A neurological syndrome of unknown cause was identified as a potential novel degenerative disease in a cluster of individuals with similar clinical signs and symptoms in the Canadian province of New Brunswick beginning in 2019. Symptoms listed on the New Brunswick Public Health (NBPH) website include memory problems, muscle spasms, balance problems, difficulty walking or falls, blurred vision or visual hallucinations, unexplained or significant weight loss, behaviour changes, and pain in the upper or lower limbs.
Background
The investigation into the cluster was instigated in 2019 at the federal level by the Ottawa-based Creutzfeldt-Jakob Disease Surveillance System (CJDSS) unit – which operates under Public Health Agency of Canada (PHAC). CJDSS director Michael Coulthart worked with Alier Marrero, a neurologist at Dr. Georges-L.-Dumont University Hospital Centre, in Moncton, New Brunswick who had referred cases to the CJDSS unit for testing and diagnosis. The disease cluster was first noted through the routine case management arrangement between New Brunswick and federal health authorities, when experts from the CJDSS unit – which provides surveillance for "all types of human prion disease in Canada" – noticed a significant number of NB referrals had "some common symptoms and similar potential diagnostic profiles". The CJDSS ruled out any prion disorder, including Creutzfeldt-Jakob Disease (CJD) – an incurable, fatal disease. Marrero and Coulthart and colleagues worked for months together investigating the cases. The federal-provincial team began to suspect that they were looking at a novel neurological degenerative disease potentially caused by a toxin or agent. By December 2020, 24 new cases in New Brunswick of something that "looked like CJD but was not" had been diagnosed. PHAC considered this to be an "unusually high number" and contacted New Brunswick's Chief Medical Officer of Health (CMOH) Jennifer Russell, about the disease cluster. In January 2021, the federal-provincial team, which included Coulthart, Marrero, and neuropathologist, Gerard Jansen, drafted the first case definition of the New Brunswick neurological syndrome of unknown cause, and described its symptoms.
In March 2021, provincial health authorities shared information describing symptoms with New Brunswick physicians in a memorandum that was leaked to the media. On 27 April 2021, NBPH published a webpage which is updated to inform the public of the disease cluster, its symptoms, ongoing investigations and their findings.
Symptoms
In a 25 March 2021 interview, Marrero said that initial symptoms are often nonspecific, making a diagnosis challenging. He listed symptoms such as "behavioral changes, sleep disturbances, unexplained pain, visual hallucinations, coordination problems, unexplained hair loss, involuntary muscle twitching, formication (a sensation that feels like small insects crawling under the skin), ataxia, and brain atrophy".
In April the NBPH website listed symptoms such as memory problems, muscle spasms, balance issues, difficulty walking or falls, blurred vision or visual hallucinations, unexplained or significant weight loss, behaviour changes and pain in the upper or lower limbs.
In interviews conducted by the media, patients and their families described symptoms such as rapidly progressing dementia, unexplained and significant weight loss, myoclonus, aphasia, changes in behaviour, sleep disturbances, unexplained pain, visual hallucinations, co-ordination problems and severe muscle and brain atrophy, progressing over a period of 18 to 36 months. The majority experience multi-day insomnia even with "sleep medication". Memory loss and aphasia are seen. In some cases, Capgras delusion and echolalia have been reported. Myoclonus persists "even in the late stages of the disease" and even "when patients are unconscious". Akinetic mutism were observed in late-stage patients, where they no longer have the ability to speak or move. The New York Times reported symptoms of "extreme fatigue, involuntary jerking movements, memory lapses and hallucinations" on 4 June 2021.
Demographics
The cases indicate that the disease affects men and women equally. It affects all age groups, with a median age of patients being 40 years old. Patients have been as young as 18 to as old as 85 or 86.
Etiology
The working name used by investigators to the disease was "neurological syndrome of unknown etiology in New Brunswick". The CMOH referred to it as progressive neurological syndrome of unknown cause", and it is now called "neurological syndrome of unknown cause" on the NBPH website.