Normal F wave responses
These are examples of normal F-wave responses from 73 healthy individuals.
Nerve Site value (msec)
Median wrist 28
Ulnar wrist 29
Peroneal ankle 54
Tibial ankle 55
Alavian-Ghavanini MR and Haqhpanah S.
Electromyogr Clin Neurophysiol 2000 Sept 40(6): 375-9
The posterior cruciate ligament (PCL) prevents the tibia (shin bone) from moving backwards relative to the femur (thigh bone). Injuries to this ligament tend to occur when the knee is bent and the upper leg moves forwards relative to the lower leg, such as when it collides with a car dashboard or a person.
Injury to this structure may not cause many symptoms. There may be pain in the back of the knee with squatting or kneeling, a slight limp, or loss of the full range of knee flexion. With chronic injury to the PCL, there may be problems using stairs or ramps.
The principles of therapy are rest, ice, compression, elevation, medications and protection. Often crutches are recommended if weight bearing causes pain, but otherwise crutches are not necessary. Return to light duty activity is ok soon after an injury.
Most PCL injuries do not occur by themselves. They are often associated with meniscus injuries or other trauma to the knee. They are also difficult to distinguish from other ligament injuries to the knee. When the PCL is injured, there is often no pop sensation, just a vague feeling of discomfort.
Very rarely, people with hypothyroidism develop a painful condition of the muscles. This condition, myotonia, results in pain, cramping, and weakness. It may affect the proximal muscles of the arms or the legs.
In these conditions, a peculiar exam finding may be made. Tapping the muscle with a reflex hammer can cause a ridge of muscle contraction, referred to as myoedema. In some cases, thickening of the muscles occurs due to fluid retention or the deposition of connective tissue.
Treatment of hypothyroidism with thyroid supplements is normally helpful for thyroid-related muscle diseases.
Other illnesses that may affect the muscles include:
Adrenal gland, pituitary gland, parathyroid gland problems, exposure to toxins or certain medicines, and diseases of nutrition or metabolism
The meniscus is a piece of cartilage in the knee. It looks like a contact lens holder, a pair of cups facing up at the top of the lower leg, where the bony prominences of the upper leg bone (femur) slide back and forth. The meniscus can be injured when the knee is twisted or bent, in particular when the knee is flexed. Injuries to the meniscus are common in people who play sports such as soccer, basketball and football, but they can occur in anyone who twists their knee.
When the meniscus is injured, there is often swelling, pain, and decreased range of motion.
Treatment of the injured meniscus is best with the following:
Avoid positions and activities that irritate the knee, such as kneeling, squatting, twisting, or taking steps.
Elevation of the leg
Ice packs to the knee to reduce swelling and soreness
Using crutches if the pain is severe
Using a brace if the knee is unstable
As the pain improves, straight leg raising without resistance is recommended, as well as working with a physical therapist.
MRI studies and possibly a referral to orthopedic surgery are recommended when the above treatments are not helpful, or when the range of motion of the knee does not recover.
Sometimes a meniscus injury occurs with minimal trauma. This tends to happen in people who are older. Normally physical therapy is sufficient for improving this condition, and surgery is not needed.
Tinnitus is an abnormal sound that we hear. Tinnitus is caused by a disruption of the sound sense, anywhere from the brain to the cochlea. It may be a hum, ring, roar, whoosh, click or other sound. Normally tinnitus can be heard only by the person who has this condition. There are many possible causes of tinnitus.
A spasm of a muscle in the inner ear
An injury to the cochlea, the organ that conducts hearing
The sound of blood passing through a nearby blood vessel, especially a deformed blood vessel
Increases in the pressure inside the head
Clicking noises can arise from the muscles of the palate
Ocean-like noises can arise from the eustachian tube
Medicine side effects – some medicines are toxic to the inner ear
Small tumors of the acoustic nerve
50 million people in the US have chronic tinnitus, which is a sound symptom lasting longer than 5 months. People with tinnitus may experience symptoms of anxiety or depression. Trouble sleeping is often associated with tinnitus.
Testing that is important for evaluating the causes of tinnitus.
MRI or CT studies to look at the blood vessels
Exam by an ENT specialist
Splinting for carpal tunnel syndrome is often effective for mild cases. Splinting regimens for 24 / 7 or just while sleeping have both been shown to be helpful.
There are several forms of carpal tunnel wrist splints available, from simple generic versions to custom fitted models. Make sure the one you use is comfortable.
PFO and stroke
PFO is a patent foramen ovale, a small hole connecting the atria chambers of the heart. A PFO is found in about 25% of people.
Many cases of stroke are not explained, and are therefore labeled as cryptogenic stroke. This means they are not found to be associated with narrowing of the cerebral arteries, abnormal heart rhythm, high cholesterol, smoking or high blood pressure.
It has been attractive to consider whether having a PFO increases the risk of stroke. Perhaps a blood clot forms in a low flow vein, after a long plane trip. It finds its way back to heart, with the other venous blood, then crosses the PFO, into the arterial system, and makes its way directly to the brain? This mechanism of stroke is often speculated, but rarely proven.
Following most cases of stroke, patients are treated with antiplatelet medicines aspirin or Plavix to prevent a future stroke. Studies have shown that patients treated with anticoagulation medicine or surgical PFO closure have not had better stroke prevention than patients treated with aspirin. Although other studies are in progress, the results we have to date support the idea that most PFOs are not relevant to stroke risk.
Carroll JD et al. RESPECT Investigators. Closure of patent foramen ovale versus medical therapy after cryptogenic stroke. N Engl J Med 2013;368:1092–1100.
Furlan AJ et al. CLOSURE I Investigators. Closure or medical therapy for cryptogenic stroke with patent foramen ovale. N Engl J Med 2012;366:991–999.
Homma S et al. ; PFO in Cryptogenic Stroke Study (PICSS) Investigators.Effect of medical treatment in stroke patients with patent foramen ovale: Patent Foramen Ovale in Cryptogenic Stroke Study.Circulation 2002;105:2625–2631.
Meier B et al. PC Trial Investigators. Percutaneous closure of patent foramen ovale in cryptogenic embolism. N Engl J Med 2013;368:1083–1091
Shariat A et al. . Comparison of medical treatments in cryptogenic stroke patients with patent foramen ovale: a randomized clinical trial. J Res Med Sci 2013;18:94–98
Ocrelizumab is a medicine designed to treat multiple sclerosis. It is indicated for relapsing remitting MS (RRMS) and primary progressive MS (PPMS). It is made by Genentech.
Ocrelizumab is given by the IV route, 600 mg every 6 months. The retail cost of the medication is $65000 per year.
Ocrelizumab is an anti CD20 antibody. It reduces the number of B lymphocytes in the immune system. It is similar to an older medicine named rituximab.
Clinical trial results
In 480 patients with PPMS treated with ocrelizumab, progression of PPMS was slowed by 24%. This was assessed over 96 weeks.
For 800 patients with RRMS treated with ocrelizumab, there was a significant reduction in relapses in over 96 weeks. Patients treated with ocrelizumab had a 46% reduction in relapses compared to those treated with beta interferon 1a. About half of the patients had no relapses or new MRI lesions while using ocrelizumab.
Side effects of ocrelizumab are generally reported as mild. They include infusion site reactions, headache, back pain, fatigue, influenza, upper respiratory tract infection, or depression.
Ocrelizumab should not be used in patients with hepatitis B or other infections. Ocrelizumab may be associated with a higher rate of new malignancies (cancers) compared to interferon.
Hauser SL, et al. New Eng J Med. 2017 Jan 19 276(3): 221-234
Montalban X, et al. New Eng J Med. 2017 Jan 19 376(3): 209-220
PCOS is a condition that affects women, often during teenage or young adult years. This condition is associated with increased weight, acne, irregular periods, or unwanted hair growth. The symptoms of this condition are related to hormone function.
People with PCOS should have a menstrual abnormality for 2 years or more. This may be irregular frequency of periods, such as no period for 90 or more days, or a later age of the first period, for example. Many people with PCOS have increased body weight, male pattern hair growth, high blood sugar or difficult to control acne symptoms.
There are several conditions that are similar to PCOS. These are normally related to other hormone conditions, such as those that affect the thyroid, cortisol, growth hormone, or prolactin hormone functions.
PCOS can be diagnosed with a clinical exam and history, an ultrasound test of the ovaries, and tests for hormone levels such as testosterone, hCG, TSH, and FSH. When the diagnosis is made, evaluation of sleep disorders, glucose level, cholesterol and heart function are often considered.
Women may have problems having a pregnancy for a variety of reasons. These include:
Body weight far above or below the ideal level
Women who are very thin or very overweight may observe irregularity of their menstrual cycle. This has an effect on the success of pregnancy, since differences in weight may affect hormone production. Women who exercise a lot may have similar symptoms. Some women who are overweight have polycystic ovarian syndrome, a condition that affects egg production and influences body weight.
Changes in hormones that are needed to regulate the monthly cycle
Some women with infertility may have problems making hormones necessary for pregnancy, such as prolactin, FSH or LH. These hormones can be measured by blood tests, and treatments to replace or influence these hormones levels may be helpful.
Changes in the structures of the fallopian tubes or uterus
A variety of factors can affect the structure of the uterus or the fallopian tubes. The fallopian tubes are necessary to deliver eggs from the ovary to the uterus, where fertilization and implantation occur. Fallopian tubes can be affected by conditions like endometriosis or pelvic inflammatory disease. The uterus can be affected by these causes as well as fibroids, the uterus structure, or other factors.
Treatments for infertility depend on the cause. Sometimes specialized treatments are helpful for infertility. These may be stimulation of egg production with a medicine like clomid, in vitro fertilization, or selection of eggs and sperm with normal genetic material to facilitate a healthy pregnancy.