Dorsal root entry zone lesioning for brachial plexus avulsion - technical evolution and long-term follow-up.

BACKGROUND: Brachial plexus avulsion (BPA) injuries can cause severe deafferentation pain. This has been successfully treated with dorsal root entry zone (DREZ) lesioning. Distortions in anatomy following a BPA injury can make identifying neural structures challenging. We describe a modification to the operative technique that improves the surgical view and the advanced intraoperative neuromonitoring (IONM) employed to identify DREZ. We have analysed the long-term outcomes for pain, quality of life, and complications in patients undergoing DREZ lesioning. METHODS: This is a single-centre retrospective case series including patients who underwent DREZ lesioning with IONM for brachial plexus avulsion between 2012 and 2022. Analysed data included pre- and postoperative pain (VAS), quality of life score for chronic pain, and complications. The evolution of the surgical approach is discussed. RESULTS: 44 consecutive patients underwent a DREZ lesioning procedure with intraoperative monitoring and mapping. In these patients the mean VAS score improved from 8.9 (7-10) to 1.87 (0-6) (p < 0.0001) at the time of discharge. 31 patients were followed-up for more than 12 months with a mean duration of follow-up of 41 months and their results were as follows: the mean VAS improved from 9.0 (7-10) to 4.1 (0-9) (p < 0.0001) at the last follow-up and the mean QOL values improved from 3.7 (2-6) to 7.4 (4-10) (p < 0.0001). The long-term outcomes were 'good' in 39%, 'fair' in 29% and 'poor' in 32% of patients. 55% of the patients were able to stop or reduce pain medications. CONCLUSIONS: Modifications of surgical technique provide better exposure of DREZ, and IONM aids in identifying DREZ in the presence of severe intra-dural changes. Long-term outcomes of DREZ lesioning indicate not only a reduction in pain but also a significant improvement in quality of life.

Anatomical damages in the spinal nerve roots and the spinal cord after brachial plexus injury: descriptive study from a cohort of consecutive patients who underwent DREZ-lesioning for pain-practical implications.

BACKGROUND: Systematic descriptions of anatomical damage after brachial plexus injury (BPI) at the intradural level have been scarcely reported in detail. However, considering these damages, not only in the spinal nerve roots but also in the spinal cord itself, is crucial in determining the appropriate surgical approach to restore upper limb function and address refractory pain. Therefore, the authors present a descriptive study focusing on intradural findings observed during microsurgical DREZ-lesioning. METHODS: This study enrolled 19 consecutive patients under the same protocol. Microsurgical observation through exposure of C4 to Th1 medullary segments allowed to describe the lesions in spinal nerve roots, meninges, and spinal cord. Electrical stimulation of the ventral roots checked the muscle responses. RESULTS: Extensive damage was observed among the 114 explored roots (six roots per patient), with only 21 (18.4%) ventral (VR) and 17 (14.9%) dorsal (DR) roots retaining all rootlets intact. Damage distribution varied, with the most frequent impairments in C6 VRs (18 patients) and the least in Th1 VRs (14 patients), while in all the 19 patients for the C6 DRs (the most frequently impaired) and in 14 patients for Th1 DRs (the less impaired). C4 roots were found damaged in 12 patients. Total or partial avulsions affected 63.3% and 69.8% of DRs and VRs, respectively, while 15.8% and 14.0% of the 114 DRs and VRs were atrophic, maintaining muscle responses to stimulation in half of those VRs. Pseudomeningoceles were present in 11 patients but absent in 46% of avulsed roots. Adhesive arachnoiditis was noted in 12 patients, and dorsal horn parenchymal alterations in 10. CONCLUSIONS: Knowledge of intradural lesions post-BPI helps in guiding surgical indications for repair and functional neurosurgery for pain control.

Optimizing donor fascicle selection in Oberlin's procedure: A retrospective review of anatomical variability using intraoperative neuromonitoring.

BACKGROUND: Transfer of the fascicle carrying the flexor carpi ulnaris (FCU) branch of the ulnar nerve (UN) to the biceps/brachialis muscle branch of the musculocutaneous nerve (Oberlin's procedure), is a mainstay technique for elbow flexion restoration in patients with upper brachial plexus injury. Despite its widespread use, there are few studies regarding the anatomic location of the donor fascicle for Oberlin's procedure. Our report aims to analyze the anatomical variability of this fascicle within the UN, while obtaining quantifiable, objective data with intraoperative neuromonitoring (IONM) for donor fascicle selection. METHODS: We performed a retrospective review of patients at our institution who underwent an Oberlin's procedure from September 2019 to July 2023. We used IONM for donor fascicle selection (greatest FCU muscle and least intrinsic hand muscle activation). We prospectively obtained demographic and electrophysiological data, as well as anatomical location of donor fascicles and post-surgical morbidities. Surgeon's perception of FCU/intrinsic muscle contraction was compared to objective muscle amplitude during IONM. RESULTS: Eight patients were included, with a mean age of 30.5 years and an injury-to-surgery interval of 4 months. Donor fascicle was located anterior in two cases, posterior in two, radial in two and ulnar in two patients. Correlation between surgeon's perception and IONM findings were consistent in six (75%) cases. No long term motor or sensory deficits were registered. CONCLUSIONS: Fascicle anatomy within the UN at the proximal arm is highly variable. The use of IONM can aid in optimizing donor fascicle selection for Oberlin's procedure.

Brachial plexus birth injuries: a multi-speciality approach. Commentary and opinions.

The management of brachial plexus birth injuries (BPBI) remains controversial and ever evolving. In this article, studies are examined to provide further insight into the ongoing controversies and debates surrounding BPBI. The articles are diverse and examine the topics of aetiology, demographics, reliability versus accuracy of measurements and surgical management. The management of BPBI may differ depending on resources. Outcome measures may also vary depending on geography. Future research should focus on developing consensus-validated measures and reproducible surgical techniques. These can then guide further population-based research and provide guidelines to minimize the incidence of BPBI.

3D SHINKEI MR neurography in evaluation of traumatic brachial plexus.

3D SHINKEI neurography is a new sequence for imaging the peripheral nerves. The study aims at assessing traumatic brachial plexus injury using this sequence. Fifty-eight patients with suspected trauma induced brachial plexus injury underwent MR neurography (MRN) imaging in 3D SHINKEI sequence at 3 T. Surgery and intraoperative somatosensory evoked potentials or clinical follow-up results were used as the reference standard. MRN, surgery and electromyography (EMG) findings were recorded at four levels of the brachial plexus-roots, trunks, cords and branches. Fifty-eight patients had pre- or postganglionic injury. The C5-C6 nerve postganglionic segment was the most common (average 42%) among the postganglionic injuries detected by 3D SHINKEI MRN. The diagnostic accuracy (83.75%) and the specificity (90.30%) of MRN higher than that of EMG (p < 0.001). There was no significant difference in the diagnostic sensitivity of MRN compared with EMG (p > 0.05). Eighteen patients with brachial plexus injury underwent surgical exploration after MRN examination and the correlation between MRN and surgery was 66.7%. Due to the high diagnostic accuracy and specificity, 3D SHINKEI MRN can comprehensively display the traumatic brachial plexus injury. This sequence has great potential in the accurate diagnosis of traumatic brachial plexus injury.

Peripheral nerve decompression for pain relief in the setting of previous obstetrical brachial plexus injury: a retrospective case series.

PURPOSE: In children with previous obstetrical brachial plexus injury (OBPI), upper extremity pain is present in 45 to 66% of patients. Recent literature reports this as musculoskeletal or neuropathic in nature. The purpose of the study is to demonstrate that peripheral nerve decompression, and neurolysis may be an effective treatment for patients with upper extremity pain in the context of previous OBPI. METHODS: A retrospective chart review was performed on patients undergoing peripheral nerve decompression and neurolysis after OBPI by senior author. The primary outcome assessed was pain, and secondary outcome measure was range of motion of the wrist and elbow. Outcome measures were assessed preoperatively as well as at their subsequent follow-up. RESULTS: Six patients were included, with a mean age of 14 years old at time of decompression. Three patients underwent median nerve, two patients underwent ulnar nerve, and one patient underwent posterior interosseous nerve decompression. There was a substantial improvement in pain post-operatively, demonstrated by reduction or resolution of subjective pain in all patients and resolution of Tinel's sign. There was a modest improvement in range of motion. CONCLUSION: This study demonstrates an improvement in subjective pain and range of motion after decompression and neurolysis in small subset of OBPI patients. It generates the hypothesis that peripheral nerve compression is a source of pain that can be addressed in this population. Future research should focus on confirming this hypothesis and assessing treatment options on a larger scale.

Validation of the Root Analysis Score for C5 Viability in Patients With Pan-Brachial Plexus Injury.

PURPOSE: Pan-brachial plexus injury patients present a reconstructive challenge. The root analysis score, developed from parsimonious multivariable modeling of 311 pan-brachial plexus injury patients, determines the probability of having a viable C5 nerve based on four categories: positive C5 Tinel test, intact C5 nerve on computed tomography myelogram, lack of hemidiaphragmatic elevation, and absence of midcervical paraspinal fibrillations. METHODS: Root analysis scores were calculated for a separate cohort of patients with pan-brachial plexus injuries. Scores were validated by the presence or absence of a graftable C5 root, based on supraclavicular exploration and intraoperative electrophysiologic testing. Receiver operating characteristic curve, accuracy, and concordance statistic of the scores were calculated. Patients were divided into three root analysis score cohorts: less than 50 (low), 50-75 (average), and 75-100 points (high) based on dividing the score into quartiles and combining the lowest two. The probability, sensitivity, and specificity of each cohort having an available C5 nerve were based on the intraoperative assessment. RESULTS: Eighty patients (mean age, 33.1 years; 15 women and 65 men) were included. Thirty-one patients (39%) had a viable C5 nerve. The root analysis calculator had an overall accuracy of 82.5%, a receiver operating characteristic of 0.87, and a concordance statistic of 0.87, demonstrating high overall predictive value; 6.5% of patients with a score of less than 50 (94% sensitivity and 43% specificity), 16.1% of patients with a score of 50-75 (94% sensitivity and 67% specificity), and 77.4% of patients with a score of 75-100 (77% sensitivity and 90% specificity) had a graftable C5 nerve. CONCLUSIONS: The root analysis score demonstrated high accuracy and predictive power for a viable C5 nerve. In patients with a score of less than 50, the necessity of supraclavicular root exploration should balance patient factors, presentation timing, and concomitant injuries. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnosis II.

[Nerve Transfers in Children with Non-traumatic Amyoplasia] / Nerventransfers bei Kindern mit nicht traumatischer AmyoplasieNerve Transfers in Children with Non-traumatic Amyoplasia.

BACKGROUND: The treatment of obstetric brachial plexus palsy through primary reconstruction and nerve transfers has been established in the past decades. In the case of non-traumatic diseases that lead to flaccid paralysis and the inability to move the extremities, such as transverse myelitis (TM) or arthrogryposis multiplex congenita (AMC), which can have a wide variety of causes, the focus has been on rehabilitative therapy so far, while surgical interventions have been used to a lesser extent, e. g., in the form of osteotomies or muscle transfers. Our aim is to establish nerve transfers as a surgical option to improve mobility in non-traumatic amyoplasia. PATIENTS: This work presents the needs-adapted treatment of a total of 23 patients (aged 4 months to 64 months, 18 with AMC and 5 with TM) using nerve transfers on the upper extremity. RESULTS: We were able to show that early nerve transfers in the upper extremity enabled the reanimation of muscles in both AMC and TM. CONCLUSION: This work shows that the treatment of non-traumatic amyoplasia in children with selective nerve grafts is a successful method. Nerve transfers allow patients to gain or regain important functions for managing independent everyday life. The surgical methods have been established in the treatment of traumatic nerve injuries. They are well-known and can be carried out safely. We believe that this is an important treatment option for paediatric patients with paralysis associated with TM or AMC, which should also be known to the treating physicians.

Functional Free Muscle Transfer for Reconstruction of Traumatic Adult Brachial Plexus Injuries.

Traumatic brachial plexus injury is the most common indication for functional free muscle transfer, and elbow flexion recovery is the functional target, followed by shoulder stability and hand reanimation. In this article, we provide a literature review of functional free muscle transfer (FFMT) for adult traumatic brachial plexus injuries and the surgical technical recommendations to achieve the best functional results with FFMT for adult traumatic brachial plexus injuries.

Retro Oesophageal Transfer of Contralateral C7 in Birth Brachial Plexus Injury - A Retrospective Study.

Background: Presence of available healthy nerve roots on the injured side determines the outcome after nerve reconstruction. Paucity of nerve roots warrants contralateral C7 harvest for optimal results. We aim to study the risks and benefits of retro oesophageal transfer of contralateral C7 root in infants with birth brachial plexus injury. Methods: Study was carried out from 2017 to 2022 in 13 children who have undergone retro oesophageal transfer of contralateral C7 root to affected side. Follow-up period ranged from 8 to 60 months after the surgery. Motor power assessment was done using by active movement scale. Results: Average active movement score for abduction was found to be 6, elbow flexion 5.7, elbow extension 5.8, wrist extension 3, wrist flexion 4, finger flexion 4.8 and finger extension 3.8, respectively. No neurological deficits, limb length anomaly noted in the normal upper limb after contralateral C7 harvest. Conclusions: Retro oesophageal transfer of contralateral C7 is a safe technique in birth brachial plexus injury. The advantage of retro oesophageal transfer is reduction in the length of nerve grafts, thus helping in early neurotisation of distal forearm and hand muscles. The large axonal output from contralateral C7 can be used to reconstruct different nerves without any residual deficits on the normal side. Level of Evidence: Level IV (Therapeutic).

Rehabilitation protocols in neonates undergoing primary nerve surgery for upper brachial plexus palsy: A scoping review.

INTRODUCTION: Surgical management is recommended in patients with severe neonatal brachial plexus palsy (NBPP) within the first 6 months of age to regain best possible function. Rehabilitation post-surgery remains relatively unexplored. This is a scoping review that explores, which rehabilitation modalities exist and how they vary for different microsurgical approaches in NBPP. MATERIALS AND METHODS: A systematic search was conducted to include articles about upper trunk obstetric brachial plexus nerve microsurgery in pediatric patients that made mention of rehabilitation protocols. The aims of rehabilitation modalities varied and were grouped: "passive" movement to prevent joint contracture or stiffness, "active" or task-oriented movement to improve motor function, or "providing initial motor recovery". Surgical approach was described as either exploration of the brachial plexus (EBP) or nerve transfer without root exploration (NTwoRE). Technique was categorized into transfers and non-transfers. RESULTS: Thirty-six full-text articles were included. Initiation of rehabilitation was 22.26 days post-surgery. Twenty-eight studies were EBP, and six were NTwoRE. Of studies classifiable by aims, nine were "passive", nine were "active", and five were "providing initial motor recovery". Only 27.7% of EBP studies mentioned active therapy, while 75.0% of NTwoRE studies mentioned active therapy. The average age of patients in the EBP procedure category was 7.70 months, and NTwoRE was 17.76 months. Within transfers, the spinal accessory to suprascapular group was more likely to describe an active shoulder exercise therapy, whereas contralateral C7 group was more likely to describe "initial motor recovery", especially through the use of electrostimulation. All articles on electrostimulation recommended 15-20-minute daily treatment. CONCLUSION: Information on rehabilitation is limited post-nerve surgery in NBPP. However, when mentioned, the aims of these therapies vary with respect to surgical approach and technique. The type of therapy to employ may be a multifaceted decision, involving factors such as patient age, initial deformity, and goals of the care team.

Intercostal nerve transfer in management of biceps and triceps co-contraction in brachial plexus birth palsy.

OBJECTIVE: Brachial plexus birth palsy (BPBP) is often caused by traction during birth. In some cases, reinnervation occurs during spontaneous recovery and it causes involuntary co-contraction between antagonistic muscles. When it comes up between the biceps and triceps muscles, smooth active motion of the elbow joint is impaired. We are presenting outcomes of intercostal nerve (ICN) to radial nerve transfer to minimize elbow motion abnormality due to co-contraction. METHODS: We present five cases (two males and three females) of biceps and triceps co-contraction in BPBP patients treated from 2005 to 2018. The mean age at surgery was 9.36 years (range, 4.8-16.4 years). They were treated by ICNs transfer to motor branch of the radial nerve to the triceps muscle. Preoperative electromyography was done in all cases to confirm biceps and triceps co-contraction and to assess the contractile status of both muscles. A 10-s flexion extension test was done pre and postoperatively to assess the efficacy of our procedure. RESULTS: The postop course was uneventful. No donor site morbidity or respiratory complications were recorded in any patient. The mean postoperative follow-up period was 83.9 months (range, 53.6-135.5 months). At the final follow-up, elbow flexion was M4 in the Medical Research Council (MRC) grading scale in all five patients and elbow extension was graded M4 or M4- in all five patients. There was significant increase in the 10 s flexion extension test results delineating the effectiveness of the procedure. CONCLUSIONS: ICNs transfer to motor branch of the radial nerve to the triceps muscle for management of biceps and triceps co-contraction in BPBP is a good option with minimal morbidity and good success rate.

Brachial plexus birth injury: advances and controversies.

While there is considerable spontaneous recovery in most cases of brachial plexus birth injury, many children are left with significant problems that may lead to lifelong functional limitations, loss of work and social isolation. Detailed treatment with the right strategy can provide very valuable improvement in function. Over the past few years, the clinical approach to brachial plexus birth palsy has entered a new era in both diagnostic and surgical treatment methods. This article reviews four areas of management, the role of imaging in defining the severity of the injury, the optimal timing of for nerve exploration and reconstruction in appropriate cases, the advantages and potential complications of nerve transfers, and the role of physiotherapy. Available evidence is considered. Although it is difficult to make clear and precise inferences on a subject where there are many variables and considerable uncertainties, some currently accepted views will be summarized.Level of evidence: V.

Adult traumatic brachial plexus injuries: advances and current updates.

Nerve grafting, tendon transfer and joint fusion are routinely used to improve the upper limb function in patients with brachial plexus palsies. Newer techniques have been developed that provide additional options for reconstruction. Nerve transfer is a tool for restoring upper limb function in total root avulsions where nerve grafting is not possible. In partial brachial plexus injuries, nerve transfers can greatly improve shoulder, elbow, wrist and hand function. Intraoperative electrical stimulation can be used to diagnose precisely which nerve is injured and to choose which nerve fascicles should be transferred. Finally, measuring the postoperative outcome can improve the evaluation of our techniques. The aim of this article was to present the current techniques used to treat patients with brachial plexus injury.

Advancing glenohumeral dysplasia treatment in brachial plexus birth injury: the end-to-side spinal accessory to suprascapular nerve transfer technique.

PURPOSE: Brachial plexus birth injury (BPBI) is a common injury with the spectrum of disease prognosis ranging from spontaneous recovery to lifelong debilitating disability. A common sequela of BPBI is glenohumeral dysplasia (GHD) which, if not addressed early on, can lead to shoulder dysfunction as the child matures. However, there are no clear criteria for when to employ various surgical procedures for the correction of GHD. METHODS: We describe our approach to correcting GDH in infants with BPBIs using a reverse end-to-side (ETS) transfer from the spinal accessory to the suprascapular nerve. This technique is employed in infants that present with GHD with poor external rotation (ER) function who would not necessitate a complete end-to-end transfer and are still too young for a tendon transfer. In this study, we present our outcomes in seven patients. RESULTS: At presentation, all patients had persistent weakness of the upper trunk and functional limitations of the shoulder. Point-of-care ultrasounds confirmed GHD in each case. Five patients were male, and two patients were female, with a mean age of 3.3 months age (4 days-7 months) at presentation. Surgery was performed on average at 5.8 months of age (3-8.6 months). All seven patients treated with a reverse ETS approach had full recovery of ER according to active movement scores at the latest follow-up. Additionally, ultrasounds at the latest follow-up showed a complete resolution of GHD. CONCLUSION: In infants with BPBI and evidence of GHD with poor ER, end-to-end nerve transfers, which initially downgrade function, or tendon transfers, that are not age-appropriate for the patient, are not recommended. Instead, we report seven successful cases of infants who underwent ETS spinal accessory to suprascapular nerve transfer for the treatment of GHD following BPBI.

[Contralateral C7 Nerve Transfer]. / Der kontralaterale C7 Transfer.

Complex brachial plexus injuries with multiple or complete root avulsions make intraplexic reconstruction impossible in some cases. Such cases necessitate the use of extraplexic nerve donors such as the spinal accessory nerve or intercostal nerves. The contralateral C7 root represents a donor with a high axon count and can be used as an axon source in such cases. We summarise current indications, surgical technique and functional results after a contralateral C7 transfer in cases of brachial plexus injury, describing some of our own cases and including a selective literature review.

C5 nerve root palsy (without prior cervical decompression) case series: 9 patients with critical delay to presentation.

BACKGROUND: Distinguishing between cervical nerve root and intrinsic shoulder pathology can be a difficult task given the overlapping and often coexisting symptoms. OBJECTIVE: The objective of this study was to highlight the often-complicated presentation of these symptoms and the subsequent potential for delay in care regarding this subset of patients. METHODS: A total of 9 patients, managed by one of two different surgeons, were identified with a history of C5 nerve root palsy. A chart review was conducted, and the following information was recorded: presenting complaint, time from symptom onset to diagnosis, time from symptom onset to presentation to a spine surgeon, first specialist seen for symptoms, non-spinal advanced imaging and treatment conducted before diagnosis, preoperative and postoperative exam, time to recovery, and type of surgery. RESULTS: We observed an average time from onset of symptoms to presentation to a spine surgeon to be 31.6 weeks. These patients' time to full recovery after cervical decompression was 15 weeks. CONCLUSION: : We observed a critical delay to presentation in this series of patients with C5 nerve palsy. C5 nerve palsy should remain an elemental part of the differential diagnosis in the setting of any shoulder or neck pain presenting with weakness.

Hand function outcomes following surgical treatment of complete neonatal brachial plexus palsy.

PURPOSE: Although re-innervation of the hand is considered a priority in the treatment of infants with complete brachial plexus injury, there is currently a paucity of publications investigating hand function outcomes following primary nerve reconstruction in infants with neonatal brachial plexus palsy (NBPP). This study therefore aimed to evaluate hand function outcomes in a series of patients with complete NBPP. METHODS: This retrospective case series included all patients who underwent primary nerve surgery for complete neonatal brachial plexus palsy over an 8-year period. Outcomes were assessed using the Raimond Hand Scale. Classification of grade 3 or higher indicates a functional hand (assistance in bimanual activity). RESULTS: Nineteen patients with a complete NBPP underwent primary nerve reconstruction at a mean age of 3.7 months. Periodic clinical evaluations were performed until at least 4 years of age. According to the Raimondi hand scale, one patient did not recover (grade 0), three patients attained grade 1, four grade 2, ten grade 3, and in one grade 4. Overall hand functional recovery was achieved in 57.8% (11/19) of patients. CONCLUSION: Sufficient recovery of hand function to perform bimanual activity tasks in patients with complete NBPP lesions is possible and should be a priority in the surgical treatment of these infants.

Surgery for internal rotation contracture in infancy may obviate the need for brachial plexus nerve reconstruction: early experience.

BACKGROUND: Shoulder internal rotation contracture and subluxation in the first year of life has long been recognized in some patients with brachial plexus birth injury (BPBI). Surgical management of shoulder pathology has traditionally been undertaken following nerve reconstruction as necessary. In some patients; however, shoulder pathology may impair or obscure functional neuromuscular recovery of the upper extremity. As a proof of concept, we report a highly selected subset of patients with BPBI in whom shoulder surgery undertaken before one year of age obviated the need for neuroma resection and nerve grafting. METHODS: A retrospective review was performed of all patients with upper trunk BPBI who underwent shoulder surgery before one year of age from 2015 to 2018. Upper extremity motor function was evaluated with preoperative and postoperative Active Movement Scale scores, Cookie tests, and the requirement for subsequent neuroma resection and nerve grafting. RESULTS: Fifteen patients with BPBI meeting the inclusion criteria underwent shoulder surgery (including a subscapularis slide and tendon transfers of the teres major and latissimus dorsi muscles) before 1 year of age. Preoperatively, no patients of the appropriate age passed the Cookie test for elbow flexion. Thirteen patients either passed the Cookie test or scored Active Movement Scale score 7 for elbow flexion at or before the last available follow-up undertaken at a median age of 3.4 [1.4, 5.2] years. One of those 13 patients underwent single fascicular distal nerve transfer to improve elbow flexion before subsequently passing the Cookie test. Two patients did not have sufficient follow-up to assess elbow flexion. CONCLUSION: Although the exact role of shoulder surgery in infancy for BPBI remains to be defined, the findings from this study provide proof of concept that early, targeted surgical treatment of the shoulder may obviate the need for brachial plexus nerve reconstruction in a highly selected group of infants with BPBI.