Here’s a deeper look at ALS, with background information gleaned from the ALS Association website and a Bay Area News Group feature on the disease.
How ALS affects afflicted
It severely hinders motor function, making such activities as moving, eating and breathing difficult.
The degenerative affliction is a progressive weakening of the muscles caused by nerve degeneration. Early symptoms include weakness in the arms or legs, slurred speech and trouble chewing and swallowing. Over time, muscles stop responding.
The disease does not affect the heart, but it does attack the respiratory system. ALS patients often die of pneumonia.
The disease commonly is diagnosed about two years after symptoms begin and 50 percent of patients die within three to five years of diagnosis. Twenty percent live five years or more and up to 10 percent will live more than 10 years.
How ALS is diagnosed
There is no one test or procedure to establish a diagnosis of ALS. A series of clinical exams and diagnostic tests rule out other diseases that mimic ALS — like a B-12 deficiency with which Clark was diagnosed.
Some of the examinations and tests include electomyography (EMG), nerve conduction velocity (NCV) and blood and urine samples. Thyroid hormone levels are among those checked.
A spinal tap and MRI can also be used in the diagnosis, as can a myelogram of the cervical spine and a muscle and/or nerve biopsy.
Who has ALS?
An estimated 20,000 people in the U.S are living with ALS at any given time. About 6,000 people in the U.S. are diagnosed with the disorder each year.
Former Saints safety Steve Gleason went public with his diagnosis and eventually starred in a movie called Gleason about the experience of living with ALS.
|AP Photo/Bob Gabraith Former 49ers vice president Dwight Clark attends a news conference in 1998, By DANIEL MANO|
Former 49ers WR Clark reveals he has ALS
SAN FRANCISCO — Dwight Clark revealed Sunday that he has Lou Gehrig's disease and suspects playing football might have caused the illness.
Clark announced on Twitter that he has amyotrophic lateral sclerosis, a disease that attacks cells that control muscles. The former San Francisco 49ers wide receiver linked to a post on his personal blog detailing his ALS diagnosis, but the site crashed Sunday night, apparently from an overflow of traffic.
"I've been asked if playing football caused this," Clark said in the post. "I don't know for sure. But I certainly suspect it did."
The 60-year-old Clark wrote that he began experiencing symptoms in September 2015. He's lost significant strength in his left hand and also has weakness in his right hand, midsection, lower back and right leg.
"I can't run, play golf or walk any distances," he said. "Picking up anything over 30 pounds is a chore. The one piece of good news is that the disease seems to be progressing more slowly than in some patients."
Clark won two Super Bowls with the 49ers during a nine-year career that ended in 1987. He memorably pulled down the winning touchdown pass from Joe Montana in the 1981 NFC Championship Game against the Dallas Cowboys, a play remembered simply as "The Catch."
Clark, whose No. 87 has been retired by the 49ers, also encouraged the NFL and the players' association to work together in making football safer.
San Francisco CEO Jed York said in a statement he was "deeply saddened" by Clark's diagnosis.
"Many know Dwight as an iconic figure in 49ers lore, whose accomplishments on the field brought joy to fans around the world," York said. "Our organization is fortunate to know him more intimately as a wonderful man who has given so much of himself as an ambassador to the entire Bay Area. We will stand alongside Dwight and his family as they wage this battle."
After his playing career ended, Clark served as general manager of the 49ers and Cleveland Browns.