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Neurologic Pathologies of the Hand Melinda McMillen: Jordan Utley & Jenn Ostrowski Section 1 Introduction to the Pathology Incidence of the Pathology There are numerous neurologic pathologies involving the hand and the most common of these are nerve compression syndromes. The most prevalent of these conditions include carpal tunnel syndrome (CTS), ulnar neuropathy (UN), and radial tunnel syndrome (RTS) involving the median, ulnar, and radial nerves respectively. CTS is often seen in women between ages 30 and 50. UN is less common than CTS and is frequently seen in baseball pitchers (Steinberg, 2012). Signs and symptoms of different types of neuropathy are seen in 20% of all diabetic patients (Weisberg, Garcia, Strub). Etiology Compression of the nerves can result from trauma, disease or compression by surrounding tissues and can happen anywhere along the nerves path from spinal cord down the arm. Predisposing factors for nerve compression syndromes in the hand include pregnancy, rheumatoid arthritis, diabetes, alcoholism, renal failure and genetic defects (Weisberg, Garcia, Strub). Carpal tunnel syndrome can be caused by activities or jobs where repetitive flexion and extension of the wrist is regular. Most cases are idiopathic. In cubital tunnel syndrome the entrapment of the ulnar nerve occurs at the elbow and is most often caused by leaning on the elbow or by excessive elbow flexion. In cases of radial tunnel syndrome the more likely MOI is constant use of the arm and repetitive motion of the elbow and wrist such as twisting, gripping, pushing and pulling can stretch and irritate the radial nerve (Steinberg, 2012). <Photo 1: Etiology> Section 2 Anatomy & Physiology of the Injury Anatomy The three peripheral nerves that provide motor and sensory input to the hand are the median, ulnar and radial nerves. Median Nerve The median nerve is a branch of the medial and lateral cords of the brachial plexus. It follows the flexor digitorum superficialis muscle down the forearm and travels through the lateral side of the carpal tunnel in the wrist. Then it splits into motor and palmar branches. It provides sensation to the thumb, index, middle and half of the 4th finger and provides the ability to grasp an object with the thumb and forefinger. Ulnar nerve The ulnar nerve is a branch of the medial cord of the brachial plexus. This nerve is superficial and travels on the medial palmar aspect of the wrist as it passes through the Tunnel of Guyon, which is formed by the pisiform and hamate carpal bones. In the hand it divides into a superficial and deep branch. This nerve innervates the little finger and half of the ring finger and allows wrist and finger flexion. Radial nerve The radial nerve is a branch of the posterior cord of the brachial plexus. The nerve runs along the lateral side of the elbow where the nerve passes into the radial tunnel, formed by muscles and bone. Passing through the tunnel the radial nerve runs below the supinator muscle where is divides into the superficial and deep branches. The superficial branch provides sensation to the skin on the dorsal aspect of the hand while the deep branch allows wrist and finger extension (Starkey, Brown, Ryan, 2010, pg 761)(Peripheral Nerve System). <Photo 2: Anatomy> <Photo 3: Anatomy> Physiology Nerve compression syndromes, as the name suggests, are caused by the nerve becoming compressed by surrounding tissues other than a problem with the nerve itself. The nerves innervating the hand can become entrapped many different ways and each is specific to the individual nerve. The median nerve is often compressed as it passes beneath the transverse carpal ligament. This can be from inflammation, repetitive motions or genetically smaller tunnels in the wrist (Weisberg, Garcia, Strub). The ulnar nerve is most likely compressed at the elbow causing cubital tunnel syndrome but can also be injured in the wrist at the Tunnel of Guyon by the pisiform and hamate. These bones, with repetitive actions and superficial placement, can compress the ulnar nerve (Guardia at al, 2013). The radial nerve can be entrapped at the elbow as it twists around the humerus. This can cause weakness in the wrist and cause drop wrist syndrome. The extensor muscles in the hand are not able to function causing the hand to stay in a “dropped” position (Weisberg, Garcia, Strub). <Photo 4: Physiology> Section 3 Evaluation of the Injury Signs and Symptoms The most common symptom in nerve pathologies in the hands is paresthesias, which is a prickly, tingling sensation. The location of the symptoms will correlate with the specific nerve that is being entrapped. This will, also, be consistent with muscle weakness. For example, if the radial nerve is involved the patient will present with difficulty extending the wrist (Steinberg, 2012). <Photo 5: Signs and Symptoms> Special Tests: Defining Practice Evaluation Tinel’s sign is the preferred special test for all three nerve pathologies. It is performed by tapping over the nerve to reproduce the paresthesia symptoms. Phalen’s test is also used for suspected carpal tunnel. This is performed by the patient flexing both wrist and pushing the dorsal side of the hands together in front of their chest and holding this for one minute. The most important information is found while taking a patient history. This will pinpoint the exact location of the symptoms, which will clarify which nerve is involved. For example numbness in the dorsal aspect of the hand is indicative of ulnar nerve entrapment at the elbow when numbness on the palmar aspect of the hand indicates impingement at the Tunnel of Guyon. An accurate history will, also, indicating if any trauma or accident caused the symptoms. This is important because tingling and pain in the hands can also be brought on by injury to the upper arm or the cervical spine and a further examination is needed in such cases (Starkey, Brown, Ryan, 2010 pg 784, 805). <Photo 6: Phalen’s test> <Photo 7: Tinel’s test> <Video 1: Tinel’s sign> Section 4 Associated differential diagnoses Because the structures of the wrist and hand are so close together it is critical to obtain enough details in the history and examination to know the exact location of symptoms. All three nerves that innervate the hand travel down the full length of the arm and can become entrapped at anytime. Most commonly at the elbow and wrist. Even though it is the same nerve and may have similar symptoms they are two different diagnosis and treatments whether the nerve is compressed at the elbow or wrist. There can be many types of differential diagnoses and that is why taking an accurate history is crucial. One example is radial tunnel syndrome at the wrist and elbow may present similarly but are treated differently and it is paramount in differentiating between the two by noticing if the pain radiates up the forearm then the nerve is compressed at the elbow. Another example is cubital tunnel syndrome and ulnar nerve compression. They both affect the ulnar nerve but the first is located at the elbow and the later at the wrist. They are differentiated by the presence of sensory deficits just on the dorsal aspect of the hand or if they are present proximal to the wrist as well (Steinberg, 2012). Section 5 Prognosis & Recent Evidence Informing Best Clinical Care Prognosis Prognosis is improved the sooner treatment is started once the symptoms appear. If 6 months of conservative treatment such as rest, splints and anti-inflammatory does not alleviate pain or if muscle weakness is severe, surgery is recommended. Specifically considering carpal tunnel syndrome recurrence following surgery is rare. The majority of patients experience a full recovery (Carpal Tunnel Syndrome Fact Sheet, 2013). <Photo 8: Prognosis> Recent Research A case study published 2013 in Journal of Surgical Case Reports gives detail into something that has not been published before. It is titled “Ulnar nerve compression in Guyon’s canal: MRI does not always have the answer”. The authors explained they had a patient who presented with all the symptoms of ulnar nerve compression in his wrist but the MRI imaging was inconclusive. Lipoma in the Tunnel of Guyon is rare and in their literature search they only found 6 case studies. In all of the articles “surgical excision of the lipoma led to good relief of ulnar nerve symtoms”. They believed in “treating the patient not the scan” so they decided to perform surgery and found a lipoma in the canal and removed it leading to positive results as the previous case studies. Paget, James., Patel, Neil., Manushakian, Jacob. (2013). Ulnar nerve compression in Guyon’s canal: MRI does not always have the answer. Journal of Surgical Case Reports. Retrieved June 22, 2013, from http://jscr.oxfordjournals.org/content/2013/1/rjs043.full.pdf+html References Carpal Tunnel Syndrome Fact Sheet. (June, 2013). National Institute of Neurological Disorders and Stroke. Retrieved June 22, 2013, from http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm Guardia, Charles F III, MD et al. (February 2013). Ulnar Neuropathy. Retrieved June 21, 2013, from http://emedicine.medscape.com/article/1141515-overview#a0101 Peripheral Nerve System. John Hopkins Medicine. Retrieved June 21, 2013, from http://www.hopkinsmedicine.org/neurology_neurosurgery/specialty_areas /peripheral_nerve_surgery/conditions/peripheral_nerve_system.html Starkey, C., Brown, S., Ryan, J. (2010). Examination of Orthopedic and Athletic Injuries (3rd ed.). Philidelphia, PA: F.A. Davis Company. Steinberg, David R. MD. (February 2012). Nerve Compression Syndromes. Retrieved June 21, 2013, from http://www.merckmanuals.com/professional/musculoskeletal_and_connect ive_tissue_disorders/hand_disorders/nerve_compression_syndromes.html Weisberg, LA., Garcia, C., Strub, R. Diseases of the Peripheral Nerves and Motor Neurons. Retrieved June 21, 2013, from http://tulane.edu/som/departments/neurology/programs/clerkship/uploa d/wch16.pdf