Physical Therapy for a Patient With Alternating Hemiplegia of Childhood: A Case Report

Abstract

Purpose: 

Alternating hemiplegia of childhood (AHC) is a rare neurological disorder that can influence posture and movement during critical periods of motor development. There are no descriptions of physical therapy for children with AHC. The purpose of this case report is to present an example of physical therapy evaluation, intervention, and outcomes for a child with AHC.

Summary of Key Points: 

Physical therapy services were provided over 9 sequential plans of care between 14 and 52 months of age. The child demonstrated improvements in motor control, walked independently at 16.5 months of age, and her Gross Motor Function Measure-88 score increased from 78% to 95% between 27 and 52 months of age.

Conclusions and Recommendations for Clinical Practice: 

The importance in this case lies in the use of a multisystem approach to treatment, careful consideration of frequency of intervention, and discussion of the unique features of AHC.

In Brief

The purpose of this case report is to present an example of physical therapy evaluation, intervention, and outcomes for a child with alternating hemiplegia of childhood.

INTRODUCTION

Alternating hemiplegia of childhood (AHC) is a rare neurological disorder characterized by episodes of hemiplegia largely caused by mutations in the ATP1A3 gene.^1,2 Symptoms include seizure-like episodes while the child is conscious,^2–5 generalized weakness,^3,4,6–8 limb stiffening,^3,4 and abnormal eye movements.^2–6,8,9 Paroxysmal features of AHC include nystagmus, dystonia, and hemiplegic spells^2–9 that may switch sides and transition to quadriplegia.⁴ Episodes typically begin in infancy as oculomotor abnormalities with dystonia or hemiplegia.⁵ Hemiplegia in AHC is often flaccid,^3–6 and fluctuating dystonia can influence the child's ability to walk.^3,6,7 The episodes last from a few minutes to 3 weeks,^3,5–7 with frequency ranging from daily to once in 180 days.^2,3,6,7 Episodes are experienced over the course of 1 to 5 years before they become less frequent, with a variable decrease in frequency by adulthood.^2–4 The episodes can be triggered by emotional stress,^3,5,6 fatigue,^3,6 excitement,⁶ trauma,⁶ temperature extremes, crowds, odors, irregular sleep, water exposure, specific physical activities such as exercise or swinging, specific foods, and light sensitivity.⁵

Clinical criteria³ for AHC include 6 distinct features: (1) onset of features prior to 18 months of age; (2) recurrent attacks of hemiplegia involving one or both sides of the body; (3) paroxysmal attacks of oculomotor abnormalities such as nystagmus, tonic or dystonic spells, dyspnea, and autonomic derangements that occur during hemiplegic spells or in isolation; (4) episodes of bilateral hemiplegia that occur during spells that begin unilaterally; (5) resolution of symptoms with sleep, with frequent recurrences upon awakening; and (6) permanent neurologic impairments manifesting as developmental delay, cognitive delay, and neurologic abnormalities such as choreoathetosis, dystonia, or ataxia. A clinical course in 3 phases has been described,⁶ with the first phase characterized by mild developmental delay and abnormal ocular movements. The second phase is characterized by hemiplegic spells, quadriplegic episodes, autonomic phenomena, increased severity and frequency of episodes, dystonia independently or in association with hemiplegic spells, and choreoathetosis between spells. The third phase is characterized by persistent developmental delay and fixed neurological deficits.

It was suggested that AHC is a cerebral degenerative disorder,^10,11 but recent clinical analyses^4,12 argue against the presence of worse motor function in older children. Delayed onset of sitting and walking is common. One cohort¹³ of 10 children with AHC demonstrated delay in onset of sitting (mean 9.3 months, with a range of 8-14 months) and walking (mean 25 months, with a range of 16-72 months). In another cohort⁴ of children and adults with AHC, only 27% were able to walk without help at 2 years of age and 150 of 157 first achieved unaided walking at or beyond 2 years of age. At the onset of walking, gait was unsteady in 84% of children. The influence of physical therapy on motor outcomes in children with AHC has not been described in the literature. The purpose of this case report is to present an example of physical therapy evaluation, intervention, and outcomes for a child with AHC in sequential episodes of care between 14 and 52 months of age. The implications for physical therapy evaluation and treatment of children with AHC have been discussed.

DESCRIPTION OF THE CASE

The child was a 14-month-old girl, born at full term, with the pregnancy complicated by placenta previa and maternal history of migraines. She had 2 maternal half-sisters, one with AHC with ATP1A3 mutation and the other with seizures and autism spectrum disorder. The child's first hypotonic episode occurred at 6 days of age and consisted of inconsolable crying followed by weak suck, right-sided limb weakness, and right facial weakness. These episodes occurred monthly during infancy, with mild right-sided weakness continuing between episodes. She was diagnosed with hypotonia and right hemiplegia; brain MRI and electroencephalography findings were normal. She was prescribed flunarizine at 15 months of age for suspected AHC, but it was discontinued due to an allergic reaction. She was diagnosed with AHC based on clinical criteria at 22 months of age; genetic testing revealed normal ATP1A3 gene sequencing. At 53 months of age, she was diagnosed with an unnamed mitochondrial disorder.

At the initial physical therapy evaluation, she was having episodes of distal dystonia every other day, axial dystonia with rhythmic arm movements weekly, and episodes of screaming followed by hypotonic hemiplegia of right limbs and face. Episodes of dysautonomia first occurred at 15 months of age and continued monthly with fevers and cyanosis of lips and extremities. By 18 months of age, she had experienced 2 episodes of quadriplegia. By 21 months of age, she was having episodes of cyanosis and screaming during sleep but continued to have normal cardiac examinations. The child developed additional symptoms of tremors getting into or out of water, nondistractible echolalia with fluctuating pupils, aggressive behavior, and screaming with facial dystonia and slurred speech. Episodes of hypotonic right hemiplegia increased to daily by 28 months of age, quadriplegic episodes increased to weekly by 52 months of age, and dystonia increased to multiple times per day by 31 months of age.

The child was evaluated by home-based early intervention at 13 months of age. Physical therapy was not initially recommended, but she was seen by a physical therapist twice in the home. Due to increasing concern regarding the child's movement patterns and motor skills, her parents elected for an outpatient physical therapy evaluation. At initial outpatient evaluation at 14 months of age, the child's mother was concerned that her daughter had a left-sided preference and could not clap hands. Family goals were for her to creep on hands and knees and to walk normally. The child first rolled at 6 months of age, first sat independently at 10 months of age, and first pulled to stand at 12 months of age. She was receiving outpatient speech therapy.

The primary problem was right-sided weakness that was more severe during episodes. Spastic hemiplegia was considered as a differential diagnosis. The initial examination tests included posture, muscle tone, flexibility, and the Alberta Infant Motor Scale^14,15 (AIMS) to examine gross motor skills, muscle strength, and quality of movement. Interrater reliability values (r > 0.99) and test-retest reliability values (r = 0.99) have been reported,¹⁴ and high concurrent validity was found between the AIMS and the Peabody Gross Motor Scale¹⁶ (r = 0.99). The Infant-Toddler Sensory Profile¹⁷ was given to the parent to complete.

The examination was completed with the child barefoot, undressed to diaper, and in a carpeted private room with her mother present. Posture and movements were observed in supine, prone, sitting, and assisted standing positions.

The AIMS^14,15 was administered to examine gross motor skills and quality of movement, as it is reliable and valid for children younger than 18 months. Examination of muscle tone, upper extremity (UE) and lower extremity (LE) passive range of motion, and LE flexibility was completed to identify persistent effects of hemiplegia. To examine muscle tone, the child's UEs and LEs were moved to determine resistance to passive stretch. As limbs were moved to examine end feel, no restrictions in muscle flexibility or joint range of motion were identified. Equilibrium reactions were examined in sitting based on the child's initial posture and parent report of left-sided preference.

Gross motor skills were below the 5th percentile for age on the AIMS. Impairments were symmetrically decreased abdominal muscle strength, elevated rib cage with bilateral anterior rib flaring, and decreased strength in right limbs, distal greater than proximal. Strength was examined through observation of functional mobility and assisted transitions. She moved between right and left side sitting, but demonstrated an asymmetrical preferred posture with weight bearing on a fully flexed right knee with left foot forward in weight bearing. She hitched in a similar posture with right hand weight bearing with shoulder internal rotation, elbow extension, and palm open. She stood unsupported for 5 seconds with a wide base of support and then lowered with control using hands on a surface. She took 2 steps with 2-hand support but did not creep on hands and knees, cruise, or walk independently. She appeared content, made eye contact, and showed interest in her mother but did not mimic or vocalize.

Neuromuscular impairments included mild hypotonia and delayed equilibrium and protective reactions to the left in sitting. When assisted to pull to stand, she exhibited right ankle plantar flexion and inversion and only initiated by leading with the left leg. She had reduced variability of movement patterns, asymmetry, and postural instability with poorly controlled weight shifting.

Spastic hemiplegia was ruled out since she lacked spasticity, was hypotonic throughout, and moved between right and left side sitting. Hitching was attributed to mild right extremity hypotonia and weakness, significant motor incoordination for reciprocal extremity movements, and suspected impairment of sensation in her right extremities. Her trunk strength was not asymmetrical based on her ability to rise from the supine position to sit over her right side, but her right LE weakness influenced her ability to achieve quadruped, creep, and walk. A primary impairment of asymmetry in patterns of movement was identified, with decreased initiation of movement patterns for gross motor skills with the right foot in plantigrade. Physical therapy twice per week as an outpatient was initiated. A referral was made to occupational therapy to evaluate the child's cognitive and fine motor skills. Further assessment by neurology was planned given the uncertainty of the child's medical diagnosis.

INTERVENTION

Initial frequency of treatment was considered important due to her age and gross motor status. Without treatment, this child was at risk for developing contractures of right pectorals and left hamstrings based on movement patterns, deformities of rib cage and shoulder girdle, asymmetrical bone development, and falls. She received continuous services for 9 plans of care (Table 1), which varied in frequency, duration, and goals. Frequency of each plan varied between 1 and 2 times per week, and length of each plan was from 3 to 6 months. Frequency and duration of each plan were determined based on age, the degree to which motor skills were established, and rate of progress in the previous plan of care. After stable walking was achieved, frequency was decreased from twice to once per week. Each plan of care included unique goals, but goals that addressed critical components of mobility were continued through more than one plan of care. Her response to intervention, sleep difficulty, medication trials, nutrition, endurance, fatigue, and recovery time from recent episodes guided changes in intervention.

TABLE 1 - Plan of Care Progression^a

Plan 1 Initiated at 14 mo of age; 2×/wk for 4 mo Testing: AIMS: <5th percentile Goals: Creep on hands and knees or hands and feet over obstacle >6 inches high, with reciprocal use of lower extremities without assistance 3/4× Assume a low- or high-half kneel with right foot planted, with hand support, 3× within 10 min Clap hands or sign “more” bringing both hands to midline, demonstrating improved motor coordination and generation of sensory input (18) Walk with symmetric gait 50′ without falling 3/3× Pull to stand or climb up onto a medium-sized bench/child-sized chair, leading with right lower extremity and then climb down safely 3/3× (18)

Plan 2 Initiated at 18 mo of age; 2×/wk for 3 mo Testing at 18 mo: AIMS: below the 5th percentile, PDMS-2: 13th percentile Testing at 20 mo: PDMS-2: 10th percentile Goals: Climb 3″ up incline on hands and feet demonstrating improved LE reciprocation and core strength 3× (22) Climb down stairs or a surface higher than a sofa 3× by turning around and descending feet first, in prone/hands and knees/or hands and feet [(25) with verbal cue] Ascend 6″ stairs with 1 rail with stand by assist Descend 6″ stairs with 1 rail with supervision Rise from floor to stand through half kneel with right foot leading with assist only to establish base of support, with ball or lightweight 2-handed object in hands (hands not on support surface or floor) 3/5×

Plan 3 Initiated at 21 mo of age; 1×/wk for 3 mo Goals: all goals from plan 2 continued

Plan 4 Initiated at 25 mo of age; 1×/wk for 6 mo Testing at 27 mo: GMFM-88: Total = 78%, A = (43) 84%, B = (60) 100%, C = (30) 71%, D = (32) 82%, E = (36) 50%; PDMS-2: 3rd percentile Goals: Ascend four 6″ stairs with 1 rail with stand by assist (27) Descend four 6″ stairs with 1 rail with supervision (27) Walk with varied walking speed (slow and fast) and stop with control without touching surface or falling, in order to pick up a large ball from the floor, 2/3× (26) Rise from floor to stand through half kneel with right foot leading with assist only to establish base of support, with ball or lightweight 2-handed object in hands (hands not on support surface or floor) 3/5× (30)

Plan 5 Initiated at 31 mo of age; 1×/wk for 5 mo Goals: Initiate rising from the floor to stand by shifting her weight to her left knee and then leading with her right foot through half kneel 3/6× Initiate pedaling a tricycle and continue for 5 revolutions with assist only for keeping the steering wheel midline (31) Jump from the ground with a 2-foot take off >2″, and land without falling 3/5× Imitate standing on 1 foot and improve her stability to maintain single-limb stance momentarily on each foot (33)

Plan 6 Initiated at 35 mo of age; 1×/wk for 6 mo Testing at 35 mo: GMFM-88: C = (34) 81%, D = (34) 87%, E = (40) 56% Goals: Initiate rising from the floor to stand by shifting her weight to her left knee and then leading with her right foot through half kneel 3/6× Jump from the ground with a 2-foot take off >2″ 3/5× (37) Jump down from a 4″ step and land on 2 feet 2/3× Pedal trike with foot pedal attachments 15″ with supervision (39) Creep backward down 3 steps 2/3× with verbal cue demonstrating controlled lateral weight shifting at hips and improved abdominal activation, for improved safety with age-appropriate climbing (40)

Plan 7 Initiated at 40 mo of age; 1×/wk for 6 mo Goals: Initiate rising from the floor to stand by shifting her weight to her left knee and then leading with her right foot through half kneel 3/6× [(41) but not maintained] Step over a knee-height obstacle 3/4× demonstrating improved stability in single-limb stance (43) Jump down from a 4″ step and land on 2 feet 2/3× (43) When walking fast for >20′, slow down her walking speed with only a verbal cue, 4/5× (44) Walk 4 steps on a 4″ wide balance beam with SBA (43)

Plan 8 Initiated at 45 mo of age; 1×/wk for 5 mo Goals: Improve strength in right LE and be able to lead with right LE when rising from floor 3/6×, in 3 consecutive sessions Improve balance: walk 5 steps on 4″ wide balance beam independently 4/6× (47) Improve coordination, stability, and sequencing: climb down from high surface through hands and feet, by stepping backward with control, with minimal assist, without verbal cues for sequencing 3/4× Walk outdoors on grassy surface 30′ 5/6×

Plan 9 Initiated at 50 mo of age; 1×/wk for 6 mo Testing at 52 mo: GMFM-88: Total = 95%, A = (51) 100%, B = (60) 100%, C = (42) 100%, D = (39) 100%, E = (55) 76% Goals: Improve strength in right LE and be able to lead with right LE when rising from floor 3/6×, in 3 consecutive sessions (55) Improve coordination, stability, and sequencing: climb down from high surface through hands and feet, by stepping backward with control, with minimal assist, without verbal cues for sequencing 3/4× Walk outdoors on grassy surface 30′ 5/6× (55) Demonstrate single-limb stance momentarily to don pants in standing while leaning on support surface at 1 point of contact (55)

^aFor goals met, age in months at time goal was met is included in parentheses after goal.

Abbreviations: AIMS, Alberta Infant Motor Scale; GMFM-88, Gross Motor Function Scale-88; LE, lower extremity; PDMS-2, Peabody Developmental Motor Scales-2nd Edition; SBA, stand by assist.

These themes of intervention (Table 2) were important in all plans of care: quality of posture and movement, gross motor skill acquisition, safety optimization, collaboration with parent, novel experiences in a sensory-rich environment, modeling and turn-taking in play, and simple verbal cues to support play. Focus of treatment (Table 1) changed over time with the exception of oblique and gluteal activation. Specific interventions to target oblique and gluteal activation were trunk flexion with rotation in sitting for donning and doffing shoes and guiding transitions from prone to sitting with trunk flexion and rotation. The half-kneel position with the right LE leading was an initial focus, and this pattern of movement continued to be emphasized in transitions to standing. In the first 2 plans of care, the half-kneel position was facilitated with arm support on a surface while reaching into a large bucket or toddler kitchen set. As postural control improved, an 8″-diameter ball hanging by an elastic cord from the ceiling was used to prompt repeated transitions between half-kneel and standing with the right LE leading. Holding the ball required both hands in standing. The child lowered to half-kneel to release the ball, which flew into the air but returned near the child. Demonstration and turn-taking increased attention and pleasure in this activity. Building towers and assembling large puzzles were activities in which the child demonstrated a high interest in repetition without frustration or fatigue as the squat and half-kneel positions were facilitated. Integrating postural control into function was a focus from 18 to 52 months of age, with a progression to increasing force production and stability. Stair training began at 25 months, initially to teach the skill but later to improve safety. Tricycle riding was a focus of treatment from 21 to 52 months of age for strengthening, coordination, and visual attention when moving through space. From 27 to 52 months of age, interventions included static and dynamic activities, eccentric control on stairs, and safety. Throughout all plans of care, a sensory-rich environment provided novel but safe places to challenge balance, facilitate climbing, and opportunities for structured and unstructured gross motor play. Orthotic undergarments (SPIO¹⁸) were used initially for stability in standing and then again to increase gait stability due to ataxia. At 2 years of age, a Convaid Trekker adaptive mobility system was recommended for mobility after episode, and at 40 months of age an enclosed adaptive bed was recommended for safety, as she was not able to fall asleep or remain safely in a regular bed. An ankle-foot orthosis was used for a short time after a quadriceps muscle biopsy prompted days of inactivity followed by knee instability. Only occasionally did this child self-select to rest when fatigued, so child education on activity pacing was emphasized from 45 to 52 months of age.

TABLE 2: Themes of Intervention

DESCRIPTION OF OUTCOMES

Nine sequential episodes of care were provided over 38 months. Outcomes were the AIMS,^14,15 Peabody Developmental Motor Scales-2nd Edition (PDMS-2),^16,19 and Gross Motor Function Measure-88 (GMFM-88)²⁰ (Table 2). At the initial evaluation at 14 months of age, the child's AIMS score was below the 5th percentile. She began walking independently at 16.5 months of age, which is earlier than 95.5% of children with AHC.³ Despite the onset of independent walking, her AIMS total score remained below the 5th percentile at 17 months of age, and she scored in the 13th percentile on the PDMS-2. Over the 3 administrations of the PDMS-2, at 17, 20, and 27 months of age, her percentile score declined from 13th to 10th to 3rd percentiles. The stationary subtest standard score changed from normal range to below average and then increased to the normal range. The locomotion subtest standard score changed from below average to poor and remained in the poor range. The object manipulation standard score changed from below average to normal and then declined to the poor range.

At the first administration of the GMFM-88 at 27 months of age, her total score was 78%. Raw scores improved in Sections C, D, and E on the second administration at 35 months of age, and her total score increased to 95% at the final administration at 52 months of age. Qualitative improvements over the time included improved symmetry, improved initiation of transitions with the more involved right LE, and an increasing repertoire of postural responses and equilibrium reactions in all developmental positions.

At 52 months of age, on what her parents called a “good day,” she consistently followed verbal directions, participated in gross motor activities with verbal and intermittent visual cues, and independently pedaled a tricycle. On a “bad day,” which occurred 2 to 4 days per week, she was lethargic, pale, fussy, and did not want to play actively. Unachieved gross motor skills included walking up and down stairs reciprocally hands-free and hopping on one foot. AHC episodes rarely coincided with therapy sessions and did not affect attendance. Therapy was deferred only once due to severity of the child's lethargy. Table 3 includes the International Classification of Functioning, Disability, and Health (ICF)²¹ model for this child at 52 months of age.

TABLE 3 - International Classification of Functioning, Disability, and Health²¹ Model at 52 Months of Age

Health Condition: Alternating Hemiplegia of Childhood; Unnamed Mitochondrial Disorder
Body Structure and Function Impairments	Body Structure and Function Abilities				Age: 52 mo
		Activity Limitations	Activity Abilities	Participation Restrictions	Participation Abilities
Dystonia (mouth, right ankle, distal UE) Coordination (oral, right LE, interlimb) Strength (LE right > left, hand intrinsics) Cardiorespiratory endurance Muscular endurance Gait (unsteady, wide BOS, slight crouch) Increased anterior pelvic tilt Postural control Hypotonia Motor planning Task attention Safety awareness Sensory processing Atypical sleep-wake cycle	Can follow 2-step directions Reciprocal LE Coordination to pedal trike Reciprocal gait pattern Trunk righting Normal foot and LE alignment Normal bone and joint integrity Normal flexibility Head righting	Needs minimum assistance to close supervision to safely navigate uneven surfaces Needs moderate assistance to steer trike Needs extra time for transitions between positions and activities Unable to maintain balance in single-leg stance greater than 3 seconds Needs assistance to put on pants Needs assistance to toilet	Supine to sit using hand on surface Independent floor to stand using hands Able to jump, walk backward and sidestep Can sit unsupported at edge of bed/mat Participates in self-directed solitary play Dons/doffs shoes and socks independently while seated Can communicate verbally Can use each hand to manipulate small toys Can draw human faces Feeds self with utensil but messy Independently walks	Limited community distance ambulation endurance with family (uses adaptive stroller) Decreased ability to participate safely in play with peers outside on playground Not in preschool due to frequency and severity of episodes Decreased participation in group activities	Independent in all age-appropriate floor play positions for peer interaction Able to sit in a chair in a restaurant Able to participate in stationary floor play with siblings
	Contextual Factors
	Personal Strengths	Personal Limitations	Environmental Strengths	Environmental Limitations
	Motivated to participate in active play Playful and social with familiar and new people Can self-regulate by going into quiet space sometimes	Distractible in exciting environments Consistent state regulation challenges Difficulty adapting to changing environments	Family support during sessions and home programming Has access to needed assistive devices (adaptive stroller) Working with providers with experience with her rare diagnosis Connected to community of parents with children with AHC	Siblings with disabilities requiring resources (ie, time and attention)

Abbreviations: AHC, alternating hemiplegia of childhood; BOS, base of support; LE, lower extremity; UE, upper extremity.

DISCUSSION

This case report describes physical therapy for a child who met clinical criteria for AHC without mutation in ATP1A3, without seizures, but with an additional diagnosis of mitochondrial disorder. Because the prevalence of AHC is 1 per 1 million⁸ and the disorder is complex, the clinical signs and symptoms may be misdiagnosed. Epileptic seizures, while not a clinical criterion, are common and can make diagnosis difficult.^4,22 For this child, the parent's knowledge of features of AHC guided initial referral to physical therapy. Health care professionals should be aware of the clinical criteria for AHC to initiate therapy services, as child presentation can vary between among children and within a child. In addition to fatigue secondary to AHC-related episodes and sleep disturbances, this child's mitochondrial disorder may have been an additional contributor to her fatigue.^23,24

Literature is inconsistent regarding motor skill regression in children with AHC,^10–12 with 1 study suggesting rate of progress could be consistent with same-aged peers in children with AHC without mutation.⁹ This child did not lose gross motor skills and began walking independently earlier than 95% of children with AHC.⁴ Despite occasional increased difficulty with preestablished skills or movements for days at a time postepisode, GMFM-88 scores and specific goals met between 14 and 52 months of age demonstrate steady skill acquisition. The child was not enrolled in preschool due to challenges with episode management, which is common for children with AHC.⁴

Frequency of treatment varied per plan of care. The higher frequency (twice per week) between 14 and 20 months of age increased the opportunities to influence critical subsystems²⁵ and for this child may have influenced onset of walking. The themes of intervention provided in the outpatient setting included sensory-rich, novel activities in physical therapy with concurrent occupational and speech therapies. The outpatient setting posed a challenge of frequent transportation to the clinic, which could have influenced this family's quality of life over time. Home-based physical therapy services were not available beyond 36 months of age in the child's geographic location. Within a session, the child's response guided adjustments to the intensity of treatment activities.

Frequent reevaluation was required to target specific needs. The role of the physical therapist included direct intervention to address motor skills, but also collaboration with the family for home exercises, consultation for orthotic garments and adaptive equipment, and collaboration with the multidisciplinary team.

What This Case Adds to Evidence-Based Practice Beyond the Research Literature

The importance of this case report lies in the consideration of a multisystem approach to treatment, specific motor progression, and varied frequency of physical therapy intervention for a child with AHC. The case supports the benefits of an examination that includes postures, movements, tests related to gross motor function, mobility, safety, and consideration of orthotic and adaptive equipment needs. The case provides context for frequent reevaluation of a child with AHC and highlights the influence of specific impairments on function. Capturing existing parameters of physical therapy for intervention along with longitudinal gross motor function for cohorts of children with AHC can continue to guide therapeutic recommendations for this population.