General
- Clinical Cornerstone: The physical examination is the traditional cornerstone of medical evaluation and diagnosis.
- Caution with Imaging: Advanced imaging findings do not always correlate with symptomatology in the spine, and relying too heavily on imaging can lead to operations at incorrect levels or for pathologies that are not the patient's main source of symptoms.
Patient History
- Chief Complaint:
- Understanding the patient's priorities (e.g., relief of pain, improved coordination, correction of posture) is crucial,
- Symptom Timing:
- Acute symptoms
- Chronic symptoms.
- Failure to address chronic pain generators (e.g., spondylosis) when treating an acute complaint (e.g., disc herniation) can leave the patient unsatisfied postoperatively.
- Pain Distribution:
- Understanding classic cervical dermatomal distributions is key for diagnosing the offending pathology, especially in multilevel disease.
- C6–7 is the most frequently involved nerve root and is the most variable dermatome, often affecting the index finger and anterior lateral chest.
- C8 symptoms (C7–T1) comprise only about 4%–12% of all cervical cases.
- Subject to variability (especially C7), they are often reliable in the majority of patients.
- Dermatomes of C3–4 and C6–7 have been subject to debate or have not been fully described in the literature.
- Additionally, patients may present with prefixed (C4 contribution) or postfixed (T2 contribution) brachial plexus variants, which requires careful review of imaging to assess for pathology affecting the C4 and T2 roots.
Nerve Root/Segment | Distribution of Pain and Symptoms | Additional Details |
O–C1 | Pain at the base of the skull that worsens with flexion/extension. | Rare occurrence. |
C1–2 | Posterior occiput behind the mastoid. Pain is present with rotating the neck to the left or right. | This condition (Atlantoaxial arthritis) is often missed, but fusion of the C1–2 joint alone can resolve symptoms. |
C2–3 | Pain from the posterior head to the back of the eyes. | ㅤ |
C3–4 | Pain in the upper neck to behind the ear, or paraspinal neck pain. The pain can travel caudally (classic paraspinal neck pain) or be referred cephalad (in addition or instead). | This distribution is incompletely described in most textbooks. |
C4–5 | Pain in the mid-neck to behind the shoulders, sometimes extending into the upper arms. It can be paraspinal and extend up to the bottom of the ears since that is where the trapezius inserts. | ㅤ |
C5–6 | Interscapular pain, lower neck to the radial forearm, thumb, and index finger. | ㅤ |
C6–7 | Affects any single or combination of digits, often including the index finger. It causes symptoms in the anterior lateral chest and axillary regions. | This is the most variable dermatome. It is typically the most frequently involved nerve root. |
C7–T1 (C8 symptoms) | Medial upper extremity. Can also be axillary or across the chest. | C8 symptoms only comprise about 4%–12% of all cervical cases. |
T1–2 | Can be axillary or across the chest. | Herniations at the T1–2 level are frequently missed on axial MRI cuts. |
Pre and postfixed brachial plexus
- Tubbs 2009
- The possibility of prefixed (C4 contribution) or postfixed (T2 contribution) brachial plexus variants must be considered, necessitating careful imaging review for C4 or T2 root pathology.
- Prefixed brachial plexus has been described as having a contribution to the plexus from C4 without a significant contribution from T1
- Incidence of a prefixed plexus: 25% to 48%
- A prefix brachial plexus allows a C5/6 disc causing a c7 radiculopathy.
- Postfixed brachial plexus has been described as having a T2 contribution without a significant contribution from C5.
- Incidence of a postfixed plexus: 2% to 5%.
- intradural interconnections may lead to misinterpretation of spinal levels harboring pathological entities of the spinal axis
- C4 might innervate the deltoid as well
Physical Examination
- Inspection:
- Note prior cervical scars, neck position (e.g., forward protrusion), and check for unilateral atrophy; the dominant arm is typically 1 cm larger in circumference than the non-dominant arm.
- Grip Strength:
- A dynamometer assessment of hand grip strength is useful, as strength decreases with any cervical radiculopathy from C5–T1.
- A dominant arm grip strength that is similar to the non-dominant arm suggests a deficit in the dominant side.
- Reflexes and Myelopathy:
- Check standard reflexes (biceps, triceps, brachioradialis) and look for Hoffman’s or inverted radial reflexes. These signs, indicative of myelopathy, may only be elicited when the neck is flexed or extended (dynamic myelopathy). The jaw jerk reflex should be checked, as a positive finding suggests pathology above the foramen magnum.
- Spurling’s Maneuver:
- This test helps confirm if radiculopathy originates from the neck. Pain replicated by neck movement originates from the neck, while pain from shoulder movement originates from the shoulder.
Myotomes by Daniel Riew
Weak Muscle | Rotator Cuff | Cubital Tunnel | Median N Pronator Teres | C5 | C6 | C7 | C8/T1 |
Deltoid | + | ㅤ | ㅤ | + | ㅤ | ㅤ | ㅤ |
Biceps | ㅤ | ㅤ | ㅤ | + | + | ㅤ | ㅤ |
Triceps | ㅤ | ㅤ | ㅤ | ㅤ | ㅤ | + | ㅤ |
Ex-rotation | + | ㅤ | ㅤ | + | + | ㅤ | ㅤ |
In-rotation | + | ㅤ | ㅤ | ㅤ | ㅤ | ㅤ | ㅤ |
Supination | ㅤ | ㅤ | ㅤ | + | + | ㅤ | ㅤ |
Pronation | ㅤ | ㅤ | + | ㅤ | ㅤ | ㅤ | ㅤ |
Wrist ex | ㅤ | ㅤ | ㅤ | ㅤ | + | ㅤ | ㅤ |
Wrist fl | ㅤ | ㅤ | ㅤ | ㅤ | ㅤ | + | ㅤ |
Finger ex | ㅤ | ㅤ | ㅤ | ㅤ | ㅤ | + | + |
Finger abd | ㅤ | + | ㅤ | ㅤ | ㅤ | ㅤ | + |
Finger add | ㅤ | + | ㅤ | ㅤ | ㅤ | ㅤ | + |
Dynamometer | ㅤ | +/- | ㅤ | + | + | + | + |
APB, Op, FPB, Lat Lum | ㅤ | ㅤ | + | ㅤ | ㅤ | ㅤ | + |
Muscle group | Nerve root |
Deltoid | C5 |
Biceps | C5/6 |
Infraspinatus | C5/6 |
Subscapularis | C5/C6/C7/C8/T1 |
Supinator | C5/6 |
Pronator | C6 |
Wrist extensor | C6 |
Triceps | C7 |
Wrist flexor | C7 |
Extensor digitorum muscle | C7,8 |
Interosseous | C8/T1 |
Opponens | C8/T1 |
Adductor pollicis brevis | C8/T1 |
Flexor pollicis brevis | C8/T1 |
Imaging Scrutiny and Pitfalls
- Correlation: Imaging findings must be carefully correlated with history and physical exam.
- Fusion Diagnosis:
- A fused level is rarely symptomatic.
- Surgeons must diagnose auto-fusions and be vigilant in detecting pseudoarthrosis (failure of fusion).
- Dynamic flexion/extension x-rays are essential for diagnosis of pseudoarthrosis, with less than 1 mm of motion at the arthrodesis level being a key criterion for solid fusion.
- Missed Herniations:
- Fresh, well-hydrated disc herniations in the neuroforamen can be nearly imperceptible on axial MRI; they are easier to diagnose on parasagittal reconstructions.
- Herniations at the T1–2 level are frequently missed because axial cuts often do not include this area, making sagittal images necessary.
- Atlantoaxial Arthritis:
- This is a frequently missed diagnosis that causes pain behind the mastoid process exacerbated by neck rotation.
- Fusion of the C1–2 joint alone can resolve symptoms even if other degenerative levels exist.
- Ossification Conditions:
- Conditions like ossification of the posterior longitudinal ligament (OPLL) should be ruled out, often requiring a CT scan for diagnosis.
- Confirming Reference Cuts:
- Surgeons must verify that the cut lines on the sagittal images accurately reference the corresponding axial images, as mislabeled or erroneous reference lines can lead to operating at the wrong level.
Final Steps in Diagnosis and Treatment
- Differential Diagnosis: Other neurological conditions must be considered, including Parsonage-Turner Syndrome, multiple sclerosis, and amyotrophic lateral sclerosis.
- Diagnostic Injections:
- Injections can aid diagnosis.
- Transforaminal injections are optimal for precise localization, but care is necessary if the patient has a non-normal contralateral vertebral artery.
- Treatment Plan:
- Nonurgent cases begin with nonoperative management (medications, physical therapy, injections).
- Surgery is reserved for patients who fail nonoperative treatment or who have specific indications like moderate/severe myelopathy or recalcitrant radiculopathy.
Differentiating disease
Between C8–T1 radiculopathy vs ulnar neuropathy
General
- C8–T1 radiculopathies (uncommon, 6.2% of cervical radiculopathies)
- Ulnar neuropathy (second most prevalent upper extremity compression syndrome)
- Electromyography (EMG) and nerve conduction studies (NCS)
- can assist in confirming the diagnosis.
- High false-negative rates and suboptimal specificity, especially in diagnosing cervical radiculopathy.
- keep in mind the possibility of anomalous median-ulnar neural pathways, such as a Riche-Cannieu or Martin-Gruber anastomosis, which could alter these canonical motor innervation patterns.
Sensory Differentiation
- Ulnar Neuropathy (at the elbow)
- Sensory distribution
- Medial half of the fourth finger, the entire fifth finger, and the ulnar border of the hand (both palmar and dorsal sides).
- Key differentiator
- Forearm sensation is preserved.
- If an ulnar lesion occurs at the elbow, it would result in anesthesia of the ulnar hand and fingers, but the forearm sensation would remain intact.
- C8–T1 Radiculopathy
- Sensory distribution
- Medial half of the fourth finger, the entire fifth finger, and the ulnar border of the hand (both palmar and dorsal sides).
- Ulnar border of the forearm
- Key differentiator
- The medial antebrachial cutaneous nerve, which supplies the medial forearm, is derived from C8 and T1 via the medial cord of the brachial plexus.
Motor Differentiation (Intrinsic Hand Muscles)
- Hand muscle are innervated by two nerves
- Ulnar nerve
- innervates all intrinsic hand muscles, except for a specific group of five muscles (which are innervated by median nerve)
- Median nerve
- innervated by C8 and T1 via the median nerve
- Lateral two lumbricals (Lumbricals I and II).
- Opponens pollicis (OP):
- Allows the thumb to contact the fifth finger.
- Abductor pollicis brevis (APB):
- Elevates the thumb about the metacarpophalangeal joint (MCP) to 90 degrees relative to the plane of the palm.
- Flexor pollicis brevis (FPB).
- These muscles will have normal power in Ulnar nerve palsy but weak in C8/T1 radiculopathies
Between DCM vs ALS
Feature | ALS (Amyotrophic Lateral Sclerosis) | CSM (Cervical Spondylotic Myelopathy) |
Cause | Progressive neurodegenerative disease of upper and lower motor neurons | Chronic, non-traumatic, progressive cervical cord compression due to degenerative spine disease |
Clinical Course | Fatal, progressive; most die within 2 years of diagnosis | Progressive; treatable; requires surgery in moderate-severe cases |
Motor Symptoms | Weakness, atrophy, fasciculations, spasticity, upper & lower motor neuron signs | Weakness, clumsiness, atrophy, hyperreflexia, spasticity; upper motor neuron signs predominate (anterior horn involvement possible) |
Bulbar/Cranial Nerve & Cognitive Involvement | Bulbar signs common: dysarthria, dysphagia, tongue atrophy/fasciculations; up to 50% may exhibit cognitive (especially executive) dysfunction or frontotemporal dementia | No bulbar or cognitive involvement |
Sensory Symptoms | Absent | Sensory changes common (paresthesia, numbness) Pure motor forms ("cervical spondylotic amyotrophy") exist and mimic ALS |
Diagnostic “Red Flags” | Bulbar/cognitive/behavioral symptoms Rapidly progressive weakness Split-hand atrophy Tongue fasciculations Absence of marked sensory or sphincter signs | Sensory level on exam Typical radiological finding Sphincter dysfunction Absence of bulbar/cognitive features Improvement or stabilization with surgery |
Sphincter Dysfunction | Rare in ALS; points against diagnosis if present | Early or significant sphincter dysfunction points toward CSM |
EMG/Neurophysiology | Shows widespread denervation (fibrillations, sharp waves), both upper and lower motor neuron features, including unaffected limbs; lower motor neuron degeneration in areas without clinical deficit | Abnormalities confined to compressed spinal segments; EMG and nerve conduction can help exclude ALS and peripheral neuropathies. Special EMG differences: e.g., ulnar/median CMAP ratios, repetitive stimulation more abnormal in ALS; "split hand" and MUNIX tests helpful |
Imaging | MRI is normal or shows only muscle atrophy; does not show cord compression | MRI: confirms cord compression (criteria needed for diagnosis); important as imaging alone may not rule out ALS—must correlate with symptoms |
Prognosis | Invariably progressive; no disease-modifying cure available | Potential for stabilization or improvement post-surgery; surgical treatment indicated as disease progresses |
Treatment | Supportive, multidisciplinary; manage symptoms, maintain nutrition and respiration; surgery not beneficial (may even cause diagnostic delay or iatrogenic intervention) | Physical therapy, immobilization, anti-inflammatories, removal of high-impact activities, followed by surgery (anterior or posterior approach, depending on case) for moderate-severe or progressive disease |
Misdiagnosis/Overlap Issues | Very high risk of being misdiagnosed as CSM (CSM is the most common neurologist-made misdiagnosis in ALS); up to 14% undergoes unnecessary surgery; imaging and clinical "red flags" are critical for correct differentiation | CSM can have pure motor forms that closely resemble ALS ("CSA"); when ALS and CSM co-exist, surgical outcomes are poor, and improvement is rare; careful clinical and neurophysiological assessment required |
Diabetic Patient with Myelopathy
- Hyperreflexia and pathologic reflexes are not reliable
- Pay attention to radiologic studies
- Carefully evaluate the patient's symptoms
- Assess gait disturbance or manual dexterity for diagnosis of myelopathy
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