Numbness, Tingling, and Altered Sensation

Introduction

Numbness, tingling, and altered sensation are common presenting symptoms in Canadian primary care and emergency settings. As a future Canadian physician preparing for the MCCQE1, it's crucial to understand these symptoms' underlying causes, diagnostic approaches, and management strategies within the context of the Canadian healthcare system.

Pathophysiology

Understanding the pathophysiology of numbness, tingling, and altered sensation is essential for MCCQE1 success. These symptoms often result from disruptions in the somatosensory system, which can occur at various levels:

1. Peripheral nerves
2. Nerve roots
3. Spinal cord
4. Brain

Common Causes in Canadian Population

For MCCQE1 preparation, focus on these prevalent causes of numbness, tingling, and altered sensation in the Canadian population:

1. Diabetic Neuropathy: With diabetes affecting approximately 3.4 million Canadians, diabetic neuropathy is a significant cause of sensory symptoms.

2. Carpal Tunnel Syndrome: Common in office workers and manual laborers, affecting up to 3% of Canadians.

3. Multiple Sclerosis: Canada has one of the highest rates of MS globally, with 1 in 385 Canadians affected.

4. Vitamin B12 Deficiency: More common in older adults and those following plant-based diets.

5. Cervical Radiculopathy: Often seen in middle-aged adults due to degenerative changes.

6. Stroke: A leading cause of neurological deficits in Canada, with about 62,000 strokes occurring annually.

Diagnostic Approach

When preparing for the MCCQE1, focus on mastering this step-wise diagnostic approach:

Canadian Guidelines for Management

The Canadian Neurological Sciences Federation (CNSF) provides guidelines for managing various neurological conditions. Key points for MCCQE1 preparation include:

1. Diabetic Neuropathy:

   • Optimize glycemic control (target HbA1c <7%)
   • Consider pregabalin or duloxetine as first-line treatments for painful diabetic neuropathy

2. Carpal Tunnel Syndrome:

   • Conservative management with wrist splinting and activity modification
   • Surgical decompression for severe or refractory cases

3. Multiple Sclerosis:

   • Early initiation of disease-modifying therapies
   • Multidisciplinary approach involving neurology, physiotherapy, and occupational therapy

4. Vitamin B12 Deficiency:

   • Oral supplementation (1000-2000 mcg daily) for most cases
   • Intramuscular injections for severe deficiency or malabsorption

5. Stroke:

   • Rapid assessment and thrombolysis within 4.5 hours of symptom onset, if indicated
   • Implementation of stroke units for comprehensive care

Key Points to Remember for MCCQE1

• Understand the anatomical basis of sensory symptoms and their correlation with specific lesion locations
• Recognize the high prevalence of multiple sclerosis in Canada and its varied presentations
• Be familiar with the Canadian Diabetes Association guidelines for managing diabetic neuropathy
• Know the indications for urgent neuroimaging in patients presenting with sensory symptoms
• Understand the role of electrophysiological studies in diagnosing peripheral nerve disorders
• Be aware of the Canadian Stroke Best Practice Recommendations for acute stroke management
• Recognize the importance of occupational factors in conditions like carpal tunnel syndrome

Sample Question

# Sample Question

A 45-year-old woman presents to her family physician with a 3-month history of numbness and tingling in her right hand, particularly affecting her thumb, index, and middle fingers. The symptoms worsen at night and when driving. She works as a data entry clerk and spends long hours typing. Physical examination reveals a positive Tinel's sign at the right wrist. Which one of the following is the most appropriate next step in management?

- [ ] A. Order an MRI of the cervical spine
- [ ] B. Prescribe pregabalin for symptom relief
- [ ] C. Recommend wrist splinting and ergonomic modifications
- [ ] D. Refer for immediate carpal tunnel release surgery
- [ ] E. Start a course of oral corticosteroids

Explanation

The correct answer is:

• C. Recommend wrist splinting and ergonomic modifications

This patient's presentation is classic for carpal tunnel syndrome (CTS), a common condition in Canada, especially among office workers. The symptoms of numbness and tingling in the median nerve distribution (thumb, index, and middle fingers), worsening at night, and the positive Tinel's sign are all consistent with CTS.

According to Canadian guidelines, the initial management of CTS should be conservative, focusing on:

1. Wrist splinting, especially at night
2. Ergonomic modifications to reduce wrist strain
3. Activity modification and breaks during repetitive tasks

These conservative measures are often effective and should be tried before considering more invasive options. Surgery (option D) is reserved for severe or refractory cases and would not be the most appropriate first step.

Other options are less appropriate:

• A: An MRI of the cervical spine is not indicated as the first step, given the localized symptoms and positive Tinel's sign suggesting CTS.
• B: Pregabalin is not a first-line treatment for CTS and is more commonly used for neuropathic pain conditions.
• E: Oral corticosteroids are not routinely recommended as initial therapy for CTS in Canadian practice.

References

1. Boulton, A. J. M., et al. (2020). Diabetic Neuropathies: A Position Statement by the American Diabetes Association. Diabetes Care, 43(7), 1617-1628.

2. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. (2018). Canadian Diabetes Association 2018 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. Can J Diabetes, 42(Suppl 1), S1-S325.

3. Derry, S., et al. (2019). Pregabalin for neuropathic pain in adults. Cochrane Database of Systematic Reviews, 1(1), CD007076.

4. Graham, R. (2016). Canadian Best Practice Recommendations for Stroke Care. Canadian Stroke Network.

5. Keith, M. W., et al. (2009). American Academy of Orthopaedic Surgeons Clinical Practice Guideline on the Treatment of Carpal Tunnel Syndrome. J Bone Joint Surg Am, 91(1), 218-219.

6. Multiple Sclerosis Society of Canada. (2021). About MS. Retrieved from https://mssociety.ca/about-ms (opens in a new tab)

7. Wein, T., et al. (2018). Canadian stroke best practice recommendations: Secondary prevention of stroke, sixth edition practice guidelines, update 2017. International Journal of Stroke, 13(4), 420-443.