare and intriguing. When encountered with this entity, a thorough family history and clinical examination is warranted. The investigations should be directed by clinical condition with early institution of physiotherapy and close monitoring for the recovery. The multidisciplinary care involving pediatric neurologist and orthopedic surgeons depend on underlying cause. Most of the isolated neonatal congenital foot drop has an excellent prognosis following physiotherapy.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]