Dropped Head Syndrome

Isolated Neck Extensor Myopathy

Diagnostic Criteria (Katz et al. 1996):

1. Weakness limited to neck extensors
2. No evidence of systemic neuromuscular disease
3. EMG shows myopathic changes in neck muscles only
4. Muscle biopsy: non-inflammatory myopathy
5. Normal serum CK
6. Negative autoantibodies

Characteristics: Age over 65 typically, female predominance, gradual onset over weeks to months, may stabilize or slowly progress.

Prognosis: Generally better than secondary causes. Some spontaneous improvement reported. Conservative management effective in early/mild cases.

Systemic Neuromuscular Disease

Myasthenia Gravis:

• Check AChR antibodies (positive in 85%)
• MuSK antibodies if seronegative
• Ptosis, diplopia, limb fatigability
• Repetitive nerve stimulation shows decrement

ALS:

• Upper and lower motor neuron signs
• Fasciculations, hyperreflexia
• Tongue atrophy and fasciculations
• Progressive, average survival 3-5 years

Inflammatory Myopathy:

• Elevated CK (10-50x normal)
• Proximal limb weakness
• Characteristic rash in dermatomyositis
• Responds to steroids/immunosuppression

Muscular Dystrophy: Facioscapulohumeral dystrophy (FSHD) can present with neck weakness. Myotonic dystrophy may cause head drop. Genetic testing is helpful for diagnosis.

Post-Surgical:

• After extensive cervical laminectomy
• Multilevel foraminotomy
• Muscle detachment during exposure

Post-Radiation:

• Delayed onset (6 months to years)
• Fibrosis of paraspinal muscles
• Often progressive

Drug-Induced:

• Statin myopathy
• Steroid myopathy
• Botulinum toxin (excessive dose for dystonia)

Management: Remove offending agent if possible. Surgery often required for post-surgical and post-radiation cases.

Structural Causes:

Cervical Spondylosis:

• May cause myelopathy mimicking weakness
• Osteophytes and stenosis
• Combined decompression and fusion

Ankylosing Spondylitis:

• Chin-on-chest fracture-dislocation
• Osteoporotic vertebral collapse
• Unstable spine requires stabilization

Parkinson Disease:

• Anterocollis distinct from DHS
• Responds to L-dopa adjustment
• Botulinum toxin may help

Assessment: X-ray, CT, and MRI to assess bony and soft tissue pathology. Treatment directed at underlying cause.

Laboratory Investigations

First-Line:

Second-Line:

Electrodiagnostic Studies

EMG (Electromyography):

Nerve Conduction Studies:

• Normal in INEM
• Decremental response in MG
• Helpful to exclude neuropathy

Imaging

X-ray:

• Assess degree of kyphosis
• Measure chin-brow vertical angle (CBVA)
• Evaluate for fracture or spondylosis

MRI:

• T1-weighted: Fatty infiltration appears hyperintense
• T2-weighted: Edema in acute phase
• Key muscles: Semispinalis cervicis, capitis
• Assess for cord compression
• Evaluate cord signal (myelomalacia)

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CT:

• Bone detail for surgical planning
• Fusion assessment if prior surgery
• Fracture detection

Muscle Biopsy

Indications:

• Diagnosis uncertain after non-invasive workup
• Suspected inflammatory myopathy
• Atypical presentation

INEM Biopsy Findings:

• Fiber size variation
• Type 2 fiber atrophy
• No inflammation
• No necrosis
• Possible fatty replacement

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Technique:

• Open biopsy of paraspinal muscle
• Usually semispinalis cervicis
• Sufficient sample for histology and special stains

Indications:

• Flexible deformity
• Early presentation (less than 3-6 months)
• Mild symptoms
• High surgical risk

Components:

Physical Therapy:

• Neck extensor strengthening exercises
• Postural retraining
• Stretching of anterior structures
• Aquatic therapy

Orthoses:

• Cervical collar (soft or rigid)
• Custom orthosis for chin support
• May not halt progression but provides comfort

Medications:

• Treat underlying condition (e.g., steroids for inflammatory myopathy)
• Pyridostigmine for MG
• No specific medication for INEM

Duration: Trial of 3-6 months of conservative management. If deformity progresses or becomes fixed, surgery is indicated.

Indications:

• Failed conservative management
• Fixed deformity
• Secondary myelopathy
• Significant functional impairment

Surgical Goals:

1. Restore horizontal gaze
2. Decompress spinal cord if necessary
3. Achieve stable fusion
4. Prevent progression

Approach Selection:

Levels:

• Upper: C2 (or occiput if needed)
• Lower: Extend to T2-T4 for adequate anchor
• Upper thoracic extension prevents junctional kyphosis

Instrumentation: Lateral mass screws are placed from C3-C6, with C2 pedicle or pars screws superiorly and thoracic pedicle screws inferiorly. Consider cement augmentation in osteoporotic bone for improved fixation.

Posterior Approach:

Positioning:

• Prone on Jackson frame
• Head in Mayfield pins
• Arms tucked
• Careful head positioning to avoid increased kyphosis

Exposure:

• Midline incision C2 to upper thoracic
• Subperiosteal dissection
• Identify lateral masses and transverse processes

Instrumentation:

• Start distally and work proximally
• Correct kyphosis with rod contouring
• Compression across posterior elements
• May use temporary distraction to correct deformity

Fusion:

• Decorticate lateral masses and facets
• Local bone graft and/or allograft
• Consider BMP in selected cases

Anterior Release (if needed): Smith-Robinson approach is used for anterior release with discectomies at contracted levels. May require corpectomy for severe deformity with structural graft or cage placement.

Immobilization:

• Rigid cervical collar for 6-12 weeks
• Consider halo vest for severe cases or poor bone

Rehabilitation:

• Gradual mobilization
• Physical therapy for neck and core
• Postural education
• Dysphagia assessment and management

Follow-up:

• Clinical and radiographic at 6 weeks, 3 months, 6 months, 1 year
• Assess fusion on CT at 6-12 months
• Monitor for adjacent segment disease

Expected Outcomes: Good correction of deformity is achieved in most cases with improved horizontal gaze and stabilization of neck. Patients may have persistent weakness due to the underlying myopathy.

Posterior Cervical Fusion for Dropped Head Syndrome

Surgical Approach

Positioning:

• Prone on Jackson table or Mayfield head holder
• Position head in as much correction as safely tolerated
• Neuromonitoring (SSEP, MEP) essential
• Fluoroscopy to confirm alignment

Exposure:

• Posterior midline approach
• Subperiosteal dissection to expose lateral masses
• Identify occiput if occipitocervical fusion planned
• Extend to upper thoracic if long construct needed

Fixation Options:

• Lateral mass screws (C3-C6)
• Pedicle screws (C2, C7, thoracic)
• Occipital plate if occipitocervical fusion
• Rods contoured to restore lordosis

Surgery aims to restore horizontal gaze and stabilize the cervical spine in corrected alignment.

Advanced Surgical Techniques

Correction Techniques

Gradual Intraoperative Correction:

• Sequential rod contouring and exchange
• Cantilever correction using posterior screws
• Smith-Petersen osteotomies if needed (rarely)
• Constant neuromonitoring during correction

Staged Correction with Halo Traction:

• Halo vest or ring application
• Gradual traction over days-weeks
• Serial radiographs to monitor correction
• Posterior fusion when alignment achieved

Anterior Release if Rigid:

• Anterior discectomies at kyphotic apex
• Followed by posterior instrumented fusion
• Reserved for very rigid deformities
• Higher morbidity, rarely needed

Technical Considerations

Bone Grafting

Fusion Bed Preparation:

• Decorticate lateral masses and laminae
• Prepare facet joints for fusion

Graft Options:

• Local autograft (from decompression)
• Iliac crest autograft
• Allograft (structural or morselized)
• BMP may be used (off-label in cervical spine)

Surgical technique must balance the need for correction with the significant risks in this often elderly, comorbid patient population.

Immediate Postoperative Care

Early Postoperative Management

Wound Care:

• Check wound daily for hematoma, drainage
• Drain removal at 24-48 hours when output minimal
• Suture/staple removal at 2-3 weeks

Pain Management:

• Multimodal analgesia
• Avoid excessive opioids (respiratory depression)
• Muscle relaxants may help spasm

Mobilization:

• Sit upright day 1 if stable
• Walk with assistance day 1-2
• Physical therapy for gait and balance
• Avoid lifting greater than 2 kg for 6 weeks

Close monitoring in the immediate postoperative period is essential given the high-risk nature of this surgery.

Extended Postoperative Care

Special Considerations

Rehabilitation

Physical Therapy Goals:

• Maintain range of motion in unfused segments
• Strengthen shoulder girdle muscles
• Improve posture and balance
• Gait training if deconditioning

Occupational Therapy:

• Adaptive equipment if needed
• Energy conservation techniques
• Return to activities of daily living

Postoperative rehabilitation focuses on optimizing function while protecting the fusion construct until solid union is achieved.

Clinical Outcomes

Outcome Measures

What Surgery Achieves:

• Restores ability to look forward and see horizon
• Improves eating and swallowing (if due to chin-on-chest position)
• Enhances social interaction (eye contact)
• Reduces neck pain from chronic flexion

What Surgery Does NOT Achieve:

• Does not cure underlying neuromuscular disease
• Does not restore normal neck motion
• May not prevent progression of underlying condition
• Does not guarantee pain-free outcome

Patient expectations must be realistic - surgery improves alignment and function but does not cure the underlying condition.

Detailed Outcome Analysis

Complications and Their Impact

Long-Term Outcomes

Fusion Rates:

• Overall fusion: 75-90%
• Pseudarthrosis risk increases with: poor bone quality, long constructs, systemic disease
• May require revision with bone grafting if symptomatic nonunion

Adjacent Segment Disease:

• Occurs in 10-20% at 5 years
• Higher with longer constructs
• May require extension of fusion

Survival and Function:

• Overall prognosis determined by underlying disease
• Parkinson's patients: continued neurological decline expected
• INEM patients: better long-term function
• Quality of life generally maintained post-surgery

Prognostic Factors

Outcomes are generally favorable for symptomatic improvement, though complication rates are significant and long-term issues including adjacent segment disease should be anticipated.