Diagnostically Directed Examination for Neurological Disorders

M. Wade Shrader

A. Noelle Larson

• Introduction

Patients with neurological conditions present with discrete physical examination findings. Pattern recognition is important for diagnosis and treatment. Although in many instances, the condition is evident at birth, other presentations may be subtle and are identified by the orthopedic surgeon in infancy, childhood, or even adolescence. Thus, a basic neurologic examination should be routinely performed for all patients, especially those presenting with gait disturbance or spinal complaints. Further, pattern recognition and familiarity with common presentations is needed to promptly diagnose specific disease entities and conditions.

• Cerebral Palsy

With an incidence of 2 to 4 per 1000 live births, cerebral palsy (CP) is the most common motor disability of childhood. CP is a static encephalopathy characterized by an upper motor neuron disease that causes abnormality in muscle tone, selective motor control, strength, balance, and coordination. Typically caused by an ischemic event, the most common etiology today is periventricular leukomalacia (PVL) from prematurity. Hypoxic birth events and intrauterine strokes are less common but constitute a small percentage of patients with CP. Although the neurological injury is static and does not change over time, the effects of time, growth, and developmental delay along with the abnormal muscle tone make the clinical picture of CP quite variable over a child’s growth. One common way to characterize severity is with the Gross Motor Functional Classification System (GMFCS) (Figure 5.1), which is reliable and repeatable over time and correlates closely with other measures of function. In this system a patient is classified as follows: Level I: walks and runs without difficulty; Level II: walks; no aids; needs support for stairs or uneven ground; Level III: walks with aids (canes, walker); Level IV: stands or weight bears for transfers with assistance; predominately uses wheelchair for mobility; and Level V: no functional weight bearing; wheelchair for mobility.

Other neurological conditions mimicking a CP-like condition include perinatal infections with subsequent encephalopathy, congenital brain malformations (such as Dandy-Walker syndrome or agenesis of the corpus callosum), postnatal hypoxic events (like nonaccidental trauma or near drowning), or certain chromosomal disorders. Hereditary spastic paraplegia may have a similar presentation as CP, but patients experience progressive spasticity in the legs only.¹ These “CP-like” conditions are subtly different than the typical ex-preemie with PVL or a child with perinatal hypoxic event, but the majority of the clinical features of these disorders can be grouped together with CP, and significant efforts should not be expended to parse those patients away from a typical CP-clinic environment.

FIGURE 5.1 The Gross Motor Function Classification System (GMFCS) allows caregivers to quantitate the functional ambulatory ability of children with cerebral palsy. (Used with permission from Palisano RJ, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B: Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol. 1997;39(4):214-223. Illustrated by Kerr Graham and Bill Reid, The Royal Children’s Hospital, Melbourne.)

Specific Physical Examination Findings

Neurological Examination

Spasticity—Ashworth Scale

The Ashworth scale is the most common method to quantify increased motor tone. This scale is a manual scale that evaluates resistance of motion of a specific joint (Table 5.1). The original scale was only designed to measure hypertonicity or spasticity. The modified scale allows the examiner to document hypotonia, which can be found in children with CP. This common scale is unfortunately very subjective and at times difficult for the examiner to differentiate overall muscle stiffness from spasticity.³

Deep Tendon Reflexes

The Babinski sign is a test to determine an upper motor brain lesion, which is common in CP. The lateral side of the foot is rubbed with a relatively sharp, but blunt instrument, and it is run from the heel along a curve to the toes. A normal flexor response, the toes flex in response. An extensor, or abnormal response, the big toe extends, and the other toes fan out. This is a positive sign that indicates an upper motor neuron deficit (brain or spinal cord). Deep tendon reflexes (DTRs) in the child with CP may be markedly abnormal. For those patients with significant hypertonicity, the DTRs will likely be brisk and abnormal. Along with the increased DTRs, the patient may have significant ankle clonus with sustained beats.

Dystonia

Dystonia is a movement disorder that has a torsional component along with muscle contractions with recurrent major movement patterns. Dystonia may occur in a single limb, in a single joint, or as a whole-body generalized movement pattern. Dystonia is a movement disorder that is very common in CP. Although patients may have a primary spastic pattern of CP, there are some common elements of underlying dystonia. Dystonia can be measured using the Hypertonia Assessment Tool.⁴

• Hip

Children with CP are at risk for progressive hip displacement, and this can lead to stiffness; limited motion; difficulty with sitting and perianal cares; and possibly pain from late arthrosis. The rate of hip displacement increases with the clinical severity; for instance, patients who have spastic quadriplegia who are nonambulatory (GMFCS V) may have hip subluxation/dislocation in 75% of cases. The hip examination in children with CP is a crucial part of the physical assessment. Attention to detail and reproducible measurements is vital to help determine changes in the pathophysiology and can help predict which patients are prone to hip displacement even before hip radiographs are obtained.

Table 5.1 Ashworth Scale

SCORE	DESCRIPTION OF THE MUSCLE TONE
00	Hypotonia
0	Normal tone
1	Slight increase (slight catch and release or minimal resistance to joint ROM)
1+	Slight increase (slight catch and minimal increased resistance to joint ROM for more than half the joint range)
2	More marked increase through most of the whole joint range, but affected joint is easily moved
3	Considerable increase (passive movement difficult but possible)
4	Joint cannot be moved

General Examination

Range of motion is assessed in all planes: flexion-extension, internal-external rotation, and abduction-adduction. Sagittal plane motion (flexion and extension) is best measured in the supine position, with the limb of interest slightly off the edge of the table so you can determine true extension. Many children with CP will have hip flexion contractures, which is masked by compensatory lumbar lordosis. In these cases, the Thomas test is performed as described below.

Rotation is best measured prone, where the examiner can truly determine the rotational profile of the entire lower extremity including the tibia. With care taken to keep the pelvis neutral and level, the knee is flexed to 90°, rotated outwardly to the maximal excursion to measure hip internal rotation, and rotated inwardly to measure hip external rotation (Figure 5.2).

FIGURE 5.2 Hip internal and external rotation is best assessed in the prone position. This child has 15° of right hip internal rotation with 85° of external rotation.

Hip Abduction

The measurement of hip abduction is especially important in CP; patients with severe limited hip abduction are considered at risk for hip displacement and radiographs are indicated (Figure 5.3).
Hip abduction can be measured with a goniometer with the hips and knees extended in order to isolate the effects of hamstring tightness on abduction (Figure 5.4). While abduction in extension, the examiner should have his/her hand on the pelvis to make sure there is no coronal plane pelvic rotation. Asymmetric hip abduction should be a warning sign to the examiner of the higher risk of hip dysplasia and should trigger an anteroposterior (AP) pelvis radiograph.

FIGURE 5.3 This child with cerebral palsy has limited hip abduction in the supine position. These hips are at risk for displacement and a radiograph should be obtained to assess hip status.

FIGURE 5.4 A goniometer can be used to quantitate the amount of hip abduction, usually with the hip extended. (Figure provided by Dr. Ismat Ghanem.)

The spasticity of the hip adductors can be an important factor when measuring hip abduction. For this reason, two measurements of hip abduction with knee/hip flexion is important to measure: the modified Tardieu joint angles, R1 and R2. R1 is the measurement of hip abduction in a fast, initial movement of maximum attempted hip abduction; the maximum hip abduction will be halted by the catch or clonus that is the hallmark of spasticity. R2 is the second measurement with a slower, more gradual hip abduction maneuver. This allows the examiner to account some of the effect of true spasticity on this important angular measurement.

Galeazzi Sign

The difference in apparent limb length with the hips and knees flexed to 90° is a positive Galeazzi sign (Figure 5.5). Usually, this indicates significant hip dysplasia and possible hip dislocation, and the examiner should ensure that an AP pelvis radiograph is obtained.

FIGURE 5.5 The child in Figure 5.3 has a dislocated left hip as noted by the shortened length of the femur, otherwise known as a positive Galeazzi sign.

Thomas Test and Modified Thomas Test

Hip flexion contracture is a common pathology in ambulatory CP; yet it can be hard to detect as pelvic and lumbar lordosis can mask a true hip flexion contracture. The Thomas test can be performed to detect and measure a hip flexion contracture. With the patient supine on the examination table, the contralateral limb is flexed to the chest, and the examiner attempts to fully extend the opposite limb. When the examiner is holding the opposite knee to the chest, it flattens out the lumbar lordosis and keeps the pelvis relatively stable. If a hip flexor contracture (usually iliopsoas) is present on the other side, the affected limb will not be able to lay flat on the examination table (Figure 5.6). Examination tip: The examiner must remember that many patients who are being tested for hip flexion contractures can have concurrent knee flexion contractures which can prevent the leg from lying flat during the Thomas test and thus imply that there is a flexion contracture. In these patients, the hip to be tested for hip flexion contracture should have the leg and foot hanging over the edge of the bed.

On occasion, the rectus femoris muscle can contribute to hip flexion contracture (Figure 5.7A) and can be suspected when the rectus tendon is well defined and easily palpated from the rest of the quadriceps tendon above the patella (Figure 5.7B). Rectus tightness becomes highly suspected when the affected limb is taken off of the table and the knee does not fully flex with gravity (Figure 5.7C); rectus tightness is confirmed when further knee flexion (modified Thomas test) causes the hip to flex (Figure 5.7D).

FIGURE 5.6 In the top panel, the child’s legs lay flat on the bed and a hip flexion contracture is accommodated by the compensatory lumbar lordosis. The Thomas test is used in the lower panel to assess for hip flexion contracture: by flexing the hip, the opposite hip flexion contracture is now unmasked.

FIGURE 5.7 A hip flexion contracture can be due to psoas and/or the rectus femoris tightness. In Panel A, this patient has a positive Thomas test. In Panel B, the clinician is palpating a very tight rectus femoris tendon which could be the cause of the contracture. In Panel C, the clinician allows the leg to hang over the side of the bed. The fact that the thigh can lay flat implies the psoas is not the cause of the hip flexion contracture. When the knee is flexed in Panel D, tightening the quadriceps, there is further hip flexion, confirming the rectus femoris is tight.

Craig Test to Assess Femoral Anteversion

Although most normal adults have some amount of femoral anteversion (around 15°-20°), many patients with CP have excessive femoral anteversion (>45°) and are noted with significantly more internal rotation than external rotation in the prone position (Figure 5.8). The test to measure femoral anteversion
is also known as the Craig test. The patient’s hip and knee are flexed to 90° of flexion. The examiner rotates the hip medially and laterally, while palpating the greater trochanter area, until the outward most point is found in the lateral aspect of the hip (the greater trochanter is parallel to the table at this point) (Figure 5.9). In individuals with severely limited hip motion, this examination may be difficult. The examiner then measures the angle of the hip to determine the amount of anteversion, using the long axis of the tibia.

FIGURE 5.8 This child with spastic diplegia has excessive femoral anteversion, as noted by internal rotation of the hip to 80°.

FIGURE 5.9 The Craig test allows one to estimate anteversion: The hip is internally rotated until the greater trochanter is most prominent. The angle of the femur to a perpendicular line suggests the amount of anatomic anteversion of the femoral neck in relation to the shaft of the femur.

Unique Hip Positions

In most patients with CP, there is a predominance of increased tone and contractures of the psoas and adductor tendons and the leg is flexed and adducted. With this pattern the hip can become dislocated, and in these instances the hip is usually dislocated in a posterior-superior direction (Figure 5.10). In
rare patients with extensive tone in the hamstrings and hip extensor muscles, the hips are abducted with extension and external rotation. In some of these patients, the hip can be displaced anteriorly and these patients will have bony prominence palpable in the groin (Figure 5.11). Finally, in some patients with asymmetric tone, a windswept hip positioning (sometimes this is an iatrogenic problem from treatment) can occur with one hip abducted while the other hip is adducted (and at this latter hip) and is at risk for dislocation (Figure 5.12).

FIGURE 5.10 A pelvis x-ray and CT scan demonstrate superior and posterior displacement of the proximal femur in this child with spastic quadriplegia who is a GMFCS Level V. Most hip displacements in these patients are in this direction as a result of hip flexion and adduction contractures.

FIGURE 5.11 This child has rare anterior dislocations of the femoral heads. On the clinical picture to the left, one can note the prominences of the femoral head in the groin. In contrast to the prior patient in Figure 5.10, this child has hip abduction and extension contractures. The CT scan demonstrates the femoral head to be dislocated anteriorly.

FIGURE 5.12 A windswept hip deformity is noted clinically by having one hip abducted and the contralateral hip is adducted. The adducted hip is prone to hip displacement as noted in the pelvis x-ray.

• Knee

The knee examination is typically focused on ambulatory patients with CP, although nonambulators may have important knee pathology, as well, such as patellar instability and fixed contractures. Typically, patients with GMFCS Levels IV and V function tolerate mild to moderate knee flexion contractures, and treatment for these contractures that do not interfere with quality of life is unnecessary.

FIGURE 5.13 This child has a knee flexion contracture approaching 30°. The knee flexion contracture is assessed with the hip extended to remove any effect from hamstring tightness.

General Examination

The knee examination in CP usually is focused on range of motion. There is rarely ligamentous instability in CP, but a general stability examination of the knee joint should be performed. It is important to determine active and passive ROM and further to understand the difference between tight hamstrings and knee flexion contractures. CP patients with tight hamstrings may have knees that can fully extend (no knee flexion contracture); but all CP patients with knee flexion contractures (Figure 5.13) have tightened hamstrings. Rarely patients can have severe quadriceps spasticity and muscle tightness that lead to extension contractures (inability to flex the knee) (Figure 5.14). These are rare patterns and can be seen in patients with total brain injury that occur postnatally (near drowning patients).

FIGURE 5.14 A, The child has bilateral knee extension contractures and calcaneus foot deformity. B, Knee hyperextension is noted on exam. C, There is also restricted knee flexion.

FIGURE 5.15 The popliteal angle allows one to quantitate the amount of hamstring tightness. With the patient supine, the hip is flexed at 90° (which tensions the hamstrings) and the knee is extended until resistance is met.

Popliteal Angle

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