CONFLICTS OF INTEREST The author declares no conflicts of interest.
Kevin P Murphy, Gillette Specialty Healthcare Northern Clinics 1420 East Londen Road, Suite 210, Duluth 55805, MN, USA. E-mail email@example.com
Cerebral palsy (CP) has always been considered a static condition in the neurological sense. Secondary and associated conditions that occur in the patient with CPcan progress over time and cause unwanted sequelae. This paper discusses four musculoskeletal conditions that present across the lifetime and can lead to progressive loss of function in the patient with CP. Patella alta can be particularly painful in the early adult years, limiting mobility particularly when associated with crouch gait. Adults with lower-extremity weight-bearing status having hip dysplasia, progressive over time, often develop pain and severe degenerative arthritis, with or without arthrodesis. Spondylolysis, particularly at the L5 S1 level, is fairly common in the ambulatory adult with diplegia and may, if not diagnosed early, progress to spondylolisthesis. Cervical stenosis appears to be more prevalent in adults with spastic quadriparesis and dystonia and is often associated with myelomalacia and/or radiculopathy. All four of these conditions may be lessened, or even prevented, with intervention and diagnosis in the younger years. Possible interventions and outcomes over time are discussed in the context of multidisciplinary team management of the individual with CP.
By definition, the primary condition of cerebral palsy (CP), in the neurological sense, has always been considered non-progressive over time.1,2 Secondary conditions develop over time as a result of the CP; they include soft-tissue contractures, degenerative arthritis, and equinovalgus foot deformities. These conditions can be prevented with appropriate intervention and early diagnosis.3,4 Associated conditions are those that occur with increased prevalence in individuals with CP; they include visual or auditory impairment, learning disability, and gastroesophageal reflux. These conditions cannot always be prevented, but their impact can be lessened by early diagnosis and intervention during the developmental years. Comorbidities (e.g. diabetes, hypertension) are conditions unrelated to the primary disability. They appear with a similar frequency, regardless of a diagnosis of CP. In the author’s experience, medical care providers too often blame the primary condition for virtually all the symptoms and problems that develop in the adult with CP. Symptoms such as leg pain, discomfort in the lower back, and headaches are too often seen as expected sequelae of living with CP, and no effort is made to pursue a more specific diagnosis. A person presenting with a headache may be told that ‘everybody with cerebral palsy develops headaches at some point in time,’ and no further effort at diagnosis is made. Strauss et al.5 in reviewing the public health record for the State of California, reported a surprisingly higher risk of brain cancer in people with CP. With the patient with CP, as with any individual presenting with symptoms of medical or surgical need, the main initial goal should be to establish a correct diagnosis. This will never be achieved if we too easily attribute loss of function and medical symptoms to the primary condition of CP.
Adults with CP, like other individuals with developmental conditions, are living longer as a result of improvements in medical and surgical care.3,6–14 With aging come certain conditions that can cause pain and significant loss of function. This article identifies four musculoskeletal conditions that may be problematic over the lifetime. The first three are felt to be preventable, and the impact of the fourth can be lessened if the condition is identified and intervention is undertaken during the developmental years.
Patella alta is a relatively common condition in ambulatory adults with CP and spastic diplegia.15,16 It is often associated with anterior knee pain that begins in preadolescence or adolescence and progresses over time. An Insall ratio greater than 117 is generally observed on lateral radiographs (Fig. 1). This ratio is determined by dividing the length of the patellar tendon (measured from the posterior surface of the lower pole of the patella to its insertion on top of the tibial tubercle) by the greatest diagonal length of the patella in at least 30° flexion.17 The ratio should be approximately 1, with less than 20% variation. Not uncommonly, the condition is seen with crouched gait, which limits the distance a patient can walk and contributes to further biomechanical and lever-arm dysfunctions.18–20 Stress fractures may occur at the inferior pole of the patella with palpable tenderness; excision is required when conservative care fails.21 Subluxation and dislocation of the patella are additional complications.22,23
Medical and surgical measures to minimize crouch gait during the developmental and preadolescent years are encouraged. Such measures include maximizing the knee-ankle-foot extension couple and hamstring, quadriceps and hip flexor stretching, and strengthening the weight-bearing soft tissues.18,24–26 Excessive tightness to the rectus femoris muscle can contribute to this and may even facilitate more of a recurvatum deformity.21 In the author’s opinion, more emphasis could be given to quadricep stretching, which may help minimize patella alta in children with CP. Increased prone lying exercises and abdominal strengthening to minimize anterior pelvic tilt should provide additional benefit. In the young and middle-aged patient, benefit may be achieved with taping of the patella into a more midline position so that it can track better within the trochlear groove. Insall and colleagues16 noted that clinical results correlated better with patellar congruence than with severity of chondromalacia at the time of operation. A Neoprene patellar-tracking knee orthosis may further reduce symptoms. Interarticular injections with a long-acting steroid and anesthetic combination can provide relief for 6 months or more. The author has also utilized clostridium botulinum toxin A (BoNT-A) injections to the distal quadriceps mechanism to help relax the superior patellar soft tissues. This is followed by a myofascial technique in ‘milking down’ the patella to a position closer to the center and midline of the knee joint. Physical therapy and nonsteroidal anti-inflammatory agents can be of additional help as part of a conservative care program.
When conservative care is no longer effective in the skeletally mature individual having progressive crouch gait, aggressive surgical options should be considered. These include multilevel operative, including correction of femoral and tibial torsion, equinovalgus foot deformities, distal femoral extension wedge osteotomies, patellar and tibial tubercle advancements, and hamstring lengthening, in addition to rectus femoris transfers.18,20 Close monitoring of the patellar position over the developmental years, with heavy focus on preventive strategies as discussed above, may prevent symptomatic patella alta and the need for more multilevel orthopedic surgery later in life.
Hip dysplasia, weight bearing, and degenerative arthritis
Hip displacement occurs in approximately 1% of patients with spastic hemiplegia, 5% of those with diplegia, and up to 55% of those with quadriplegia.22,27 Pain with degenerative arthritis and joint-spacing incongruity can occur over time in at least 50% of individuals with CP having dislocated hips and/or pseudoacetabular formation.28–31 This problem is of particular concern in an individual having weight-bearing functions in the lower extremities. Weight bearing can be as simple as standing pivot transfers, standing table usage on a regular basis, limited household or community ambulatory skills, and crawling. Pain and osteoarthritic changes can result in a progressive loss of functional weight bearing and mobility. Early identification and intervention in the younger child should prevent significant hip dislocation and pseudoacetabular formation in most individuals. Screening radiographs at least every 6 to 12 months after the age of 18 months should identify subluxation or dysplasia early, with hip and acetabular reconstruction as appropriate thereafter. Managing the hip at risk to flexion contractures less than 20° and functional abduction of at least 45° in extension at 60° in flexion should be helpful.22 BoNTA injections to the adductor longis and hip flexor soft tissues, in addition to phenol obturator neurectomies, can decrease excessive adduction and flexion of the hips.32 Spasticity reduction from intrathecal baclofen can help improve hip positioning and decrease scissoring. This can be combined with a night-time abduction hip orthosis to maintain a more centered position of the proximal femoral head. In the skeletally mature individual with joint space incongruity and severe osteoarthritis, intra-articular injections of a long-acting steroid and anesthetic can provide relief for up to 6 months or more. These injections are often done under fluoroscopy with an arthrogram identifying intra-articular needle placement before assure optimal drug placement and dispersion throughout the articulating surfaces (Fig. 2).
Figure 3 shows severe degenerative arthritis with pseudoacetabular formation (greater at the right than at the left) in a 42-year-old male with spastic diplegia. In the five years before surgery, his ambulatory function had decreased markedly; from more than a mile to less than 10 steps. Severe loss of hip motion was present, limiting hip abduction to less than 15° with near arthrodesis bilaterally. Figure 4 shows the same individual one year after he had undergone bilateral total hip arthroplasties. The right hip was operated on first; the left hip approximately four months later. The surgery was performed by an adult and a pediatric surgeon simultaneously as neither felt comfortable doing the operation alone. The patient can now again walk pain-free almost a mile, using a single-tip cane in the left hand. Total hip arthroplasties have been reported safe and effective for selected individuals with severe degenerative arthritis and pseudoacetabular formation.21,33–35 Constrained acetabular components may be more effective in reducing recurrent dislocation risk, particularly in individuals with dystonia.36 Long-term follow-up studies have shown 94% pain relief and improved function over time, even in patients operated on at the relatively young age of 30 years.37 Wear and tear appears to be minimal, which may relate to the fact that the adult with CP takes fewer steps per day and over time. Proximal femoral head resections, either Castle or Girdlestone type,38,39 may be helpful in individuals who have no weight-bearing status for the lower extremities.
The question of crawling needs to be addressed before any surgical intervention, as most individuals will not offer this information on their own. The author has observed one non-ambulatory individual with a dislocated osteoarthritic hip who crawled within his home. The individual, having never been asked about crawling, had a Girdlestone procedure. This eliminated his ability to crawl. As a result, he could no longer live independently and was forced to enter institutional care. The need to question individuals on crawling behavior cannot be overemphasized.
The possibility of self-injury needs to assessed pre- and postoperatively. Patients can scratch at their own surgical incisions and disrupt traction units and immobilization devices if not carefully managed. Pain management needs to be assessed, especially in individuals with limited communication skills and variations of expression. End-stage hip disease in weight-bearing adults with CP is virtually certain to result in loss of gait and mobility. In such situations, total hip arthroplasty is an attractive option, despite the associated risks and complications.
Spondylolysis is an acquired condition thought to be related to a stress fracture through the pars interarticularis resulting from repetitive hyperextension.15 The prevalence of spondylolysis has been estimated at 4.4% at 6 years of age, increasing to the adult rate of 6% by 14 years of age.40 With one exception, a defect in the pars interarticularis has never been identified at birth.41–44 Spondylolisthesis can be associated with spondylolysis, the development of which is infrequent after the age of 6 years in able-bodied children.22
Reports in the literature have identified the prevalence of spondylolysis in weight-bearing adults with CP with or without dystonia as between 21% and 30%.21,45,46 This prevalence may be higher in individuals who have undergone selective posterior rhizotomy and with associated increased anterior pelvic tilt.47–49 In a series of 143 patients who had never walked and in whom the condition of CP dominated, no cases of spondylolysis or spondylolisthesis were detected radiographically.50 Dystonic involuntary movements through the lumbosacral spine, particularly into extension and axial rotation, appear to contribute to the higher incidences of spondylolysis in this population.45,51Figure 5 displays spondylolysis bilateral at the L5 S1 level in a 35-year-old ambulatory male with cerebral palsy, spastic diplegic type. He had been experiencing back pain for over 3 years (explained by his primary care physician as ‘usual and expected’ for people with CP). His symptoms improved greatly with conservative care, including temporary lumbosacral corset, core strengthening, and pelvic-stabilization routines to decrease anterior pelvic tilt and minimize toe walking. A grade I spondylolisthesis, non-progressive over time, was also noted. Within 6 months of treatment his symptoms had abated and he was again able to enjoy bowling, his favorite recreational sport.
Efforts to minimize anterior pelvic tilt in weight-bearing children with CP may help prevent stress fractures through the pars interarticularis of the lumbar spine. This is particularly important in patients undergoing selective posterior rhizotomy and/or aggressive hamstring lengthening, especially in the presence of tight hip flexor muscles.18 BoNT-A injections may help in the treatment of incapacitating painful dystonia of the lumbar paraspinal muscles52 facilitating optimal sitting and standing postures in the hope of preventing future spondylolysis. Other medications and treatments, along with physical therapy, activity modification, gait aids, and power mobility when necessary, may offer additional protective factors against stress fractures through the pars interarticularis. Careful monitoring through serial radiographs of the lumbar spine in those individuals at increased risk can allow early detection and intervention. Surgical options, including segmental fusion in the presence of failed conservative intervention and any neurological compromise, should be used when necessary. Home exercise, including prone lying techniques; stretching of hip flexors, hamstrings, and gastrocnemius muscle groups; abdominal strengthening; and utilizing appropriate orthotics to minimize toe walking, is always important. Symptomatic pre-stress fractures of the pars interarticularis also need to be considered; nuclear medicine bone scans may assist diagnosis. The patient history should include a review of any falls or injury to the lumbar-pelvic region because the patient may not always recall more-distant traumatic etiologies at the time of medical evaluation.
One study has shown that the incidence of cervical stenosis is higher in adults with CP and athetosis than in other individuals.53 In this study, 180 patients with cerebral palsy and athetosis, when compared with 417 controls, showed an eight-fold increased frequency of early cervical disc degeneration and a six- to eight-fold increase in listhetic instability in the midcervical spine. The combination of disc degeneration with listhetic instability and narrowed spinal canal may predispose these individuals to rapid progressive loss of function and devastating neurological deficit.54
Additional studies have noted that adults with CP and athetosis have higher rates of cervical spondylosis and myelopathy, often associated with dystonic contorsional head and neck postures.55–63
Figure 6 displays an MRI of a 38-year-old male with CP, spastic quadriparesis, and cervical dystonia. Segmental encroachment with canal compromise can be noted, particularly at the C4 and C5 levels. This individual was independent with all of his self-care functions and had limited community ambulatory ability one year before discovery of his cervical stenosis. At time of diagnosis he had stopped walking and lost bladder control; he had also shown signs of increased truncal and lower-extremity spasticity in the preceding 6 months. Surgical decompression with posterior fusion and wiring was provided and the patient regained his former ability to walk and engage in self-care functions within 8 months. The individual aspirated upon intubation at the time of surgery and required an additional 2-month stay in the intensive-care unit. Twelve years after surgery, he maintains independent living skills, can walk, and requires minimal supervision within his community group home residence.
Serial MRIs every 2 years in individuals at higher risk, beginning in young adulthood, may help identify cervical spondylosis and stenosis early and allow for proactive intervention and prevention of unwanted sequelae. BoNT-A injections, along with postural adjustments and supports, may help minimize cervical dystonia, particularly into extension and axial rotation.52 Medications for control of dystonia are encouraged, including intrathecal baclofen therapy in carefully selected individuals. Placing the patient in a calm environment, use of sensory biofeedback techniques, and stress reduction may also reduce regional dystonia. The author can recall a patient who, when flying alone in her glider plane, was completely relieved of her dystonic features until touchdown, when the ground support staff would come to her assistance. Cervical discomfort of any sort should be taken seriously in this population, as it may be the only sign of more-devastating neurological compromise. Serial neurological examinations adapted for individuals with CP are encouraged. Measurement of certain reproducible voluntary motor functions over time, using a clinically reproducible spasticity measure, is suggested. Close monitoring of bowel and bladder functions for changes in frequency, urgency, retention, and continence is advisable. Should conservative measures fail, surgical decompression of the stenotic cervical canal may be required. There is a tendency toward a more anterior approach and interbody fusion with posterior wiring.59,62,64–66 The high risk of surgery, including regional dystonia in the surgical zone, aspiration potential, bleeding, and limited options for utilization of immobilization devices, should not be overlooked. Nonetheless, cervical stenosis associated with serious functional loss over time is rapidly progressive in this population. For this reason, surgical intervention seems warranted when conservative care has failed to maintain function and a comfortable lifestyle. Early identification and intervention can, it is hoped, help prevent the unwanted sequelae of cervical stenosis in this population or at least minimize the surgical intervention required to accomplish that objective.
Four musculoskeletal conditions have been discussed within the context of lifetime care for the individual with CP. Further investigation and study seem warranted, in view of the progressive nature of these four conditions. Other, yet to be identified secondary and associated conditions are likely to be present, both within and outside of the musculoskeletal system, in the adult with CP. Medical providers should take care not to blame symptomatology on the primary condition of CP when other etiologies exist. Early identification and intervention to prevent unwanted loss of function and lifestyle are the ultimate goals.