The ABCs of MHE - Continued

How MHE Can Affect Each Part of the Body

 

 

MHE usually manifests during early childhood more commonly with several knobby, hard, subcutaneous protuberances near the joints.

 

The likelihood of involvement of various anatomical sites as observed in a large series is as follows:

 

Anatomical location & Percentage involvement

Distal femur: 70%

Proximal tibia: 70%

Proximal fibula: 30%

Proximal Humerus: 50%

Scapula: 40%

Ribs: 40%

Distal radius and ulna: 30%

Proximal femur: 30%

Phalanges: 30%

Distal fibula: 25%

Distal tibia: 20%

Bones of the foot: 10-25%

 

THE SKULL

Lesions in the skull, although reported are extremely rare. Mandibular osteochondromas, typically of the condyle, skull wall lesions and even intracranial lesions have been reported.

 

Affects of MHE on Skull

Exostoses can cause problems if they compress or entrap cranial nerves or cause extrinsic compression on the brain. Effects can range from bumpy external lesions that cause cosmetic problems, compression of adjacent structures, cranial nerve involvement and even focal neurological deficits due to compression. Even seizures are likely due to intracranial lesions.

 

Diagnostic Procedures

The orthopedist will manually feel for exostoses along the outer table of the skull, check movements of the mandible and also of the upper cervical spine. The orthopedist will also check cranial nerve function and perform a thorough neurological evaluation. X-rays or other imaging tests including CT and MRI may be ordered.

Possible Treatment Options

  • Minor lesions on the outer table of the skull that are flat can sometimes be closely observed.

  • Bigger lesions on the skull, mandibular lesions causing TM joint instability, and intracranial lesions causing pressure signs may need to be removed by neurosurgical intervention.

  • Upper cervical spinal tumors, especially of the atlanto-occipital region may be dealt with by orthopedists. Decompression and or stabilization may be performed as required.

 

What Parents Should Watch Out For

  • Pain.  Is your child experiencing pain from exostoses?

  • Visible lumps on the face or skull.

  • Any symptoms of tingling, numbness, weakness in the hands or legs suggestive of focal deficits.

  • Episodes of seizures or findings of cranial nerve involvement like altered smell, taste, ringing in ears etc.

  • Problems in chewing, restricted motion of the jawbone or instability of the mandible.

  • Parents can ask dentists and orthodontists to be on the lookout for signs suggestive of jawbone instability or joint involvement during their office visits especially in symptomatic cases.

SPINE      

 

The spine extends from the base of the skull to the tailbone. Spinal exostoses are rare (Figure 1). Spinal cord impingement is also a rare, but documented, complication of MHE. Cervical, thoracic or lumbar region can be affected. Scoliosis secondary to spinal osteochondromas and instability has been reported.  


Affects of MHE on the Spine: 

This section of the body is not commonly involved with MHE. Involvement of isolated vertebrae has been noted. Affects can range from instability to neural root or cord compression that can manifest as tingling, numbness or weakness in the involved roots or even major neurological deficits like paraparesis or quadriparesis in untreated cases. Rarely compression effects in the form of dysphagia, intestinal obstruction or urinary symptoms may occur.

 

Diagnostic Procedures:

With any of the red flags mentioned earlier, the orthopedist will perform a thorough spinal and neurological evaluation. Plain x-rays of the spine and if required, advanced imaging may be performed. The presences and extent of the lesion are best delineated with CT, while MRI of the spinal cord demonstrates the area of spinal cord impingement. In rare cases of peripheral nerve compression electromyography may be performed to check status of the nerve.

 

Possible Treatment Options:

  • Minor lesions not causing compressive symptoms or neurologic manifestations may be kept under close observation.

  • Progressive scoliosis and spinal instability may need to be treated with surgical stabilization involving spinal fusion.

 

What Parents Should Watch Out For:

  • Any red flags in terms of tingling, numbness, weakness, night pain or bladder and bowel changes and get them evaluated.

  • Any deformity in the spine or evidence of shoulder or pelvic imbalance.

  • Gait or posture disturbances. Remember that gait and posture disturbances can be caused by hip or leg exostoses as well (due to either limb-length discrepancy or deformity) and do not necessarily mean tumors in the spine. In any case evaluation by a clinician is important.

 

RIBS AND STERNUM

The typically flat bones of the ribs are prone to effects of MHE, with approximately 40% of MHE patients having rib involvement. Prominent chest wall lesions are common although intrathoracic lesions including rare presentations like spontaneous hemothorax (build-up of blood and fluid in the chest cavity) as a result of rib exostoses have been described. Typically, these lesions create issues of cosmesis due to their obvious visibility.   Other symptoms may include shortness of breath and other breathing difficulties, pain when taking a deep breath, when walking or exercising, or pain from exostoses “catching”.

 

Diagnostic Procedures

The orthopedist will probably manually feel for exostoses along the chest wall and the ribcage. Size and extent of the lesions are noted. A thorough pulmonary evaluation is warranted in all cases when specific symptoms of cough, chest pain or breathing problems are encountered. X-rays or other imaging tests may be ordered.

 

Possible Treatment Options:

  • Minor bumps can sometimes be kept under observation.

  • Cosmetic problems, rapid increase in size, large size, and signs of compression are some indications for early removal.

  • Consult may be required with specialists:

Pulmonary: when there are severe breathing difficulties with increasing chest pain.

Thoracic surgeons: when intrathoracic (within the chest wall) exostoses may need to be excised.

 

What Parents Should Watch Out For:

  • Breathing difficulties, shortness of breath

  • Pain when taking deep breath.

 

SHOULDER GIRDLE

 

The scapula is a fairly common site (40%) of involvement in MHE. The lesions may be located on the anterior or posterior aspect of the scapula. Anterior scapular lesions may lead to discomfort during scapulothoracic motion. Winging of the scapula due to exostoses has been described. Clavicle (collar bone) involvement has also been described (5% cases).

 

What is winging?

The scapula (also known as shoulder blade) is a triangular flat bone that is located in the upper back and takes part in forming the shoulder joint. The scapula usually lies flat on the chest wall without any prominence. Winging of the scapula is a phenomenon when a part of the scapula including the inferior angle becomes prominent either at rest or during movements. The two most common causes for this are

  • Exostosis on the inner (chest wall) aspect of the scapula.

  • Damage to the nerve (long thoracic) causing weakness or paralysis of muscles (serratus anterior) attached to the scapula.

 

Diagnostic Procedures

The orthopedist will probably manually feel for exostoses along the outer aspect of the shoulder blade. Some limited areas of the inner aspect are amenable to clinical examination. Range and feel of the scapulothoracic motion is helpful in clinical assessment. It is important to check individual groups of scapular muscles to rule out nerve compression leading to winging of scapula. X-rays (including special tangential views of the scapula) or other imaging tests may be ordered.

 

Possible Treatment Options

  • Both outer aspect lesions and inner ones may need excision in symptomatic cases. Smaller lesions on outer aspect amenable to clinical palpation may be observed with regular clinical follow-up.

 

What Parents Should Watch Out For:

  • Crunching or crackling sound when moving that area

  • Pain

  • Tingling, numbness

 

Note from The MHE Coalition:  Exostoses in the shoulder girdle (collarbone (clavicle) and shoulder blade can impact a child’s ability to raise his/her arm in class, write on a blackboard, participate in certain sports, or wear a backpack.  In addition, adolescent girls (and women) may be unable to wear a bra because of pressure not only on shoulder girdle exostoses but also on rib exostoses.

 

ARMS

  • Upper Arm (Humerus)

  • Elbow

  • Forearm (Radius and Ulna)

  • Wrists

 

The arm bone is called the humerus while the forearm bones are the radius (curved bone) and the ulna (straighter bone of the two).

 

Osteochondromas of the arm are often readily felt but rarely cause neurologic dysfunction (Figure 2). Osteochondromas of the upper extremities frequently cause forearm deformities.  The prevalence of such deformities has been reported to be as high as 40-60%.  Disproportionate ulnar shortening with relative radial overgrowth has been frequently described and may result in radial bowing.  Subluxation or dislocation of the radial head is well-described sequelae in the context of these deformities.

 

The length of forearm bones inversely correlates with the size of the exostoses.  Thus, the larger the exostoses and the greater the number of exostoses, the shorter the involved bone.  Moreover, lesions with sessile rather than pedunculated morphology have been associated with more significant shortening and deformity.  Thus, the skeletal growth disturbance observed in MHE is a local effect of benign growth. Exostoses in the forearm are known to involve both the radius and the ulna. Since movements of the forearm (pronation and supination) are dependant on the radius moving in an arc of motion around the ulna, mobility may be restricted depending upon the severity of presentation. Also the lower end radius exostoses can lead to compression of the median nerve (in a closed space at the level of the wrist called the carpal tunnel) and present with weakness, tingling and numbness in the hand. Exostoses in the carpal bones can seriously hamper the wrist motion and cause pain.

 

Complete dislocation of the radial head is a serious progression of forearm deformity and can result in pain, instability, and decreased motion at the elbow.  Surgical intervention should be considered to prevent this from occurring.  When symptomatic, this can be treated in older patients with resection of the radial head. 

 

Diagnostic Procedures:

The orthopedist will clinically feel for exostoses along the arm, elbow and forearm, and check range of motion (“ROM”) by moving the arm in different directions. The orthopedist will also check measurements on each arm and forearm to see if there is a difference. X-rays or other imaging tests may be ordered.

 

Possible Treatment Options:

Indications for surgical treatment include painful lesions, an increasing radial articular angle, progressive ulnar shortening, excessive carpal slip, loss of pronation, and increased radial bowing with subluxation or dislocation of the radial head

  • Minor lesions can sometimes be observed with careful follow up.

  • Bowing and some length discrepancies and be treated with a surgical procedure called “stapling,” where surgical staples are inserted into the growth plate of the bone growing faster than the other. This will hopefully give the slower growing bone the chance to “catch up” and the forearm will straighten over time.

  • Limb Lengthening with a fixator. (See Section on Fixators)

  • Resection of the radial head

  • Excision of exostoses

  • Osteotomy

  • Epiphysiodesis

  • Non-surgical measures for treatment of soft-tissue compression, irritation or inflammation (anti-inflammatories, heat, rest, etc.)

  • Adaptive devices to aid those with shortened forearms, such as grippers, long-handled sock aides, etc. 

 

 

What Parents Should Watch Out For:

  • Any red flags in terms of sudden increase in size of swelling, pain, nerve compression, tingling, numbness, or weakness.

  • Possibility of exostoses irritating or catching on overlying tissue, such as muscles, tendons, ligaments, or compressing nerves.

  • Loss of range of motion

  • Pain

  • Difficulty and/or pain when raising arm(s), lifting, carrying

 

HANDS AND FINGERS

 

Hand involvement in MHE is common.  Fogel et al. observed metacarpal involvement and phalangeal involvement in 69% and 68%, respectively, in their series of 51 patients.  In their series of 63 patients, Cates and Burgess found that patients with MHE fall into two groups: those with no hand involvement and those with substantial hand involvement averaging 11.6 lesions per hand.  They documented involvement of the ulnar metacarpals and proximal phalanges most commonly with the thumb and distal phalanges being affected less frequently.  While exostoses of the hand resulted in shortening of the metacarpals and phalanges, brachydactyly was also observed in the absence of exostoses.

 

Diagnostic Procedures:

The orthopedist will manually feel for exostoses in the hands and check range of motion (“ROM”) in different directions. X-rays or other imaging tests may be ordered.

 

Possible Treatment Options:

  • Isolated lesions growing rapidly, or interfering with the smooth motion of tendons or joint motion may need to be excised. Multiple surgeries for small, insignificant lesions is usually not advocated.

  • Occupational therapy, physical therapy

  • Use of pencil grips, laptop computers, and other adaptive devices

 

What Parents Should Watch Out For:

  • Complaints of pain when writing

  • Some children will not complain of pain, but will have poor penmanship, write slowly, avoid writing, etc.  Parents should also observe how the child holds writing and eating utensils.

  • Difficulty in rotating hand(s),

 

 

PELVIC GIRDLE (HIPS AND PELVIS)

 

Osteochondromas of the proximal femur (Figure 3) may lead to progressive hip dysplasia. There have been reported cases of acetabular dysplasia with subluxation of the hip in patients with MHE. This results from exostoses located within or about the acetabulum that may interfere with normal articulation.

 

 

Pelvic lesions (Figures 4 and 5) may be found on both the inner as well as outer aspect of the pelvic blades. Large lesions may cause signs of compression, both vascular and neurological. There have also been reports of exostoses interfering with normal pregnancy and leading to a higher rate of Cesarean sections.

 

Diagnostic Procedures

Manual palpation is sometimes very difficult in these deep lesions. The orthopedist will check range of motion (“ROM”) by manipulating (moving) the leg in different directions. The orthopedist will also check measurements on each leg to see if there is a difference in limb lengths. X-rays or other imaging tests may be ordered.

 

Possible Treatment Options

  • Minor length discrepancies can sometimes be effectively treated with the use of orthotics (specially made shoes or lifts that will equalize leg length).

  • Bowing and some limb length discrepancies can be treated with a surgical procedure called “stapling,” where surgical staples are inserted into the growth plate of the leg bone growing faster than the other. This will hopefully give the slower growing bone the chance to “catch up” and the limb will straighten over time.

  • Limb Lengthening with a Fixator.   (See Section on Fixators)

  • Pelvic lesions of concern may need to be surgically excised.

  • Osteotomies.

  • Hip replacement.

 

What Parents Should Watch Out For

  • Limping

  • Pain in hips, back, legs

  • Pain, discomfort, difficulty in sitting

  • Inability to sit “tailor” style

  • Stiffness in hips and/or legs after sitting

  • Pain and fatigue from walking

 

Continued...

 

 

 

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