Iatrogenic Occipital Neuralgia After Scalp Epidermoid Cyst Excision: A Rare Case Report

Abstract

Background:

Occipital neuralgia is a relatively frequent but often intractable headache disorder typically arising from trauma or nerve entrapment. While commonly associated with spontaneous or degenerative causes, iatrogenic occipital neuralgia following scalp surgery is rare and underreported in the literature. Reporting this case highlights the diagnostic challenge and surgical relevance of an underrecognized etiology.

Case presentation:

A healthy 31-year-old female developed stabbing occipital pain radiating to the forehead after incomplete excision of a left occipital scalp tumor under local anesthesia. Examination revealed paroxysmal pain without sensory loss in the distribution of the greater occipital nerve, associated with dysesthesia and tenderness. A soft residual mass remained near the surgical site. Diagnostic occipital nerve block with lidocaine resulted in temporary pain relief, confirming occipital neuralgia. Surgical excision and neurolysis of the greater occipital nerve were performed. The patient experienced complete resolution of pain, with minimal residual numbness postoperatively.

Conclusions:

This case illustrates a rare instance of iatrogenic occipital neuralgia following scalp surgery. It underscores the importance of evaluating prior surgical history in patients with new-onset occipital pain and highlights the utility of occipital nerve block as a diagnostic tool. Greater occipital nerve injury or local inflammatory sequelae may result in persistent neuropathic pain, which can be effectively addressed through decompression or neurolysis. Preoperative knowledge of neuroanatomy and meticulous surgical technique are vital to preventing such complications.

Introduction

Occipital neuralgia is a painful headache disorder characterized by lancinating or throbbing pain in the distribution area of the greater occipital nerves, lesser occipital nerves, and third occipital nerves. The pain typically originates from the neck or skull base and radiates toward various regions, such as the fronto-orbital regions, ear, temple, upper neck, and lower occipital scalp.^1,2 Sometimes such pain can radiate to the forehead and eye, resembling the distribution of the ophthalmic branch of the trigeminal nerve.^3,4 The diagnosis of occipital neuralgia is based on specific criteria outlined in the International Classification of Headache Disorders Third Edition (ICHD-3; Table 1), which include shooting, stabbing, or sharp pain quality, and tenderness over the affected nerves. However, the definitive diagnosis also relies on transient pain relief following a local occipital anesthetic block.^1,5,6

Table 1.

Diagnostic Criteria for Occipital Neuralgia from ICHD-3 Diagnosis.

A. Unilateral or bilateral pain in the distribution(s) of the greater, lesser and/or third occipital nerves and fulfilling criteria B-D

B. Pain has at least two of the following three characteristics:

1. recurring in paroxysmal attacks lasting from a few seconds to minutes

2. severe in intensity

3. shooting, stabbing or sharp in quality

C. Pain is associated with both of the following:

1. dysesthesia and/or allodynia apparent during innocuous stimulation of the scalp and/or hair

2. either or both of the following:

a. tenderness over the affected nerve branches

b. trigger points at the emergence of the greater occipital nerve or in the distribution of C2

D. Pain is eased temporarily by local anesthetic block of the affected nerve(s)

E. Not better accounted for by another ICHD-3 diagnosis.

The exact prevalence remains uncertain due to potential misdiagnosis, as occipital pain is often labeled as occipital neuralgia without proper evaluation. Injuries to the C2–C3 nerve roots through various mechanisms, such as entrapment, trauma, inflammation, or whiplash, can contribute to its development. ⁷ Common treatment modalities include medications, physical therapy, nerve blocks, and botulinum toxin injections. However, these approaches may have limitations in terms of efficacy and tolerability.^8,9 For patients with refractory occipital neuralgia, surgical interventions such as nerve decompression surgery, radiofrequency ablation, and occipital nerve stimulation may be considered.^10,11 Here, we present a patient who developed iatrogenic occipital neuralgia caused by surgical excision of scalp epidermoid cyst. This complication is extremely uncommon and has rarely been reported in the literature. ¹²

Case Presentation

A 31-year-old female patient present with severe left occipital region pain radiating to the forehead for 2 weeks. She is healthy without past medical history. Two weeks prior, she underwent surgery at a regional hospital for removal of a scalp tumor in the left occipital region. During the procedure, for unknown reasons, the tumor was not completely excised. Postoperatively, the patient began experiencing pain in the left occipital region that gradually extended to the forehead. The pain is described as stabbing and tingling, with no identifiable triggering factors or temporal pattern of occurrence. Consequently, the patient come for further treatment at our hospital due to progressive occipital pain. On examination, the symptoms manifest as unilateral pain along the greater occipital nerve distribution with radiation to the ophthalmic nerve (CNV1) area, and the visual analog scale score (VAS) is 5/10. These symptoms recurr in paroxysmal attacks of severe intensity, characterized by a sharp and stabbing quality, and last all day, corresponding to typical unilateral occipital neuralgia. Additionally, there is associated dysesthesia apparent during innocuous stimulation of the scalp, along with tenderness over the greater occipital nerve innervation region. There are no other abnormal findings on neurological examination. Physical examination reveal that the surgical wound had healed well without redness, swelling, or signs of infection. At the site of the previous surgery, approximately 2.5 cm lateral to the inion, a soft movable mass measuring approximately 3 × 2 cm remaining, with mild tenderness (Figure 1). Illustration of left occipital scalp epidermoid cyst and relative location to sensory distribution patterns of the greater occipital nerve and lesser occipital nerve). After injection of Lidocaine (3 mL, 2%) around the greater occipital nerve for nerve block, the occipital pain is relieved. This confirms the diagnosis of occipital neuralgia. Due to the worsening of occipital neuralgia, we arrange tumor excision surgery with attempted decompression with neurolysis of the greater occipital nerve. After surgery, the patient recovers well, and the occipital pain disappear completely with only residual numbness over the greater occipital nerve region. The final pathological diagnosis is a scalp epidermoid cyst.

Figure 1.

Illustration of left occipital scalp epidermoid cyst and relative location to sensory distribution patterns of the greater occipital nerve and lesser occipital nerve.

Discussion

Occipital neuralgia is a symptom resulting from neural impulses originating from the greater occipital nerves, lesser occipital nerves, and third occipital nerves. The greater occipital nerve is often implicated as the primary source of occipital neuralgia, whether from nontraumatic or traumatic origins.^1,7 A structured differential diagnosis was essential to exclude other causes of post-craniotomy head and neck pain. Post-craniotomy pain syndrome, cervicogenic headache, and tension-type headache were considered but excluded based on clinical features, examination, and imaging. ¹³ The patient’s pain was localized to the greater occipital nerve distribution, reproducible with palpation, and abolished by nerve block. The absence of muscular trigger points and cervical joint pathology further reduced the likelihood of myofascial or cervicogenic origins. Diagnostic occipital nerve blocks produced transient but marked pain relief, serving both to confirm the diagnosis and to predict the likelihood of surgical benefit. This approach is consistent with current evidence that supports nerve decompression or neurolysis in selected patients with iatrogenic occipital nerve injury who demonstrate a positive diagnostic block and fail conservative therapy. ¹⁴

Examining the patient’s previous medical records, it is worth noting that there were no symptoms of occipital neuralgia before the first surgery. We speculate that the epidermoid cyst itself did not cause nerve compression. The absence of preoperative symptoms and the temporal onset of pain postoperatively strongly suggest an intraoperative or postoperative insult to the greater occipital nerve as the underlying etiology. Several pathophysiological mechanisms may explain iatrogenic occipital neuralgia in this context, including direct nerve transection, entrapment within postoperative scar tissue, and local inflammatory reactions. The occipital neuralgia that developed after the first surgery may have been due to injury to the greater occipital nerve during the surgical procedure with inflammation and adhesions in the tissues surrounding the greater occipital nerve postoperatively. Surgical exploration confirmed perineural adhesions, and neurolysis resulted in substantial symptom resolution with minimal residual numbness. Pain relief was sustained at both 3 and 6 month follow-up, indicating durable benefit. The presence of local inflammation is particularly associated with ruptured epidermal cysts. ¹⁵ This can also explain why the patient experienced significant improvement in occipital neuralgia after the second surgery, with only slight residual numbness over the left occipital scalp. In reviewing the literature, only few reports have mentioned occipital neuralgia resulting from injury to the occipital nerves after craniotomy.^12,16 The iatrogenic occipital neuralgia was less reported and should be considered in the differential diagnosis of occipital neuralgia. This case highlights the rare occurrence of iatrogenic occipital neuralgia after a minor scalp procedure, a complication seldom reported in the literature. Limitations include a single reported case, selection and reporting bias cannot be excluded. Potential confounding headache disorders may also have influenced the clinical picture, and may not fully exclude alternative etiologies.

Conclusions

In conclusion, we reported a rare cause of occipital neuralgia and suggest that clinicians consider previous scalp surgery in the differential diagnosis of patients with occipital neuralgia. This case underscores the importance of thorough preoperative neuroanatomical identification and meticulous intraoperative nerve separation technique. Incorporating these measures into routine surgical planning and follow-up may reduce preventable nerve injury and improve long-term outcomes, even in relatively straightforward procedures such as scalp tumor excision, to prevent complications in patients.