Klinefelter syndrome (KS), also known as 47, XXY is the set of symptoms that result from two or more X chromosomes in males. The primary features are infertility and small poorly functioning testicles. Often, symptoms are subtle and subjects do not realize they are affected., symptoms are more evident and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. Often it is only at puberty that these symptoms are noticed.  Intelligence is usually normal; however, reading difficulties and problems with speech are more common. Symptoms are typically more severe if three or more X chromosomes are present (48,XXXY syndrome or 49,XXXXY syndrome).

Klinefelter syndrome occurs randomly. The extra X chromosome comes from the father and mother nearly equally. An older mother may have a slightly increased risk of a child with KS. The condition is not typically inherited from a father with the syndrome. The syndrome is defined by the presence of at least one extra X chromosome in addition to a Y chromosome yielding a total of 47 or more chromosomes rather than the usual 46. KS is diagnosed by the genetic test known as a karyotype.

While no cure is known, a number of treatments may help. Physical therapy, speech and language therapy, counselling, and adjustments of teaching methods may be useful. Testosterone replacement may be used in those who have significantly lower levels. Enlarged breasts may be removed by surgery. About half of affected males have a chance of fathering children with the help of assisted reproductive technology, but this is expensive and not risk free. XXY males appear to have a higher risk of breast cancer than typical, but still lower than that of females. People with the condition have a nearly normal life expectancy.

Klinefelter syndrome is one of the most common chromosomal disorders, occurring in one to two per 1,000 live male births. It is named after American endocrinologist Harry Klinefelter, who identified the condition in the 1940s. In 1956, the extra X chromosome was identified as the cause. Mice can also have the XXY syndrome, making them a useful research model.

Signs and symptoms include:

longer than average to sit up, crawl and walk

Delay in speaking

Problems at birth, such as testicles that haven't descended into the scrotum

Boys and teenagers

Taller than average stature

Longer legs, shorter torso and broader hips compared with other boys

Absent, delayed or incomplete puberty

After puberty, less muscle and less facial and body hair compared with other teens

Small, firm testicles

Small penis

Enlarged breast tissue (gynecomastia)

Weak bones

Low energy levels

Tendency to be shy and sensitive

Difficulty expressing thoughts and feelings or socializing

Problems with reading, writing, spelling or math

The brachial plexus passes from the neck to the axilla and supplies the upper limb. It is formed from the ventral rami of the 5th to 8th cervical nerves and the ascending part of the ventral ramus of the 1st thoracic nerve. Branches from the 4th cervical and the 2nd thoracic ventral ramus may contribute.

 

Compression of the medial, lateral and posterior cords of the brachial plexus can occur between the first rib and clavicle (known as thoracic outlet) and below pectoralis minor 

 

 

The right brachial plexus with its short branches, viewed from in front.

Function

The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the trapezius muscle innervated by the spinal accessory nerve (CN XI) and an area of skin near the axilla innervated by the intercostobrachial nerve.

 

Description

Path

The brachial plexus is divided into Roots, Trunks, Divisions, Cords, and Branches. There are five "terminal" branches and numerous other "pre-terminal" or "collateral" branches that leave the plexus at various points along its length.

 

The five Roots are the five anterior rami of the lower four cervical and first thoracic nerve roots (C5-C8, T1) after they have given off their segmental supply to the muscles of the neck. These Roots merge to form three Trunks:

Upper Trunk (C5-C6)

Middle Trunk (C7)

Lower Trunk (C8, T1)

Each Trunk then splits into anterior and posterior divisions, to form six Divisions. The anterior/ posterior divisions innervate flexor groups versus extensor groups:

anterior divisions of the upper, middle, and lower trunks

posterior divisions of the upper, middle, and lower trunks

These six Divisions will regroup to become the three Cords. The Cords are named by their position to the axillary artery.

The Posterior Cord is formed from the three posterior divisions of the trunks (C5-C8, T1)

The Lateral Cord is the anterior divisions from the upper and middle trunks (C5-C7)

The Medial Cord is simply a continuation of the anterior division of the lower trunk (C8, T1)

 

Anatomical illustration of the brachial plexus with areas of roots, trunks, divisions, and cords marked.

Specific Branches

The branches are listed below. They mostly branch from the cords, but some originate from earlier structures.

 

From NerveRoots

rootsDorsal scapular nerveC4, C5Rhomboid muscles and Levator scapulae-

rootsLong thoracic nerveC5, C6, C7Serratus anterior-

upper trunkNerve to the subclaviusC5, C6Subclavius muscle-

upper trunkSuprascapular nerveC5, C6Supraspinatus and Infraspinatus-

lateral cordLateral pectoral nerveC5, C6, C7Pectoralis major and Pectoralis minor (by communicating with the Medial pectoral nerve)-

lateral cordMusculocutaneous nerveC5, C6, C7Coracobrachialis, Brachialis and Biceps brachiibecomes the Lateral cutaneous nerve of the forearm

lateral cordlateral root of the Median nerveC6, C7fibres to the median nerve-

posterior cordUpper subscapular nerveC5, C6Subscapularis (upper part)-

posterior cordThoracodorsal nerve (middle subscapular nerve)C6, C7, C8Latissimus dorsi-

posterior cordLower subscapular nerveC5, C6subscapularis (lower part ) and Teres major-

posterior cordAxillary nerveC5, C6anterior branch: deltoid and a small area of overlying skin posterior branch: Teres minor and deltoid musclesposterior branch becomes Upper lateral cutaneous nerve of the arm

posterior cordRadial nerveC5, C6, C7, C8, T1Triceps brachii, Supinator, Anconeus, the extensor muscles of the Forearm, and Brachioradialisskin of the posterior arm as the Posterior cutaneous nerve of the arm

medial cordMedial pectoral nerveC8, T1Pectoralis major and Pectoralis minor-

medial cordmedial root of the Median nerveC8, T1fibres to the median nerveportions of hand not served by ulnar or radial

medial cordMedial cutaneous nerve of the armC8, T1-front and medial skin of the Arm

medial cordMedial cutaneous nerve of the forearmC8, T1-medial skin of the forearm

medial cord, Ulnar nerveC8, T1Flexor carpi ulnaris, the medial two bellies of Flexor digitorum profundus, the intrinsic hand muscles except the Thenar muscles and the two most lateral lumbricalsthe skin of the medial side of the hand and medial one and a half fingers on the palmar side and medial two and a half fingers on the dorsal side.

 

Injuries

Injury to the brachial plexus can be very problematic because the nerves branching off of the plexus provide innervation to the upper extremity. Clinical signs and symptoms vary with which area of the plexus is involved, and generally result in paralysis or anesthesia.

 

Symptoms can range from transient nerve dysfunction to complete upper extremity weakness. Because of the anatomical variants[5] of the brachial plexus these injuries can be a challenge to diagnose.

 

Mechanism of Injury

The main causes of brachial plexus palsies are traction, due to extreme movements, and heavy impact. 

 

Brachial plexus injury can occur in a variety of ways and can occur as a result of shoulder trauma, tumours, or inflammation. The rare Parsonage-Turner Syndromec brachial plexus inflammation without obvious injury, but with nevertheless disabling symptoms. But in general, brachial plexus lesions can be classified as either traumatic or obstetric.

 

Obstetric injuries may occur from a mechanical injury involving shoulder dystocia during a difficult childbirth. During birth, excessive stretching of the neck or pulling the upper extremity can result in an upper brachial plexus injury or inferior trunk, respectively. The incidence of brachial plexus injury is approximately 1 in 1,000 live births.

Traumatic injury may arise from penetrating or sports-related injuries, falls, work-related injuries, radiation therapy and iatrogenic causes (i.e. first rib resection, shoulder surgery, brachial plexus block).

However the most common mechanism of injury is a traction injury due to the forceful separation of the neck from the shoulder.

Common associated injuries can include fractures of the proximal humerus, clavicle, scapula, cervical spine and upper limb vascular injuries. Management of these injuries may complicate the picture when diagnosing brachial plexus injury but can also guide in determining the mechanism of injury.

 

 

Classification of Injury

There are many classification systems for brachial plexus injuries, they can be divided into three types:

 

An upper brachial plexus lesion, which occurs from excessive lateral neck flexion away from the shoulder. Most commonly, forceps delivery or falling on the neck at an angle causes upper plexus lesions leading to Erb's Palsy. This type of injury produces a very characteristic sign called Waiter's tip deformity due to loss of the lateral rotators of the shoulder, arm flexors, and hand extensor muscles.

Less frequently, the whole brachial plexus lesion occurs.

Most infrequently, sudden upward pulling on an abducted arm (as when someone breaks a fall by grasping a tree branch) produces a lower brachial plexus lesion, in which the eighth cervical (C8) and first thoracic (T1) nerves are injured either before or after they have joined to form the lower trunk. The subsequent paralysis affects the intrinsic muscles of the hand and the flexors of the wrist and fingers.This results in a form of paralysis known as Klumpke's Paralysis.

However, a commonly used one is Leffert's classification system which is based on etiology and level of injury:

 

I Open (usually from stabbing)

II Closed (usually from a motorcycle accident)

IIa Supraclavicular (preganglionic or postganglionic)

IIb Infraclavicular

IIc Combined

III Radiation-induced

IV Obstetric

IVa Erb's (upper root)

IVb Klumpke (lower root)

IVc Mixed

Signs and Symptoms

Nerve damage causes a multifaceted clinical picture consisting of sensorimotor disturbances (pain, muscle atrophy, muscle weakness, secondary deformities) as well as the reorganisation of the Central Nervous System that may be associated with upper limb underuse.

 

Pain is most common, in particular, those affecting the preganglionic fibres. Often described as crushing with intermittent severe attacks shooting down the arm.

Paralysis and anaesthesiain affected extremity.

Bizarre sensations, hyperalgesia, dysesthesia, and allodynia.

Myoclonic jerks in the affected extremity.

Ipsilateral Horners Syndromewith T1 injury.

Investigations

Xray of the shoulder area and cervical spine to determine if any boney abnormalities are causing the lesion.

MRI will help to visualise causative pathology such as tumors, neuritis, radiation injury.

EMG and NCS help to confirm a diagnosis, localise the lesion and determine the degree of axonal loss. These tests are the most useful tests to determine localisation of the plexopathy, especially, the sensory nerve conduction studies (SCSs) because sensory nerve action potential amplitude will decrease in plexopathies due to Wallerian degeneration of the postganglionic sensory fibers.

Histamine test to differentiate between pre and postganglionic lesion.

Management

brachial plexus injury may result in severe and chronic impairments in both adults and children, thus requiring early and long-lasting treatment. 

 

Medical Management

The main aspect of medical management is pain control. Often treated in a similar way to neuropathic pain with NSAID, tricyclic antidepressants, anticonvulsants, and oral or transdermal opioids.

Psychological Management

Psychological problems and a lack of cooperation by the patient may limit rehabilitation effects and increase disability.

Physiotherapy Management

See also Brachial Pluxus Injury for Physiotherapy Management

 

The aim is to maintain the range of motion of the extremity, to strengthen the remaining functional muscles, to protect the denervated dermatomes, and to manage pain.

 

Pain control - acupuncture, TENS

Maintaining ROM - passive movements,exercise therapy, splinting, positioning

Strengthen affected muscles - biofeedback, exercise therapy

Managing chronic oedema - compression garments, advice, massage therapy

Intervention Management

Continuous brachial plexus block

Transcutaneous nerve stimulation

Dorsal route entry zone (DREZ) ablation or implantable dorsal route stimulators.

Surgical techniques include neurolysis, nerve grafting, and nerve transfer. Intercostal nerves are commonly used to reinnervate muscles after a brachial plexus injury with avulsion of spinal nerve roots.

Brachial Plexus Block

A brachial plexus block allows a surgeon to operate on an upper extremity without the use of a general anesthetic, when combined with a tourniquet.

 

The location of the injection is between the posterior border of the sternocleidomastoid and the clavicle. The axillary sheath surrounds the axillary vein, axillary artery, and three cords of the brachial plexus. When the injection takes effect, the muscles and skin innervated by the cords found in the sheath are anesthetized. 

 

Other Information

Some mnemonics for remembering the branches:

 

Posterior Cord Branches

STAR - subscapular (upper and lower), thoracodorsal, axillary, radial

ULTRA - upper subscapular, lower subscapular, thoracodorsal, radial, axillary

Lateral Cord Branches

LLM "Lucy Loves Me" - the lateral pectoral, lateral root of the median nerve, musculocutaneous

Medial Cord Branches

MMMUM "Most Medical Men Use Morphine" - medial pectoral, medial cutaneous nerve of arm, medial cutaneous nerve of forearm, ulnar, the medial root of the median nerve.


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